LaPOD: Low cost Logic Analyzer probe for MSO5k, DHO900 and more!

[oliv3r]

After seeing a couple of great pod designs, I decided I wasn't quite happy with the designs overal.

What I wanted was to use (mini) HDMI cables, as they are cheap, super common and shielded. Also 4 channels per pod had my preference, to make them nice and small.

The design is based on a breakout board, that plugs into the scope, and offers 4 (mini) HDMI connectors. The other end consists of a POD, featuring either a LMH7322 (like the original), LMH7324 (cheaper quad channel part) or SNV65LVDS (much cheaper, less flexible) comparator. Mix-n-match is the keyword here, feel unrestricted in what pod to connect, get 4 LMH7322 based pods, or one of each. In the future, more pods may be added if it makes sense.

As for the breakout board, there's currently two models, both with 50pin IDC connectors, matching the MSO5000 series and DHO900. The mini-HDMI variant was made to offer a super small/narrow profile, which is nice for the DHO900, but either work. In the future, given we have some testers/interest, we can very easily add a 68pin IDC variant for the DS1074 series, and very likely also for the PCIe based scopes such as the DSO7k and MSO8k series.

Some words on the other great designs.
Gandalf_Sr's Budget probe set design.
https://www.eevblog.com/forum/testgear/ms05000-budget-logic-analyzer-probe-set-design/msg2938442/#msg2938442
At first, it seemed like a good idea, but I didn't like that it wasn't open source so couldn't even respin it. Secondly, I liked the idea and even was planning on doing a pod for it, but the SNV65LVDS seemed more sensible at the time.

S. Petrukhin's easy eda low cost probe
https://www.eevblog.com/forum/testgear/low-cost-logic-analyzer-probe-for-rigol-mso5000-easyeda-project/
I really liked this design, but the many small comparators I didn't quite like, nor the flat cable design. But it was the thread that inspired me (after 3 years? to finally make my own design) after the suggestion of the SNV65LVDS. It was open-source though, but easy-eda

Nikki Smith's variant
https://climbers.net/sbc/clone-pla2216-logic-probe-analyzer/
Was what really maybe got me moving, as he did the work in KiCad and used the LMH7322 and LMH7324. I really wanted to have balanced lines (lapod all traces are length-matched). But, still wrong connector I was still hung up on the HDMI bit. Also Nikki went silent after september

dren.dk's first foss unit
https://gitlab.com/dren.dk/mso5k-la-pod/tree/master
The name was actually inspired from this post https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/msg2125477/#msg2125477 LA pod. But 8 pins in a pod was not my liking, and flat cables.

thmjpr's USB-C variant
https://gitlab.com/thmjpr/stm32f03_la_monitor
I do like the idea of using USB-C cables, but USB-C cables are a huge pain. are all wires routed, does it have an E chip, will that be in our way. Should we do USB-PD on the breakout board? Also, reversability is cool, but not ideal for the breakout.

Others I have missed? Regardless. Here's my variant

All schematics and stuffs come from the pipeline when released https://gitlab.com/riglol/lapod/-/releases, and I've attached a whole bunch of some WIP stuff here https://www.eevblog.com/forum/testgear/another-low-cost-la-probe-for-rigol-mso5000-by-oliv3r/msg5311123/#msg5311123

Note, that I haven't ordered any PCB's yet, and nothing is tested. It just looks really sexy in the renderings :p


EDIT 2024-02-03: Changed the starting post as we are now our own thread. Find below the remainder of the starting post
(left-over of the original first post)
I am too working on a respin of this

mostly, because I wanted to use HDMI cables and 4 channels per pod. Here's my WIP screenshot; but it's far from finished. The pinout of the connector is crazy, causing all sorts of weirdness to be needed in routing bits, and to have at least the easiest routing, the connectors will end up having a weird order, J2, J4, J1, J3, which will translate to port1, will have pins 5 - 8, port2, 13 - 16, port1 1 - 4, port3, 9 - 12, which I admit is a bit odd, but keeps routing sane, or the size down, whichever you prefer.

I'll route the other bits next (which is just power and gnd) and then route the pods.

For those curious, I'll also attach a screenshot of the HDMI pinout to shout and shame

[ebastler]

The pinout of the connector is crazy, causing all sorts of weirdness to be needed in routing bits, and to have at least the easiest routing, the connectors will end up having a weird order, J2, J4, J1, J3, which will translate to port1, will have pins 5 - 8, port2, 13 - 16, port1 1 - 4, port3, 9 - 12, which I admit is a bit odd, but keeps routing sane, or the size down, whichever you prefer.
[...]
For those curious, I'll also attach a screenshot of the HDMI pinout to shout and shame

Not sure I understand how the pinout of the HDMI connector could drive the need to swap the sequence of the pods. I would expect the HDMI pinout to potentially force an awkward order of the four channels within each pod group, but the pod sequence to follow the order on the scope's connector?

[UK]

I wanted to use HDMI cables and 4 channels per pod.

Why HDMI exactly? Why not RJ-45 LAN cable? Moreover, Cat-7 / 8 cables have superior shielding for each pair, the connector with fixation also may be a very handy feature when a lot of stuff is going on on your table. Also, RJ-45 also has more robust contacts than an HDMI.

[oliv3r]

I wanted to use HDMI cables and 4 channels per pod.

Why HDMI exactly? Why not RJ-45 LAN cable? Moreover, Cat-7 / 8 cables have superior shielding for each pair, the connector with fixation also may be a very handy feature when a lot of stuff is going on on your table. Also, RJ-45 also has more robust contacts than an HDMI.

All true, but RJ45 doesn't have enough pins. You can do 4 channels, but then have no power or anything. If you do all power pins, you end up with just 2 channels, which is usable, but leaves a lot to be desired ...

HDMI cables are cheap and easy to get, and give you differential pairs too. The 5V pin is gonna be a challange, as cheap cables will not allow much current to go through, but must let 50ma go through at the very least to pass certification.

The pinout of the connector is crazy, causing all sorts of weirdness to be needed in routing bits, and to have at least the easiest routing, the connectors will end up having a weird order, J2, J4, J1, J3, which will translate to port1, will have pins 5 - 8, port2, 13 - 16, port1 1 - 4, port3, 9 - 12, which I admit is a bit odd, but keeps routing sane, or the size down, whichever you prefer.
[...]
For those curious, I'll also attach a screenshot of the HDMI pinout to shout and shame

Not sure I understand how the pinout of the HDMI connector could drive the need to swap the sequence of the pods. I would expect the HDMI pinout to potentially force an awkward order of the four channels within each pod group, but the pod sequence to follow the order on the scope's connector?

because the connector's pin-order isn't in sequence So i took the effort to make sure that the 4 pins within the HDMI connector are in order, so that took a lot of swapping. But swapping all pins for all connectors just takes way to much PCB space to keep the connector within reasonable size. Also, I wanted to keep the inner layers for power and ground, if I'd put signals on the inner layers, i could have swapped about a little bit more ...

[UK]

Okay, now it makes sense. But why not a Mini DisplayPort, it's smaller but has all the same.
Or even a full-size DisplayPort, since it has a fixing feature.

[oliv3r]

Those thoughts crossed my mind too, but mini-hdmi connectors are much harder to source; but what's worse, mini-hdmi cables are much harder to source

also, as you can see, from a size point of view, it doesn't matter much.

same goes for displayport. HDMI you can get for a couple of € from action or poundshop or what not. They are 'ubiquitous'. Even when the HDMI consortium is evil

[UK]

By the way, how is it going with pin swapping to make all channels in order?

[oliv3r]

for now 'not happening' :p

so each pod will have properly ordered pins, just the main breakout won't (for now, but re-doing that one is simple now, only had redone it 5 times, due to size, manufacturing, differential matching mistakes); but if you look at the pinout you'll see why, they are just to spread out, but maybe i'll give it one more go later (or someone else :p) I'll post my WIP kicad files soon so that others can tinker with it.

The problem, is that one channel will end up going from completely left, to completely right, meaning each trace will need to be this long, requiring a lot of space to snake around, thus the PCB will become bigger (sticking out the front more), which i'd rather avoid ...

[oliv3r]

The first pod, based on the LM7324 is ready, and boy was it a party :p

I'll do an LM7322 next, followed by some cheaper simpler chips as found in these threads.

The current pod PCB size is 4.5 cm X 3.0 cm using all 2012 (metric) hand solderable bits. Using 0402 (metric) would be much more fun :p but that's an exercise left for actually producing these units with automated pick-and-place solutions.

[UK]

It looks sleek, but it would be great to add a small led on it.
When you have a mess on the table, especially when you use all four pods it will be nice to have some illumination as to what pods are connected to MSO. 

[oliv3r]

It looks sleek, but it would be great to add a small led on it.
When you have a mess on the table, especially when you use all four pods it will be nice to have some illumination as to what pods are connected to MSO. 

Fair enough, I did add leds to the pod, to indicate which 'type' is connected (e.g. the LM7324 one will be blue, the LM7322 will be red + green). Having matching leds on the pod would be a nice idea, I'm a little worried with regards to power consumption.

[oliv3r]

So the LM3222 was a lot easier to do, but (due to double the chips) is slightly larger. I've added an LED, though not sure how to make it visible later. I guess heatshrink instead of a case is certainly an option

Once I've done all the pods, I'll size them up to be all the same size with the mounting holes in the same location, and the led as well

Here as before, big 2012 (metric) caps and resistors except for the differential resistors, everything should be length matched. Impedance matching is probably not the the case ...

[oliv3r]

Finished the sn65lvds variant, which was the easiest and most pleasurable to route; also because it had the most space available It is basically Nikki's design, but with trace length matching, and using 4 channel pods of course.

Gonna use this as the size of the PCB and cleanup the previous editions next, making sure the LED is on the same spot etc ...

[oliv3r]

Read back this thread, and saw discussion about the need, or lack thereof, matching the traces for delay's. I know the scope doesn't match traces either, if we look at the X-Ray ...

I never put the following pic on https://gitlab.com/riglol/rigolee/firmware/-/wikis/MSO5000%20teardown (cropped due to size restriction of the forum). I'll see if I can trace it out in kicad to determine an estimated trace length ...

but again, rigol doens't care either

Rigol does care, I just found a pretty good shot which shows the serpentines clearly (bastardized to jpeg cause of forum)

[ebastler]

I'm sure I have overlooked it somewhere in the thread, but could you please (re-)state the specifications of the LM7322 and LM7324 versions? Do they have configurable thresholds (in which range)? What's the range of input voltages and what is the speed? Thanks!

[oliv3r]

I'm sure I have overlooked it somewhere in the thread, but could you please (re-)state the specifications of the LM7322 and LM7324 versions? Do they have configurable thresholds (in which range)? What's the range of input voltages and what is the speed? Thanks!

I have no idea, I just took other people's design , or rather, the LM7322 is the same chip used in the offical probe, which was reverse engineered. The LM7324 is a quad driver, hoped to be cheaper ...

[ebastler]

Could you point to those designs you used as a starting point? I had come across a thread once which aimed to do a full-spec replica of the Rigol probe, but it is not this thread here, right?

Also, could you restate the comparator part numbers please? Are they LMH732x?

[UK]

Hey folks, just finished a shell for oliv3r's pods in Rigol's triangle style. The shell should print vertically as two halves without any supports. And as you can see it has a small oblong cutout and a light channel under it to make the LED shine in the center. It also has a flat lowering in the bottom for the label with channel numbers, which should prevent its easy pealing.

Hope you like it!

When oliv3r finalizes all PCB dimensions I'll do final refinements and upload STLs.

[ebastler]

Nice! Looks very "Darth Vader" to me, matching the MSO5000. 

[oliv3r]

By the way, how is it going with pin swapping to make all channels in order?

for now 'not happening' :p

So it happened. I took some measurements and realized my current design was super small. Which is great, and would have fit, but I was under the impression, the traces aren't length matched within the unit, might as well just fix the ordering with different length traces. But turns out, it is probably length matched within the scope (lets just hope they didn't take the mismatch of the bods into account).

Anyway, with the new measurements in hand, looking at the probe design, I figured, I'm so zoomed in, I can easly spare 3 - 5 mm. Also, I've learned how to do _proper_ differential track length matching in kicad (did it manually per track before, which was of course not good), figuring that would save me quite some space too. It did, but also using the 4 layers gave me plenty of beef to work with. So without further ado, correctly ordered breakout.

Also attached is a screenshot of what it looks like on the various layers.

Next steps, adding kicad automation to generate all the outputs from the pipeline, addinga pipeline, putting it all in git and pushing it to gitlab.

Also, some silkscreen fixups, attributions etc are deff. also in order. I really should fork this to its own topic too ...

[ebastler]

Congratulations on solving that puzzle -- nice job!

EDIT: Looking again at the layout, I think there is a bit more puzzling to be done. The orange traces in general don't look length-matched to me; the traces for IN9 in particular are much shorter than any of the other pairs?

On the silkscreen, and also when you create a new thread about this, I would not call it an "MSO5000" LA board. The new DHO900 series (low-cost 12 bit scopes) uses the exact same pinout for the LA probes, and will certainy get a lot of attention. So be sure to let those users know about your probe too! 

If you could take a moment to address my earlier question? Thanks!

Could you point to those designs you used as a starting point? I had come across a thread once which aimed to do a full-spec replica of the Rigol probe, but it is not this thread here, right?

Also, could you restate the comparator part numbers please? Are they LMH732x?

[tooki]

Okay, now it makes sense. But why not a Mini DisplayPort, it's smaller but has all the same.
Or even a full-size DisplayPort, since it has a fixing feature.

The full-size DisplayPort is possibly the least-reliable connector I have ever encountered. Because of how the plugs are implemented (a PCB with the contacts soldered to each side, and the wires from the cable to that PCB, but not overmolded because of the latching release button), they are extremely susceptible to damage from bending. Literally every DP cable I’ve encountered in the wild has had to be replaced at least once. Mini-DP is a far more robust connector.

Those thoughts crossed my mind too, but mini-hdmi connectors are much harder to source; but what's worse, mini-hdmi cables are much harder to source

also, as you can see, from a size point of view, it doesn't matter much.

same goes for displayport. HDMI you can get for a couple of € from action or poundshop or what not. They are 'ubiquitous'. Even when the HDMI consortium is evil

They didn’t say mini-HDMI, they said mini-DisplayPort. They are available.

The biggest risk with using popular connectors like HDMI for some other signal is what happens if someone connects a cable with an actual HDMI signal to it. (Not entirely crazy, given how modern scopes have HDMI outputs.) Will it damage your device? Will it damage the HDMI device?

In this regard, a more obscure connector — or one which was not designed specifically for a common consumer use — is a better choice.

[ebastler]

The biggest risk with using popular connectors like HDMI for some other signal is what happens if someone connects a cable with an actual HDMI signal to it. (Not entirely crazy, given how modern scopes have HDMI outputs.) Will it damage your device? Will it damage the HDMI device?

At least oliv3r is in good company there: Siglent use an "HDMI" connector for their proprietary S-BUS interface to an external logic analyzer module. It's right on the front panel of various entry-level scopes. 

Looking at the renderings above again, I have a different concern about the full-size HDMI connectors though: @oliv3r, is there enough room for the HDMI plugs' plastic bodies? Looks like the jacks are spaced very closely together.

[UK]

And I think so too, there isn't enough space between the ports... especially for standard cheap cables.

As a possible option to solve the problem with the PCB dimensions is to swap the current HDMI sockets to the upright/vertical version.

[ebastler]

Could you point to those designs you used as a starting point? I had come across a thread once which aimed to do a full-spec replica of the Rigol probe, but it is not this thread here, right?

Also, could you restate the comparator part numbers please? Are they LMH732x?

Answering my own question, since oliv3r seems to drop in only sporadically:

The thread on analyzing and replicating the original MSO5000 logic probe (PLA2216) is here: https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/. And the comparators are indeed the LMH7322 (dual comparator) and LMH7324 (quad). Both are available from Mouser etc., and both are on the expensive side.

Regarding the form factor of a logic probe, I am not sure whether I prefer Rigol's approach (all 16 channels routed to a large external pod) or oliv3r's (4 pods with 4 channels each). Rigol's design clearly limits flexibility, requiring all 16 probed channels to be relatively close to each other on the PCB under test; and it has the bulky, broad flat cable connection. But four HDMI cables can get a bit messy too...

And it's worth mentioning that Rigol tells you not to hot-plug the logic probe connector! Having those individual HDMI-style jacks on the front may just be too tempting?

The other thread has one version with 4x4 channels, but using USB-C connectors -- debatable, since inserting the plugs the wrong way round will swap the channels, it seems.  It also includes a design for 2 pods with 8 channels each, connected via narrower flat cables. That one might actually hit the sweet spot for me -- but I am not sure whether it was fully polished and tested.

[oliv3r]

Hey folks, just finished a shell for oliv3r's pods in Rigol's triangle style. The shell should print vertically as two halves without any supports. And as you can see it has a small oblong cutout and a light channel under it to make the LED shine in the center. It also has a flat lowering in the bottom for the label with channel numbers, which should prevent its easy pealing.

Hope you like it!

When oliv3r finalizes all PCB dimensions I'll do final refinements and upload STLs.

That looks friggin sexy as heck

can you also do one for the breakout board? Here's the dimensions I have for now, but since the boards aren't proven to be working (haven't built them yet) can't say that it won't change (but I have to doubt that ...)

The slot in the middle for the led looks ubernice should be doable with a light-guide, hotglue usually works great :p However, I'm not sure I can get the LED in the middle like that, see the dimensions I have for now. I could wiggle in the LED between the resistors and the connector, but probably will need to enbiggen the PCB a little ...

The breakout doesn't have mounting holes, shouldn't be an issue with proper dimensions I suppose, but there isnt' much room to add them either ...

[ebastler]

A 17 mm pitch is definitely not going to work for the HDMI sockets. The slimmest HDMI plug I can find in my home is 20 mm wide.

I find it a bit frustrating that you post something and disappear again for days right away, not responding to any questions or concerns. Yes, you can use this forum as a one-way broadcastig channel, but you are losing the opportunity to improve your design, and may lose your audience. Personally I would rather roll my own PCB design, because it seems increasingly unlikely that you will listen to suggestions.

Edit: Strikethrough. 

[oliv3r]

Congratulations on solving that puzzle -- nice job!

EDIT: Looking again at the layout, I think there is a bit more puzzling to be done. The orange traces in general don't look length-matched to me; the traces for IN9 in particular are much shorter than any of the other pairs?

You are right!! The orange ones are the longest traces, so figured those would be easiest and could be done last, but forgot here's the traces lengthen :p

On the silkscreen, and also when you create a new thread about this, I would not call it an "MSO5000" LA board. The new DHO900 series (low-cost 12 bit scopes) uses the exact same pinout for the LA probes, and will certainy get a lot of attention. So be sure to let those users know about your probe too! 

I called it LA14 before, just cause ... but please, come up with some cool names

LM7322 and LM7324 are the two used LM parts, the other one is the sn65lvds. My signature has all the rigol related links, but I think this thread included most info? I don't remember which one has the best data. ...

If you could take a moment to address my earlier question? Thanks!

Could you point to those designs you used as a starting point? I had come across a thread once which aimed to do a full-spec replica of the Rigol probe, but it is not this thread here, right?

Also, could you restate the comparator part numbers please? Are they LMH732x?

[ebastler]

I called it LA14 before, just cause ... but please, come up with some cool names

The Rigol logic analyser probe it replaces is the PLA2216. "PLA2216 replacement" would be clear but not cool... Maybe "PLA2216 plus" or such, because it is actually better than the original (from a handling perspective)?

LM7322 and LM7324 are the two used LM parts

No, those are not the correct numbers, that's why I asked. LM7322 is a plain old op-amp; LM7324 does not exist at all. It's LMH732x. Should be fixed on the silkscreen of the probe PCBs!

I think this thread included most info? I don't remember which one has the best data.

The present thread is the "low cost probe" one, which originally focused on the cheaper CMOS/TTL-level pods only. As mentioned a few posts above, I have found the other relevant thread in the meantime. It looks into using the original LMH732x comparators, and has a few schematics and layout suggestions for those: https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/.

[UK]

can you also do one for the breakout board?

Sure, but it will definitely take some time with my current job.

That looks friggin sexy as heck

I'm glad you like it too. I've dived a bit deeper into the MSO5000 look and made several touches... now it definitely looks in its authentic style.

[oliv3r]

Okay, now it makes sense. But why not a Mini DisplayPort, it's smaller but has all the same.
Or even a full-size DisplayPort, since it has a fixing feature.

The full-size DisplayPort is possibly the least-reliable connector I have ever encountered. Because of how the plugs are implemented (a PCB with the contacts soldered to each side, and the wires from the cable to that PCB, but not overmolded because of the latching release button), they are extremely susceptible to damage from bending. Literally every DP cable I’ve encountered in the wild has had to be replaced at least once. Mini-DP is a far more robust connector.

Those thoughts crossed my mind too, but mini-hdmi connectors are much harder to source; but what's worse, mini-hdmi cables are much harder to source

also, as you can see, from a size point of view, it doesn't matter much.

same goes for displayport. HDMI you can get for a couple of € from action or poundshop or what not. They are 'ubiquitous'. Even when the HDMI consortium is evil

They didn’t say mini-HDMI, they said mini-DisplayPort. They are available.

The biggest risk with using popular connectors like HDMI for some other signal is what happens if someone connects a cable with an actual HDMI signal to it. (Not entirely crazy, given how modern scopes have HDMI outputs.) Will it damage your device? Will it damage the HDMI device?

In this regard, a more obscure connector — or one which was not designed specifically for a common consumer use — is a better choice.

Sure, but this is a built for experts isn't it? I'm not gonna run production and sell millions of them to unsuspecting users :p

So if you connect your PC or laptop to your scope, the laptop's HDMI port will probably be damaged, as it's outputting power on the I2C pins at the least. Don't think the scope will care much, as all those extra used pins, are either to drive a led on the adapter, or to feed power from the adapter.

Sure, people do dumb things, but again, this isn't a consumer dumb device, and while I agree, safety first, and using a common consumer connector is a dumb idea for a commercial product, this isn't that But getting consumer HDMI cables, is easy and cheap, and they are differential pairs to boot. I just got 60cm HDMI cables for 25cents each (the shop was closing down, but still). I think even normal HDMI cables can be had for 2€ nowadays. But yes, the resistance of the voltage carrying wires will have an impact ...

[oliv3r]

The biggest risk with using popular connectors like HDMI for some other signal is what happens if someone connects a cable with an actual HDMI signal to it. (Not entirely crazy, given how modern scopes have HDMI outputs.) Will it damage your device? Will it damage the HDMI device?

At least oliv3r is in good company there: Siglent use an "HDMI" connector for their proprietary S-BUS interface to an external logic analyzer module. It's right on the front panel of various entry-level scopes. 

Looking at the renderings above again, I have a different concern about the full-size HDMI connectors though: @oliv3r, is there enough room for the HDMI plugs' plastic bodies? Looks like the jacks are spaced very closely together.

crap! I Didn't even think about that one ... i'll measure my cables and adjust accordingly. Only bit that's frustrating, is that'll probably mean I have to do my differential lines, again, and the longest one will probably be ending up even longer :S

Oh well!!

Could you point to those designs you used as a starting point? I had come across a thread once which aimed to do a full-spec replica of the Rigol probe, but it is not this thread here, right?

Also, could you restate the comparator part numbers please? Are they LMH732x?

Answering my own question, since oliv3r seems to drop in only sporadically:

true, but often threads are silent for days , and ... life happens.

The thread on analyzing and replicating the original MSO5000 logic probe (PLA2216) is here: https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/. And the comparators are indeed the LMH7322 (dual comparator) and LMH7324 (quad). Both are available from Mouser etc., and both are on the expensive side.

that's the one! the third pod is the one from this Nikki Smith's remix, he called it 'v3.1' or something.

Regarding the form factor of a logic probe, I am not sure whether I prefer Rigol's approach (all 16 channels routed to a large external pod) or oliv3r's (4 pods with 4 channels each). Rigol's design clearly limits flexibility, requiring all 16 probed channels to be relatively close to each other on the PCB under test; and it has the bulky, broad flat cable connection. But four HDMI cables can get a bit messy too...

Yeah, but cables end up always being messy, 8 cables is still too much for most of my tasks and still a big-ish cable. Also, those flat cables aren't differential cables, which is why I dislike them. 4 was the sweetspot for me, not just because hdmi has exactly 4 differential channels, but also because 4 is what you'd use for i2c + irq, or SPI + irq etc. And it does scale to use both :p one can always even do a pod with dual hdmi sockets :p

And it's worth mentioning that Rigol tells you not to hot-plug the logic probe connector! Having those individual HDMI-style jacks on the front may just be too tempting?

The other thread has one version with 4x4 channels, but using USB-C connectors -- debatable, since inserting the plugs the wrong way round will swap the channels, it seems.  It also includes a design for 2 pods with 8 channels each, connected via narrower flat cables. That one might actually hit the sweet spot for me -- but I am not sure whether it was fully polished and tested.

I think this thread, and nikki's v3 are then just what you are after. I didn't like the USB-C for the same reason, reversability AND the actual problem of more easily plugging something incorrect in. HDMI just felt 'less likely'. Initially I really wanted to do mini or micro hdmi even, and with the rasp-pi they seem slightly easier to source now ...

[ebastler]

@oliv3r, is there enough room for the HDMI plugs' plastic bodies? Looks like the jacks are spaced very closely together.

crap! I Didn't even think about that one ... i'll measure my cables and adjust accordingly. Only bit that's frustrating, is that'll probably mean I have to do my differential lines, again, and the longest one will probably be ending up even longer :S

Making the PCB wider might also run into collisions with the connector on its left -- even more so on the DHO900, which has a USB jack quite close to the logic analyzer port. Maybe look into mini-HDMI or mini-DVI again?

8 cables is still too much for most of my tasks and still a big-ish cable. Also, those flat cables aren't differential cables, which is why I dislike them. 4 was the sweetspot for me, not just because hdmi has exactly 4 differential channels, but also because 4 is what you'd use for i2c + irq, or SPI + irq etc.

Agree that 8 signals plus 8 GND wires is a lot already. I am not sure why all the individual GNDs would be needed though. My preference for an 8-signal pod would be a 2*5 pin connector (8 signals, 2 GND). That also works well with an IDC connector and colored ribbon cable, with the colors nicely matching the channel numbers.

I think [...] nikki's v3 are then just what you are after.

Nikki Smith did an updated version of the low-cost (TTL/CMOS) probe only, right -- or did I overlook something? I definitely want a probe with the large voltage range and configurable threshold provided by the LMH7324, since one of my use cases is work on vintage (tube) computers with 20V logic levels.

The design by @dren.dk is the configuration I personally like best, https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/msg2316423/#msg2316423. It needs some work though: Some signal polarities are flipped due to early mis-information about the 50 pin connector's pinout, and he did not bother with length matching of the traces.

But I am in no rush -- will wait how your design pans out, and probably borrow (and use in duplicate) your very nice LMH7324 pod layout. 

[UK]

Making the PCB wider might also run into collisions with the connector on its left -- even more so on the DHO900, which has a USB jack quite close to the logic analyzer port. Maybe look into mini-HDMI or mini-DVI again?

Why not just use vertical ones?!
Previously, I also suggested mini-HDMI and mini-DP, but after looking at the range of cables available I agreed that the ordinary HDMI is the best solution... since slim connectors, flat or soft versions of cables are not even available for mini-HDMI / DP / DVI ...unless you're a fan of cables that look like a garden hose on your table 

... that'll probably mean I have to do my differential lines, again, and the longest one will probably be ending up even longer :S

If you going to redo all differential lines again )) pls look closely at the upright HDMI sockets I've already mentioned before. Then you won't have to make a board that looks like a palm tree. And all four HDMI sockets can fit on a pcb in the width of a 50-pin header.

[ebastler]

Making the PCB wider might also run into collisions with the connector on its left -- even more so on the DHO900, which has a USB jack quite close to the logic analyzer port. Maybe look into mini-HDMI or mini-DVI again?

Why not just use vertical ones?!

They are certainly worth a try in the layout! But it seems to me that you will have to add more depth to the PCB: The connectors themselves are longer than the standard horizontal ones, and on the MSO5000 you might also need to give them extra clearance so they don't collide with the protruding scope housing above the connector.

If that PCB becomes to deep, and then has four full-size HDMI plugs and cables dangling from it, I would be worried about mechanical strain -- and about bumping into when you want to use the touch screen. Also because the assembly would come closer to the touch screen since it is taller. And it might just look a bit awkward, with the HDMI connectors sitting much higher than the row of BNC jacks and USB.

Having written the above -- maybe the vertical HDMI connectors should sit below the PCB? It might still look awkward, but you avoid the collision with the scope housing, and the plugs and cables would be further away from the touch screen.

[oliv3r]

@oliv3r, is there enough room for the HDMI plugs' plastic bodies? Looks like the jacks are spaced very closely together.

crap! I Didn't even think about that one ... i'll measure my cables and adjust accordingly. Only bit that's frustrating, is that'll probably mean I have to do my differential lines, again, and the longest one will probably be ending up even longer :S

Making the PCB wider might also run into collisions with the connector on its left -- even more so on the DHO900, which has a USB jack quite close to the logic analyzer port. Maybe look into mini-HDMI or mini-DVI again?

Hmm, I'll check the sizes again, my el-cheapo cables are at 21mm, so 22.5 mm would be the minimum with for each connector. That would yield 900mm total width, which seems to fit the MSO5000 it seems. Using a ribbon extension cord is an option, but defeating the purpose of course

But if you find a mini-hdmi port on lcsc we can talk

What is spacing like on the DSO900? That USB connector is awfully close. I was thinking of doing double sided connectors (J1 J2 top, J3 J4 bottom, but those solder lugs get in my way. Offsetting things so both holes overlap, e.g. 2 connectors in 1 hole is an option, just not solderable one. Getting connectors without the lugs is an option, but makes it much to easy to 'rip off'...

I suppose a nother option is an ugly one, current design for the MSO5000, an asymmetrical for the DSO9000, and have it stick out only to the right side. Since the boards carry no components, they are cheap as butt of course, just the design effort.

8 cables is still too much for most of my tasks and still a big-ish cable. Also, those flat cables aren't differential cables, which is why I dislike them. 4 was the sweetspot for me, not just because hdmi has exactly 4 differential channels, but also because 4 is what you'd use for i2c + irq, or SPI + irq etc.

Agree that 8 signals plus 8 GND wires is a lot already. I am not sure why all the individual GNDs would be needed though. My preference for an 8-signal pod would be a 2*5 pin connector (8 signals, 2 GND). That also works well with an IDC connector and colored ribbon cable, with the colors nicely matching the channel numbers.

I think this also comes from the fact, that you may want to have a (coax) wire per signal, and connect each individually to power and signal? Use nice coaxial mini cables? idk, i'm not EE enough (at all) to know what's the better design idea here. For me, using a single row or double row header doesn't make a difference, and I think a 5 pin (or 6) single row might actually be wider then the HDMI plug

I think [...] nikki's v3 are then just what you are after.

Nikki Smith did an updated version of the low-cost (TTL/CMOS) probe only, right -- or did I overlook something? I definitely want a probe with the large voltage range and configurable threshold provided by the LMH7324, since one of my use cases is work on vintage (tube) computers with 20V logic levels.

Very true, it was the first design I looked at actually, because it was in kicad, and I had forgotten about dren.dk's, which I re-found and used to do the LM variants

The design by @dren.dk is the configuration I personally like best, https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/msg2316423/#msg2316423. It needs some work though: Some signal polarities are flipped due to early mis-information about the 50 pin connector's pinout, and he did not bother with length matching of the traces.

But I am in no rush -- will wait how your design pans out, and probably borrow (and use in duplicate) your very nice LMH7324 pod layout. 

Keeping the HDMI connector on the pod isn't unreasonable, because you can't make the pod much smaller anyway, as most space is used by those 2012's that are needed. You could use smaller components there, but then traces could become an issue ...

Making the PCB wider might also run into collisions with the connector on its left -- even more so on the DHO900, which has a USB jack quite close to the logic analyzer port. Maybe look into mini-HDMI or mini-DVI again?

Why not just use vertical ones?!
Previously, I also suggested mini-HDMI and mini-DP, but after looking at the range of cables available I agreed that the ordinary HDMI is the best solution... since slim connectors, flat or soft versions of cables are not even available for mini-HDMI / DP / DVI ...unless you're a fan of cables that look like a garden hose on your table 

... that'll probably mean I have to do my differential lines, again, and the longest one will probably be ending up even longer :S

If you going to redo all differential lines again )) pls look closely at the upright HDMI sockets I've already mentioned before. Then you won't have to make a board that looks like a palm tree. And all four HDMI sockets can fit on a pcb in the width of a 50-pin header.

I actually had considered those as well, (I need HDMI connectors for another project actually, and I really wanted a normal and a reverse (e.g. upsidedown) HDMI connector) but these things are almost impossible to source ...

So the vertical ones, are ugly :p and then stick out either at the top, or the bottom (and I can't place the LED in the center ) But yes on all other points. But the breakout board can be done in various versions :p

Not that cost is the major driving force (well the topic suggests otherwise), the vertical ones do cost 10x more then the normal ones (65c vs 7c)

Also, I'm not convinced it would make layout any easier, the board might end up being even longer due to the size of the connector, and on top of that the connector sticks out quite a bit, and we still need some jigglies to route the pins ...

So while I certainly feel the challenge, I'm worried about its use/success :p Unless I hear a lot of shouts to do it anyway :p But feel free to try I'd share my PCB file, but the forum won't let me so i've renamed it to .txt

[mwb1100]

I've dived a bit deeper into the MSO5000 look and made several touches... now it definitely looks in its authentic style.

Those do look nice!

[oliv3r]

Them new dimensions look something like this, 85mm it looks like atm, dunno if i can route it though

[ebastler]

Thanks for sharing the draft. For the DHO900 series, 85 mm would already be too wide, I'm afraid. As mentioned earlier, I don't have the scope (yet). But I took a photo from the net and used the connector width for scale -- attached.

The circuit board itself would probably already get in the way of inserting a USB stick or plug. If you add an enclosure for the breakout board or an HDMI plug in the leftmost position, it would definitely block the USB port.

LCSC do offer mini- or micro-HDMI connectors, by the way -- they just don't put that in the part name and have no way to filter for them...    Part numbers C2962409, C2962410, C720620 for example are all micro-HDMI connectors which are in stock and cost around $0.50 each. C2962409 and C720620 are also available for JLCPCB's assembly service. Not the friendliest parts for PCB layout though: Those pads are fine-pitched, and I don't see a way to get to the inner row without dropping down to another layer.

Edit: Switching to mini-HDMI would add a bit of parts cost, both for the jacks and the cables. But not significant compared to the LMH732x cost, I'd say. If you don't want to bet on mini-HDMI entirely, there could always be two versions of the breakout board. Probes should keep the full-size HDMI connector in any case, since cables with mini-HDMI on both ends seem very uncommon.

Edit²: Removed the picture, since the scale was not correct. See UK's post below for a corrected picture, which shows an even bigger interference.

Edit³: Oops, the HDMI part numbers above are actually micro HDMI (type D), it seems. They would definitely fit, but may be unnecessarily finicky (both from a layout perspective, and regarding handling/robustness of the plugs). Proper mini-HDMI (type C) connectors are available too, e.g. C2682170. More layout-friendly since they bring all pins out in a single row. Also they are mechanically more sturdy than the micro variant, and should be small enough to fit the four connectors on a breakout board which is not wider than the 2*25 pin port.

[ebastler]

One more comment, if I may, regarding the LMH7324-based pod from reply #155:

The blocking capacitors for the various supply voltages are place a bit too far away from the LMH7324, for my taste. Especially when considering that we are already making compromises with the inductance by using the larger 0603 parts and 100 nF caps only (as used by Rigol too), vs. the (additional?) 10 nF suggested '7324 datasheet.

If you drop the differential output signals down to another layer right away, you would have room for the capacitors directly to the left and right of the '7324. You could bring the differential signals back to the top layer in a convenient place, just below the RN1 and RN2 arrays. That would also allow you to use arrays for the 220 Ohm termination resistors, placed just below RN1 and RN2 respectively.

Oh, and one more thought: When length-matching the four channels on the pod, it should be sufficient to make the total of "trace length on the input side + differential trace length on the output side" equal for all channels. It looks to me like, at the moment, you have separately balanced everything on the input side, and also on the output side. Maybe you can save a few wiggles and some PCB space?

[UK]

But I took a photo from the net and used the connector width for scale -- attached.

Your illustration has a bit of a smaller scale... here is a real scale of 85mm, and a vertical port illustration as well.
Still do not realize why you think that vertical HDMI ports look ugly since most of the Rigol scopes have vertical USB ports on their front panels, even Rohde & Schwarz have the same.

[ebastler]

Your illustration has a bit of a smaller scale... here is a real scale of 85mm, and a vertical port illustration as well.
Still do not realize why you think that vertical HDMI ports look ugly since most of the Rigol scopes have vertical USB ports on their front panels, even Rohde & Schwarz have the same.

Indeed, thanks for double-checking. I'll remove my attached picture since it is misleading; not sure where my scale error crept in. So the collision with the USB port is even worse.

What I dislike about the vertical ports is not the vertical orientation of the plugs themselves, but the fact that they sit so low (or high). All other connectors on the front are nicely aligned to the same height. That's just aesthetics and personal taste, however. The fact that the PCB will have to be deeper to accommodate the vertical jacks, and hence the plugs and cables would stick out further, does have handling implications though. Especially relevant for users who have the scope on a shelf or stacked on top of other instruments, or mounted on a VESA arm for the DHO900: In all these configurations the cables get in the way when you reach up to the touch screen, hence should protrude as little as possible.

[UK]

Aesthetics can be easily achieved just with top-oriented HDMI sockets and IDC connector under the pcb, that also make the board more flush with the panel 

[ebastler]

That could work. But apparently you need an extra-tall connector to reach into the scope, at least for the MSO5000. dren.dk used this arrangement in his design and chose this somewhat exotic connector: https://www.mouser.dk/ProductDetail/200-ESQ12523LD

Edit: What's wrong with mini-HDMI? 

[UK]

Edit: What's wrong with mini-HDMI? 

1. It's double as weaker than full-sized HDMI, while HDMI itself is not the strongest one.
2. Poor range of cables, their availability, and a bit higher price.

So I prefer to pay extra once for a taller IDC header than for useless mini-HDMI cables if this could count as an argument.

[ebastler]

Edit: What's wrong with mini-HDMI? 

1. It's double as weaker than full-sized HDMI, while HDMI itself is not the strongest one.
2. Poor range of cables, their availability, and a bit higher price.

So I prefer to pay extra once for a taller IDC header than for useless mini-HDMI cables if this could count as an argument.

Both are valid points to consider, of course, but I don't see show-stoppers there. Mini HDMI is specified for 5000 plugging cycles vs. 10000 for full-size; seems more than enough for me. (Remember, you are not allowed to hot-plug the Rigol logic probes anyway!) And four cables including shipping start from 8.50€ on AliExpress or 12€ on Amazon, and there are many offers.

So I don't know about "useless" for mini-HDMI... But isn't it nice that we can have different breakout boards easily, all using the same pods with full-size HDMI plugs? 

[UK]

Mini HDMI is specified for 5000 plugging cycles vs. 10000 for full-size; seems more than enough for me. (Remember, you are not allowed to hot-plug the Rigol logic probes anyway!)

Weaker meant not about plugging cycles, but the rigidity and strength of the connection, as well as the gripping force of smaller contact pads... since that's not a connection behind your TV (where nothing happens), it is a workbench and you can easily do !!!hot-unplug!!! just by accident while using the LA. That's why earlier I suggested a full-sized DP-port with its fixing feature.

Summarizing the arguments above, reducing the size of the connector increases the chance of accidents!

So I don't know about "useless" for mini-HDMI... But isn't it nice that we can have different breakout boards easily, all using the same pods with full-size HDMI plugs? 

All my photo and video stuff use micro-DP or micro-HDMI and it is more common nowadays, several 4th and newer 5th PIs also use micro-HDMI... that's why it's useless cable.

And four cables including shipping start from 8.50€ on AliExpress or 12€ on Amazon, and there are many offers.

When I'm talking about availability I mean I don't want to wait about a month for delivery from Alixresss

After all, if we back to the beginning main oliv3r's point was the versability when you can take any HDMI cable lying around and use it with LA and that's really cool! And mini-HDMI is not cool at all, except for the size of the connector.... moreover, overall savings are just a couple of millimeters at the sacrifice of reliability and rigidity of the connection.

[ebastler]

Alright -- many of these aspects are a matter of personal preferences, I think.

I would definitely prefer to have a complete set of probes, cables and grabbers in the drawer anyway, so re-using existing cables is not important to me. While the micro-HDMI connectors feel flimsy to me, mini-HDMI seems sturdy enough. And yes, I would probably also be too impatient to wait for AliExpress delivery; so I'd spend the extra 3.50€ to get four cables from Amazon...

Anyway, the nice thing is that we don't need to make a hard-and-fast decision here, but can have both versions of the breakout board. If oliv3r prefers a different solution, I could always roll my own mini-HDMI version. (Or go with the 2*8 probes and fine-pitch ribbon cable; still pondering on that decision...)

[oliv3r]

One more comment, if I may, regarding the LMH7324-based pod from reply #155:

The blocking capacitors for the various supply voltages are place a bit too far away from the LMH7324, for my taste. Especially when considering that we are already making compromises with the inductance by using the larger 0603 parts and 100 nF caps only (as used by Rigol too), vs. the (additional?) 10 nF suggested '7324 datasheet.

I got them as close as I could, there's traces underneath for power already, so dropping them isn't an option really. The caps are 6mm away, which I admit is further then I'd prefer too. Also, I really wanted to avoid via's, as that introduces other problems of course. There's always the possibility to add extra caps at the bottom though, like what dren.dk did, but I didn't want to compromise on the heat dissipation ability, as the bottom plane is where the ground plane gives the heatsink, adding those capacitors reduce that by quite a bit.

The only real alternative I can come up with, is route the signals on the left/right outside, and keep the top area for the capacitors, but that would make the traces considerably longer, about 3x as long is my guess. So then I ask you, is that worth it? Is it okay to have traces that are 3x as long?

oth, they are on the differential side, and adding a few cm shouldn't be a big issue. Let me mull on that for a bit.

If you drop the differential output signals down to another layer right away, you would have room for the capacitors directly to the left and right of the '7324. You could bring the differential signals back to the top layer in a convenient place, just below the RN1 and RN2 arrays. That would also allow you to use arrays for the 220 Ohm termination resistors, placed just below RN1 and RN2 respectively.

Oh, and one more thought: When length-matching the four channels on the pod, it should be sufficient to make the total of "trace length on the input side + differential trace length on the output side" equal for all channels. It looks to me like, at the moment, you have separately balanced everything on the input side, and also on the output side. Maybe you can save a few wiggles and some PCB space?

All traces, from the 50 pin connector, to the output pin, should all be exactly the same length for each signal I didn't length match pairs only, For obvious reasons, if I measure a 2 channel signal, across 2 pods, I don't to care which input is matched, but want to ensure the delay is identical everywhere. That's why some of the lines look a bit weird, while not being snakes, because they are length matched too.

[oliv3r]

But I took a photo from the net and used the connector width for scale -- attached.

Your illustration has a bit of a smaller scale... here is a real scale of 85mm, and a vertical port illustration as well.
Still do not realize why you think that vertical HDMI ports look ugly since most of the Rigol scopes have vertical USB ports on their front panels, even Rohde & Schwarz have the same.

Very true just the parts themselves I suppose, and it'll make the breakout board 'fat' :p idk, just a feeling if anything.

I'll print the current draft on paper, and see how it fits on the mso5000; doing a mini HDMI breakout for the DSO900 is a fun exercise and nice to have. The vertical jacks though, they make sense logically, as it also saves on using via's :p but the extra depth, extra height put me off. I even liked the vertical connector idea, but those special IDC connectors make me a bit cringe :p

So with all the feedback, I'll start again, bring caps closer, increase the width to fit the plastic, do a mini hdmi variant :p

edit: Suppose if you've done it 8? times, it goes a lot faster :p

[ebastler]

All traces, from the 50 pin connector, to the output pin, should all be exactly the same length for each signal I didn't length match pairs only, For obvious reasons, if I measure a 2 channel signal, across 2 pods, I don't to care which input is matched, but want to ensure the delay is identical everywhere. That's why some of the lines look a bit weird, while not being snakes, because they are length matched too.

I did not express my thought well, I'm afraid. I realize that you have properly length-matched everything, and that it must have taken a lot of tweaking!

What I meant to say is that you can potentially simplify the length-matching. It looks to me like, on the pod PCB, you have (a) length-matched the 4 signal traces from the 2*4 connector to the LMH7324, and (b) also length-matched the 8 signal traces from the LMH7324 to the HDMI connector. But the requirement is only that the sum "length of trace before + length of trace after" the LMH7324 need to be matched between the four channels. So two of the channels may have shorter traces from the input connector to the near side of the LMH7324, and compensate by having longer traces from the LMH7324 to the HDMI.

This thought doesn't matter if you do not need to touch the layout any further; it is clearly good as it is. But if you needed to move things around, get the capacitors closer or such, it might help to work with that relaxed constraint, because it can probably reduce the overall trace lengths and wiggles somewhat.

I got [the blocking caps] as close as I could, there's traces underneath for power already, so dropping them isn't an option really. The caps are 6mm away, which I admit is further then I'd prefer too. Also, I really wanted to avoid via's, as that introduces other problems of course. There's always the possibility to add extra caps at the bottom though, like what dren.dk did, but I didn't want to compromise on the heat dissipation ability, as the bottom plane is where the ground plane gives the heatsink, adding those capacitors reduce that by quite a bit.

OK, I have not seen the inner layers of course. If they are too busy, my suggestion may be impractical -- never mind!

I would also prefer to keep the bottom side free of components -- better heatsinking, more mounting options, also easier to home-build.

[oliv3r]

All traces, from the 50 pin connector, to the output pin, should all be exactly the same length for each signal I didn't length match pairs only, For obvious reasons, if I measure a 2 channel signal, across 2 pods, I don't to care which input is matched, but want to ensure the delay is identical everywhere. That's why some of the lines look a bit weird, while not being snakes, because they are length matched too.

I did not express my thought well, I'm afraid. I realize that you have properly length-matched everything, and that it must have taken a lot of tweaking!

What I meant to say is that you can potentially simplify the length-matching. It looks to me like, on the pod PCB, you have (a) length-matched the 4 signal traces from the 2*4 connector to the LMH7324, and (b) also length-matched the 8 signal traces from the LMH7324 to the HDMI connector. But the requirement is only that the sum "length of trace before + length of trace after" the LMH7324 need to be matched between the four channels.

Yeah, I thought of that too, but that's actually harder, because then you need to do math a lot kicad can't relate and sum traces between components. Also the 'win' there is minimally anyway, but a descent idea anyway.

I'll try to route the traces around the capacitors, to get them closer. I realized, the extra 1 - 2 cm are insignificant, as a) they are differential digital signals, and b) look at the wiggles on the breakout board, I'm not carying about length there either ...

Regarding the HDMI vs mini/micro HDMI discussion, before the raspberry pi, mini-hdmi is something I always thought of, as those cheap tablets used to have them, so there always was some availability. But with the PI, getting cables might actually be quite feasable, so micro HDMI might not be that weird to aim for. I'll have to look at the pinout, but routing may not be a problem either, as the signal traces may be at the top row, and the bottom row be the grounds.

So then, mini-hdmi or micro-hdmi I wonder, they cost about the same, so that's not the issue.

edit: The signals are not all on the top, so routing would be much more painfull, so for now, i'll try mini-hdmi

[ebastler]

So then, mini-hdmi or micro-hdmi I wonder, they cost about the same, so that's not the issue.

Technically, mini-HDMI is probably the better choice: A bit sturdier if one bumps against the plugs by accident, and small enough to fit all four connectors onto a PCB not wider than the scope's port.

Future-proofing might speak in favor of micro-HDMI. As devices keep getting smaller, micro-HDMI is probably taking over and mini-HDMI cables will become harder to get in the long run. But I would not be overly concerned about this: You don't need to plan for a 10-year production lifecycle, and if push comes to shove someone could always add a micro-HDMI breakout board later.

[oliv3r]

How do we feel about this? In terms of dimmensions, the PCB itself is now 68mm wide

[ebastler]

How do we feel about this?

 

[UK]

How do we feel about this?

It looks neat, but it also looks like a big lever and possible strain on the scope port... which will clearly affect its service life.

I even liked the vertical connector idea, but those special IDC connectors make me a bit cringe :p

Is there any real reason for that cringe?! it definitely will put less strain on the scope port.
Also, LEDs can be more visible from the front view, especially while using the DHO900 on the vesa mount.

[oliv3r]

Hmm, that mini-HDMI part is intended to be 'in-pcb' mounted, e.g. requiring a cut-out. If you can find another mini-hdmi port that's 'just flat' that'd be good

How do we feel about this?

It looks neat, but it also looks like a big lever and possible strain on the scope port... which will clearly affect its service life.

I even liked the vertical connector idea, but those special IDC connectors make me a bit cringe :p

Is there any real reason for that cringe?! it definitely will put less strain on the scope port.
Also, LEDs can be more visible from the front view, especially while using the DHO900 on the vesa mount.

The cringing part is that it's quite deep, but more importantly, it's a single-supplier part, it costs 10 times more then a regular connector (9 euro's a piece), will make routing probably quite hard, also because it's a through-hole part.

Yes, the led's visibility will be better, but then there's also 'side-entry' RGB leds. I simply used this one because I used it in a different project (and it's nice and big, side entry RGB's tend to be super small)

[UK]

I agree with you point. I've just recall that also already used 'side-entry' leds on several projects.

[ebastler]

Hmm, that mini-HDMI part is intended to be 'in-pcb' mounted, e.g. requiring a cut-out. If you can find another mini-hdmi port that's 'just flat' that'd be good

LCSC part number C2682170, you mean? Doesn't look to me like it would need a cutout. Were you looking at the same drawings?
https://datasheet.lcsc.com/lcsc/2110112030_XKB-Connectivity-A71-05H4-111N1_C2682170.pdf

[oliv3r]

Hmm, that mini-HDMI part is intended to be 'in-pcb' mounted, e.g. requiring a cut-out. If you can find another mini-hdmi port that's 'just flat' that'd be good

LCSC part number C2682170, you mean? Doesn't look to me like it would need a cutout. Were you looking at the same drawings?
https://datasheet.lcsc.com/lcsc/2110112030_XKB-Connectivity-A71-05H4-111N1_C2682170.pdf

No, I used the wrong part, well a different part, which did have the cutout I saw the name in the pdf, which made me trigger that it was the wrong one. I have too many HDMI parts in my lcsc library now :p

[oliv3r]

Anyway, lets break down our options for a moment.

'top full-szie 2x2' entry:
cons:
* requires expensive extra deep/long IDC connector, hard to source, single supplier
* vertical HDMI connectors sticking out quite a bit to the front
* 'base' quite 'high' (top-bottom)
* vertical HDMI connectors have many connection pins, but put a lot of strain on the connector
pros:
* easily fits 4 connectors
* standard leds easily face forward
* strain on the connectors is more equally distributed?

vertical HDMI connectors
cons:
* increases height (makes the breakout fat) and sticks out further due to their longer length
* leds sit next to the connector, making it harder to identify 'is it the one to the left or right'
pros:
* makes all connectors fit nicely

mini HDMI connectors
cons:
* cables are harder to source
* connections are less strong due to the more fragile connector

micro HDMI connectors
cons:
* Much harder/more ugly to route
* much more fragile
* cables not the easiest to source (but certainly possible)

full HDMI connectors
pros:
* easier to route
* much more robust
cons:
may not fit on non-mso5k

(I'm sure we can increase and work on this list more :p) but for now, I think just doing two layouts, mini and full boards. We can always do a 3rd or a 4th too :p the breakout boards are after all the easiest to do. If for example you have both an MSO5k and a DSO900, you may get one each or just use 2x2 one

[ebastler]

for now, I think just doing two layouts, mini and full boards. We can always do a 3rd or a 4th too :p the breakout boards are after all the easiest to do. If for example you have both an MSO5k and a DSO900, you may get one each or just use 2x2 one

Thanks! I agree that having two options, mini and full-size HDMI, should cover all bases.

For the full-size version, I quite like UK's 2*2 proposal. Maybe the exotic, tall 2*25 connector can be avoided by simply stacking two regular connectors and glueing them together? For the HDMI connector, C168715 looks like the only LCSC part which is meant to be mounted that way. (They also have C2962411 and C711355, which are sold for SMD mounting on a PCB edge but could probably be "abused" as vertical through-hole parts.)

Those vertical connectors should get some mechanical support from a 3D-printed enclosure. But I trust UK will find a stylish solution there! 

[oliv3r]

for now, I think just doing two layouts, mini and full boards. We can always do a 3rd or a 4th too :p the breakout boards are after all the easiest to do. If for example you have both an MSO5k and a DSO900, you may get one each or just use 2x2 one

Thanks! I agree that having two options, mini and full-size HDMI, should cover all bases.

For the full-size version, I quite like UK's 2*2 proposal. Maybe the exotic, tall 2*25 connector can be avoided by simply stacking two regular connectors and glueing them together? For the HDMI connector, C168715 looks like the only LCSC part which is meant to be mounted that way. (They also have C2962411 and C711355, which are sold for SMD mounting on a PCB edge but could probably be "abused" as vertical through-hole parts.)

Those vertical connectors should get some mechanical support from a 3D-printed enclosure. But I trust UK will find a stylish solution there! 

I wouldn't dare putting all those cable stresses on an SMD footprint, but without further ado, the mini HDMI version

One thing I just realized, is that I didn't match the PCB size, but then it also shouldn't matter so much, as the width is different anyway, so having the same depth doesn't add any value.

I did swap the LED pins on the HDMI connector, so I'll have to go back to the other bards and fix that, but still, I think this came out well.

[ebastler]

That looks very nice and tidy! 

When I mentioned the "board edge" HDMI connectors, that may have read a bit confusing. If you look at the drawings for the three part numbers I mentioned, you will find that they all look very much the same, but the manufacturers give different footprints for them: One with vertical mounting, and through-holes for the mechanical mounting tabs as well as all the pins. The other two for mounting horizontally on the board edge, with the PCB between the two rows of pins, and SMD mounting only. But the parts seem to be more or less the same, so all three could probably be mounted vertically (with through holes).

Anyway, as long as the C168715 part is in stock, that's probably the one to get, because one can be reasonably sure that the footprint is correct.

[UK]

Those vertical connectors should get some mechanical support from a 3D-printed enclosure. But I trust UK will find a stylish solution there! 

For sure!

C168715 looks like the only LCSC part which is meant to be mounted that way.

Here you go, C5204145 , C2682172 and short one C711353

I think this came out well.

That's true! May be I missed that but why you didn't route channels D0 and D16?

[ebastler]

C168715 looks like the only LCSC part which is meant to be mounted that way.

Here you go, C5204145 , C2682172 and short one C711353

Oh, nice! It is reassuring to see that there is a larger selection. I had scanned through the thumbnail pictures too, not trusting LCSC's keywords, but did not see (or recognize) those.

I wonder what the "brick nogging" tag means? Is that a standard industry term or the unexpected result of a Chinese-to-English translation?


Edit: Ah....

As a native Chinese speaker, "brick nogging" is gibberish and completely incomprehensible to me.   I was curious and just looked it up, apparently it was a mistranslation of "立贴".
"立" means "standing" or "vertical", and "贴" is the short-hand for "贴片", which means "pick-and-place" or "SMD", so it just means "vertical SMD".

[oliv3r]

So here's the new LM7324 POD with the capacitors hugging the chip as closely as possible.

One thing I just came to realize though, is that the pin-order on the POD's are all 3, 2, 1, 0. This was due to the breakout board, swapping that order makes routing really really hard, as all lines cross each other. I don't know how the original pod solves this, or if the order is also backwards? But the solution is of course simple, flip the pod around but that puts the led on the bottom, and since I don't want to do dual-sided components ... maybe I'll do the leds on both sides ....

Flipping the connector btw won't help that much, because it's a side-entry connector, so flipping it just puts it up-side down, but pin 0 is still on the right ...

May be I missed that but why you didn't route channels D0 and D16?

I don't understand, they are routed aren't they?

[ebastler]

So here's the new LM7324 POD with the capacitors hugging the chip as closely as possible.

One thing I just came to realize though, is that the pin-order on the POD's are all 3, 2, 1, 0.

Cool, that layout looks really nice and tight now! 

I would not worry at all about the bit order. To the contrary: Isn't that how multi-digit binary numbers should be written, low bit on the right? 

[UK]

I don't understand, they are routed aren't they?

I've read the mask on the board with mini-HDMIs - 1-3,4-7,9-11,12-15... looks like 0 and 8 are missing

One thing I just came to realize though, is that the pin-order on the POD's are all 3, 2, 1, 0.

I forgot to tell you last time, that the length of the PCB should be extended for proper placement of the 8p socket, since it has to be lying on the PCB (at least half of it) and not floating in the air. Because anyway we have this empty space in the shell under the 8p socket. So then if the length will be extended and we get additional PCB space, why just not reroute the pins order on the PCB backside like this?

After all, we have 6 spring-connection points for each channel, so 2 more VIAs should not drastically affect on the signal.

[oliv3r]

I don't understand, they are routed aren't they?

I've read the mask on the board with mini-HDMIs - 1-3,4-7,9-11,12-15... looks like 0 and 8 are missing

ohh, fair point, the silkscreen is wrong

One thing I just came to realize though, is that the pin-order on the POD's are all 3, 2, 1, 0.

I forgot to tell you last time, that the length of the PCB should be extended for proper placement of the 8p socket, since it has to be lying on the PCB (at least half of it) and not floating in the air. Because anyway we have this empty space in the shell under the 8p socket. So then if the length will be extended and we get additional PCB space[/quote]
I wanted to keep the PCB length <5cm because that's where you get the cheaper rates with the board houses, or you can put 2 on a 10x10 board
I realize its floating in mid air, and would only be held in place by the solder and the housing, which is a bit weird, but just more economical I suppose. I can now put 3 pod designs on a 10x10 PCB order

, why just not reroute the pins order on the PCB backside like this?

To flip the order? Yeah I was thinking that too, though it would also mean length matching traces again etc. And, having a MSB - LSB layout isn't that bad :p

After all, we have 6 spring-connection points for each channel, so 2 more VIAs should not drastically affect on the signal.

Yeah, I'll sleep on it some, though those connection points etc are all on those differential channels. This is now on the 'more anloguey' input. fair nuff, it's a digital input in the end, so an additional via won't hurt of course.

So it would end up something (a little prettier) like this, length matching should be duable, I just don't like the fact that I have to use really thing traces now (0.25mm), because much more won't fit between those pins of course ...

[ebastler]

So it would end up something (a little prettier) like this, length matching should be duable, I just don't like the fact that I have to use really thing traces now (0.25mm), because much more won't fit between those pins of course ...

That should work. You can make the traces nearly twice as thick as they currently are and still keep the minimum distance from the pins, it seems.

And you should not need much extra room for length matching in that area: Channels 0 and 3 have extra wiggles above the voltage dividers anyway; if you straighten those, the lengths should be reasonably well-matched already?

[UK]

I wanted to keep the PCB length <5cm because that's where you get the cheaper rates with the board houses, or you can put 2 on a 10x10 board

I don't understand why you even need this since previously you told us you won't mass produce them... currently, every PCB manufacturing service offers a minimum 5pcs of PCB which is 4 pods + 1 extra... what a point to place 3 pcs on 1 PCB if you do not plan to get in total 15 pods

You can make the traces nearly twice as thick as they currently are and still keep the minimum distance from the pins, it seems.

Totally agree!
You can route them like this to get nearly perfect length matching.

Edit: really forgot we have here 4 layer PCB 

[mwb1100]

A little bit of an interjection:  I'm really a software guy so pretty much everything here is over my head, but I have been loving following this thread.  Seeing the issues involved in designing a layout AND seeing the amazing collaboration going on here is just fantastic!

[oliv3r]

So while fiddling with it, it wasn't actually that hard and not even that ugly. I've put the traces all in the middle, so that a) ground planes help, and b) I did really need that room.

I wanted to keep the PCB length <5cm because that's where you get the cheaper rates with the board houses, or you can put 2 on a 10x10 board

I don't understand why you even need this since previously you told us you won't mass produce them... currently, every PCB manufacturing service offers a minimum 5pcs of PCB which is 4 pods + 1 extra... what a point to place 3 pcs on 1 PCB if you do not plan to get in total 15 pods

Well I also want some spare/give away's :p and .. options/premature optimization :p My OCD also won't cope going just a few mm over 5cm board size

As for mass-producing, if there's tons of people wanting these boards, I might order a bigger quantity of course, but I won't be going into business selling these, that's true.

You can make the traces nearly twice as thick as they currently are and still keep the minimum distance from the pins, it seems.

Totally agree!
You can route them like this to get nearly perfect length matching.

Yep, I played with it a bit, and got to 0.4mm which isn't too horrible I thought.

The wiggles above the voltage dividers are needed, because the center two channels come from the top of the chip, so need to go all the way from the top, to the bottom.

A little bit of an interjection:  I'm really a software guy so pretty much everything here is over my head, but I have been loving following this thread.  Seeing the issues involved in designing a layout AND seeing the amazing collaboration going on here is just fantastic!

Same here, I couldn't properly design this, I don't know enough about EE, but we got the reverse engineered pods and earlier designs, that I'm hopping will prove to be true :p

It's mostly just me taking other peoples great idea's and re-spinning them, listening to ebastler and UK for feedback/wishes

P.S. I asked the admin/moderate to spin this thread into its own forum post, so lets see if that'll happen

[ebastler]

The wiggles above the voltage dividers are needed, because the center two channels come from the top of the chip, so need to go all the way from the top, to the bottom.

No, I don't think they are needed. They are in channels 0 and 3, right? And now you have created additional wiggles in channels 1 and 2 just above the 2*4 plug. They pretty much even out, so just do away with all four of them -- that's what I meant.

Otherwise, great work, and I am excited to see the pod getting its final touches! 

[oliv3r]

The wiggles above the voltage dividers are needed, because the center two channels come from the top of the chip, so need to go all the way from the top, to the bottom.

No, I don't think they are needed. They are in channels 0 and 3, right? And now you have created additional wiggles in channels 1 and 2 just above the 2*4 plug. They pretty much even out, so just do away with all four of them -- that's what I meant.

So on the top-size, from the chip to the resistor/capacitor network, there's a wiggle to compensate for the length of channel 1 & 2 which come from the top of the chip, and run on the bottom side. So all traces from the chip, to the network are all 4 in identical length.  The wiggles after the network, is to match the length of the outputs going to the 2x4.

There is one thing that isn't properly matched though, just because I don't know how, and that's the length of the wires in the network, they should be the same but I wouldn't be supprised there's an error inthere, especially in the lm7234 pod, as the network isn't oriented identically, to make things fit better (0&3 and 1&2 are identical though). And since the parts aren't perfect tetris blocks (resistors and capacitor 2012's have different sized pads ... go figure.

One tiny advantage of not putting the PCB underneath the connector btw, is that we can put in the connector a bit lower, allowing the pod to be not as fat. I even thought of doing the same as with the 50pin connector, and use an SMD layout, for a straight throughole part and side-mount it ... should fit?

Does require clipping some sticking out legs though ...

[ebastler]

So on the top-size, from the chip to the resistor/capacitor network, there's a wiggle to compensate for the length of channel 1 & 2 which come from the top of the chip, and run on the bottom side. So all traces from the chip, to the network are all 4 in identical length.  The wiggles after the network, is to match the length of the outputs going to the 2x4.

I think we are still not talking about the same traces. Referring to the attached montage, I was looking at the length-matching wiggles indicated by the two smaller circles. They seem to be for channels 0 and 3. And now you have added the wiggles for channels 1 and 2, indicated by the larger circle. These four seem to be of very similar length -- so can't you simply remove all four of them?

Edit -- some further, unrelated comments:

• I like the lowered position of the 2*4 connector; makes the vertical alignment nice and symmetrical.
• Don't forget to change the channel numbers on the top and bottom silkscreen to 0..3!
• Please correct the top silkscreen to say LMH7324.

[UK]

Finally, guys, I found a solution for vertical 50p headers!

Firstly, such headers are not rare at all, it’s just that most manufacturers do not mark them as elevated or extra tall.
Secondly, there not many have in the lineup version 2x25.

Even Pololu produce such headers already many years but only in 2x20 version.

BUT if you try to search directly PC104 long pin, you can get a ton of them, its Chinese OEM headers which are very widely available on many markets... amazon, ebay and of course most cheap prices on aliexpress. There exact option 2x25, but as a rescue option 2x5 also available (that may be staked in row by 5).

The main interesting part is that its high may be easily raised just by adding a plastic part salved from common pin header (pic from Pololu nicely illustrate that).

-------

So now we have an all option for vertical 50p and vertical HDMI sockets 

And as for the vertical HDMI sockets looks like Rigol use C2682172 in their DHO scopes, you can cheek it here... but I think C5204145 definitely more robust.

-------

PS

...is that we can put in the connector a bit lower, allowing the pod to be not as fat.

Extremely like the idea of low-ride 8p socket position! 

[ebastler]

BUT if you try to search directly PC104 long pin, you can get a ton of them, its Chinese OEM headers which are very widely available on many markets... amazon, ebay and of course most cheap prices on aliexpress. There exact option 2x25, but as a rescue option 2x5 also available (that may be staked in row by 5).

Yes, these should work. They don't even need a spacer permanently installed, I think, since there are so many pins to keep them stable. But of course you need some spacer or alignment aid during soldering, to make sure you solder them in at the right height.

These connectors do not have the little tab which ensures you can't plug them in the wrong way. So the PCB will need some clear lettering on the front to show the user which side is up.

EDIT: Or rather, the 3D-printed enclosure will need to provide that lettering. Or one can try and glue a little plastic tab onto the connector which matches the notch on the scope side.

[UK]

These connectors do not have the little tab which ensures you can't plug them in the wrong way.

Yep, it's definitely not a problem and it just could be a part of the shell.

-------

I've made a try to calculate the best dimensions for 2х2 PCB, which taking into account all shell clearances and possible margins, should have a perfect fit with both of the scopes!
Also, I want to point out that 50p header should have a slight vertical offset.

To be honest, now I'm even more interested in the version for DHO900 since I plan to get this cute little scope during the winter holidays 

[oliv3r]

So on the top-size, from the chip to the resistor/capacitor network, there's a wiggle to compensate for the length of channel 1 & 2 which come from the top of the chip, and run on the bottom side. So all traces from the chip, to the network are all 4 in identical length.  The wiggles after the network, is to match the length of the outputs going to the 2x4.

I think we are still not talking about the same traces. Referring to the attached montage, I was looking at the length-matching wiggles indicated by the two smaller circles. They seem to be for channels 0 and 3. And now you have added the wiggles for channels 1 and 2, indicated by the larger circle. These four seem to be of very similar length -- so can't you simply remove all four of them?

But I think we are

The yellow lines are the same four lines for all four channels, that's why the wiggles exist before the input of the resistors and caps. You could probably do some math, and reduce the bottom wiggles from the top wiggles, I certainly grant you this, but it makes it harder to raid/verify/maintain. Now you have identical wherever they are measurable. Also, making it harder, and some wiggles still remain. Also, those 'ears' on the left/right side ... plenty of space for those anyway :p Also looks a little more symmetrical this way

Edit -- some further, unrelated comments:

• I like the lowered position of the 2*4 connector; makes the vertical alignment nice and symmetrical.
• Don't forget to change the channel numbers on the top and bottom silkscreen to 0..3!
• Please correct the top silkscreen to say LMH7324.

check, check, check

[ebastler]

The yellow lines are the same four lines for all four channels, that's why the wiggles exist before the input of the resistors and caps. You could probably do some math, and reduce the bottom wiggles from the top wiggles, I certainly grant you this, but it makes it harder to raid/verify/maintain. Now you have identical wherever they are measurable. Also, making it harder, and some wiggles still remain. Also, those 'ears' on the left/right side ... plenty of space for those anyway :p Also looks a little more symmetrical this way

Alright, I see. You prefer to match all four traces below the divider components, and then also match all traces between the divider and the LMH7324. It will certainly work; it just results in more wiggles on the board than needed. But maybe that's just an obsessive-compulsive thing for me...

[oliv3r]

These connectors do not have the little tab which ensures you can't plug them in the wrong way.

Yep, it's definitely not a problem and it just could be a part of the shell.

-------

I've made a try to calculate the best dimensions for 2х2 PCB, which taking into account all shell clearances and possible margins, should have a perfect fit with both of the scopes!
Also, I want to point out that 50p header should have a slight vertical offset.

To be honest, now I'm even more interested in the version for DHO900 since I plan to get this cute little scope during the winter holidays 

While I get the excitement for the vertical ports, ignoring for a moment that I used the wrong part :p, where in the world would we put the actual traces? I think even going full smd (which still requires the same amount of via's just for the holes to reach the other side, or go hybrid (smd HDMI connectors, throughole IDC connector (or vice versa) we still need a ton of via's just to route all those signals. I've also tried two options, one logical (1, 2, 3, 4) and one shortest trace (2, 1, 4, 3), which gives a rats-nest mess. What I did in the end, per your request, ordering the ports, was only possible by enlarging the PCB by half or full cm, which isn't really an option in this case?

I'd route if if I had any hopes, but with these parts, it would require going with the tiniest pitch, and probably forget about doing length-matched traces ...

[oliv3r]

The yellow lines are the same four lines for all four channels, that's why the wiggles exist before the input of the resistors and caps. You could probably do some math, and reduce the bottom wiggles from the top wiggles, I certainly grant you this, but it makes it harder to raid/verify/maintain. Now you have identical wherever they are measurable. Also, making it harder, and some wiggles still remain. Also, those 'ears' on the left/right side ... plenty of space for those anyway :p Also looks a little more symmetrical this way

Alright, I see. You prefer to match all four traces below the divider components, and then also match all traces between the divider and the LMH7324. It will certainly work; it just results in more wiggles on the board than needed. But maybe that's just an obsessive-compulsive thing for me...

Heh, my OCD says the same, but then I compromise, or convince myself, it's nicer, cleaner and more symmetric to have every measurable line matched in length. So you can pick any line on the pcb, and find its length matched trace. It just depends how you look at it I suppose

Trust me, my OCD is itching with the thought, I just have to convince my OCD is better then your OCD

[ebastler]

While I get the excitement for the vertical ports, ignoring for a moment that I used the wrong part :p, where in the world would we put the actual traces? I think even going full smd (which still requires the same amount of via's just for the holes to reach the other side, or go hybrid (smd HDMI connectors, throughole IDC connector (or vice versa) we still need a ton of via's just to route all those signals. I've also tried two options, one logical (1, 2, 3, 4) and one shortest trace (2, 1, 4, 3), which gives a rats-nest mess. What I did in the end, per your request, ordering the ports, was only possible by enlarging the PCB by half or full cm, which isn't really an option in this case?

I'd route if if I had any hopes, but with these parts, it would require going with the tiniest pitch, and probably forget about doing length-matched traces ...

Umm, are you sure you have oriented the 2*25 connector the right way round? Isn't the notch, and also pin 1, facing up in the scope?

If it really needs to be flipped around, that might give you a fighting chance at routing the PCB for a "logical" HDMI connector order. It will still be very tight, no doubt about that. I agree that switching to SMD-style HDMI connectors could help a bit. (The "brick nogging" type from LCSC; they would still have through-hole mounting tabs though, which are good for stability but get in the way on all layers.)

Other degrees of freedom are rotating the HDMI connectors 180°, or moving them laterally a bit closer to the middle and moving the LEDs to the outside instead. Not sure whether either of these would help with the routing. The lateral move should at least give you a better symmetry of the trace lengths for the left vs. right connectors, requiring less overall trace length and wiggling.

EDIT: I looked again at the pinout of the 2*25 connector. It looks like it is mirrored, rather than rotated? Pin 1 should be in the upper right, I believe. -- So D0..D3 and D8..D11 will be on the right-hand side of the connector. I would definitely place their HDMI connectors on the right side too; don't see a usability problem with that.

[UK]

While I get the excitement for the vertical ports, ignoring for a moment that I used the wrong part :p, where in the world would we put the actual traces? I think even going full smd (which still requires the same amount of via's just for the holes to reach the other side, or go hybrid (smd HDMI connectors, throughole IDC connector (or vice versa) we still need a ton of via's just to route all those signals. I've also tried two options, one logical (1, 2, 3, 4) and one shortest trace (2, 1, 4, 3), which gives a rats-nest mess. What I did in the end, per your request, ordering the ports, was only possible by enlarging the PCB by half or full cm, which isn't really an option in this case?

I'd route if if I had any hopes, but with these parts, it would require going with the tiniest pitch, and probably forget about doing length-matched traces ...

So we have another challenge here  ...the way it can be done is to implement all of that as a stack of two PCBs assembled by two rows of pins on their wide sides (in the style of Arduino Nano).

Pros: doubling the space, separating PCB for HDMI sockets and 50p header, and as a result easier component placement and routing... and cons: 3-4mm additional stack height, doubling PCB cost and additional 10 mins for soldering pins during final assembly

Multi board PCB or multi level PCB is a very common practice when a complex PCB should be fitted in a very tight space.

[oliv3r]

While I get the excitement for the vertical ports, ignoring for a moment that I used the wrong part :p, where in the world would we put the actual traces? I think even going full smd (which still requires the same amount of via's just for the holes to reach the other side, or go hybrid (smd HDMI connectors, throughole IDC connector (or vice versa) we still need a ton of via's just to route all those signals. I've also tried two options, one logical (1, 2, 3, 4) and one shortest trace (2, 1, 4, 3), which gives a rats-nest mess. What I did in the end, per your request, ordering the ports, was only possible by enlarging the PCB by half or full cm, which isn't really an option in this case?

I'd route if if I had any hopes, but with these parts, it would require going with the tiniest pitch, and probably forget about doing length-matched traces ...

So we have another challenge here  ...the way it can be done is to implement all of that as a stack of two PCBs assembled by two rows of pins on their wide sides (in the style of Arduino Nano).

Pros: doubling the space, separating PCB for HDMI sockets and 50p header, and as a result easier component placement and routing... and cons: 3-4mm additional stack height, doubling PCB cost and additional 10 mins for soldering pins during final assembly

Multi board PCB or multi level PCB is a very common practice when a complex PCB should be fitted in a very tight space.

"But is it worth it", the mini-hdmi breakout board is already smaller afaik

Also, the IDC connector was also the wrong one, it was the female kind, but that flipping of the pins, is a triviality and won't affect the rats nest much

[oliv3r]

subscribing...

I asked the admin to split of the thread, but no reply yet

[UK]

"But is it worth it", the mini-hdmi breakout board is already smaller afaik

Also, the IDC connector was also the wrong one, it was the female kind, but that flipping of the pins, is a triviality and won't affect the rats nest much

It depends, if you want to have more fun - yes, if just finish this project asap - definitely not 

I've already started working on several mini HDMI board shells.

[Mechatrommer]

subscribing...

I asked the admin to split of the thread, but no reply yet

10 pages is still easy to handle and usually like all other threads, the first few pages are the most usefull one anyway, can ignore the rest. ymmv. cheers.

[ebastler]

10 pages is still easy to handle and usually like all other threads, the first few pages are the most usefull one anyway, can ignore the rest. ymmv. cheers.

Well, in this particular thread the first 6 pages focus on a low-cost probe with limited capabilities (TTL/CMOS level only, fixed threshold). Towards the end of page 6, oliv3r presents his project which supports different flavors of probes -- either using the same low-cost TTL/CMOS driver, or using the proper (but expensive) comparators and 10:1 divider front-ends as used in the original Rigol probe.

That might make the overall thread a bit hard to follow; and for the second part one could argue that the thread title is a bit misleading. Also, it would be nice to get the DHO900 mentioned in the thread title, since that new scope uses the same logic probes as the MSO5000.

[oliv3r]

subscribing...

I asked the admin to split of the thread, but no reply yet

10 pages is still easy to handle and usually like all other threads, the first few pages are the most usefull one anyway, can ignore the rest. ymmv. cheers.

Problem is, that this has absolutly no relation to easyeda anymore and I really just hijacked the thread, which isn't nice :p

[oliv3r]

So I ran into one little bit of an issue, the 497 resistor doesn't seem to exist ... I know that the original drawing is reverseengineered and 'measured'. But then I also don't understand the original/intended design (at all) to see what is a good fit replacement.

So for now, I'm going with 499Ohm, which does exist, which is 'close enough', and also fits in the E96 list, so not unlogical to have been used. Same for the 90k8, which will become a 90k9

[ebastler]

So I ran into one little bit of an issue, the 497 resistor doesn't seem to exist ... I know that the original drawing is reverseengineered and 'measured'. But then I also don't understand the original/intended design (at all) to see what is a good fit replacement.

So for now, I'm going with 499Ohm, which does exist, which is 'close enough', and also fits in the E96 list, so not unlogical to have been used. Same for the 90k8, which will become a 90k9

Sure, neither of these should be highly critical, and especially the 49x Ohm resistor is not.

The 90kx resistor forms a 10:1 voltage divider together with the 10k resistor, so the "perfect" value would be 90k0. But who cares about a 1% error in the divider ratio?

The 49x resistor in series with the 3.3pF capacitor forms a bypass for high frequencies. I.e. they will not be attenuated by 10:1 but much less; presumably to preserve exact timing of the signal edges. But I don't see why you couldn't even be 10% off here without creating a problem. (The capacitor will have at least a few % tolerance anyway, so your RC time constant won't be that well-defined.)

[oliv3r]

Towards the end of page 6, oliv3r presents his project which supports different flavors of probes -- either using the same low-cost TTL/CMOS driver, or using the proper (but expensive) comparators and 10:1 divider front-ends as used in the original Rigol probe.

Well that's also part of the reason I went with quad pods, to lower the cost of the probe, not often you need 16 * expensive parts

the quad vs dual LMH's is a cost/availability/performance/original thing. We'd want to have 1 pod that's next to identical of the original, and LMH7324's that might be cheaper/but maybe hotter? Who knows why rigol did what they did

[UK]

Thanks to @sergk for the measurements of the DHO900's LA slot... can say with confidence that it's absolutely the same as on MSO5000.

Almost finished the shell for the mini-HDMI board, but the PCB will definitely require some edits for adding several slots and holes for the screws.
@oliv3r, did you already order the PCBs?

[rdtsc]

If this is to be believed, Esaler currently has 942pcs of the LMH7324SQX/NOPB for $0.92ea.

[UK]

Here is the finished shell for oliv3r's breakout board, firstly, it was a bit tricky to make HDMI sockets look visually vertical and LEDs visible from any angle... secondly, to make a proper shadow line with a safe 1mm margin to the LA slot inner walls and find a good place to securely fasten the shell to the board. It prints really well, you can check a closeup photo, where it was printed out in matte black PLA with a standard 0.4mm nozzle and 0.16 layer height.

Really hope oliv3r will publish the final version of its board soon and I won’t have to recreate it from scratch.

...but the PCB will definitely require some edits for adding several slots and holes for the screws.

@oliv3r pls, check the board outline in the attachment. PCB requires small edits.

[ebastler]

Wow, that looks very cool indeed! Very nice job!

I'm curious: What software are you using to design and to produce those stunning renderings? (Which even include the layer structure of the 3D printer apparently, so the software seems to know about the slicing too?)

[Tarloth]

I asked the admin to split of the thread, but no reply yet

Oliver, UK and eblaster !!!!
​
You took a thread from this forum that had nothing to do with your discussion and invaded it with impunity even though eblaster warned about it several times. YOUR DESIGN AND DISCUSSIONS correspond to another thread about to mimic the original POD with a faster LVDS comparator, here in this thread ANOTHER different design was being discussed, simpler, limited but cheaper in which your ideas and designs DO NOT apply. On top of that, you introduces a lot of confusion in this thread and it is no longer even easy to follow the versions when you filled the last three pages with vanilla connector arguments.

PLEASE, next time respect the other threads that have nothing to do with what you are like to discuss!

[UK]

Freeze! Forum police here! 

[ebastler]

I asked the admin to split of the thread, but no reply yet

Oliver, UK and eblaster !!!!
​
You took a thread from this forum that had nothing to do with your discussion and invaded it with impunity even though eblaster warned about it several times. YOUR DESIGN AND DISCUSSIONS correspond to another thread about to mimic the original POD with a faster LVDS comparator, here in this thread ANOTHER different design was being discussed, simpler, limited but cheaper in which your ideas and designs DO NOT apply. On top of that, you introduces a lot of confusion in this thread and it is no longer even easy to follow the versions when you filled the last three pages with vanilla connector arguments.

PLEASE, next time respect the other threads that have nothing to do with what you are like to discuss!

Next time you might want to ask ChatGPT to word your message. It tends to get the tone about right.

Yes, this discussion of a "proper", comparator-based logic probe has become bigger than Oliver originally expected. So what do you propose we do about it? Users cannot move parts of a thread to a new one; Oliver asked the moderators but they did not get around to it, or did not consider it worthwhile. So what?

As threads on this forum go, I think the past pages have been one of the more productive examples. Something actually gets developed, in a joint effort, with feedback on improvement ideas. Much better than the haggling we get in some other threads. And yes, the connector discussion is highly relevant in this context. Guess what? Using a standard ribbon cable with 50 conductors to the probe sucks.

If you are interested in the cheap solution, since all you want to probe is 5V and 3.3V logic: Buy a complete LA probe on ebay for $75 including cheap grabbers; problem solved.

[Tarloth]

eblaster and UK, You can discuss all you want about the solution you are thinking and off course about the connector variants, but in the appropriate thread, a new one or the original one, not this, and the same eblaster warned about this is not the appropriate thread several times but continues writing in the wrong thread.

In this thread, having daughter boards was not even being discussed, just a simple, inexpensive and direct signal adapter between the grabbers and the oscilloscope. Many of us don't need more than that and we are interested in maintaining the original thread with the ideas from the original thread straightforward.

By the way, I have tons of original pods from HP signal analyzers with higher quality grabbers than cheap one in ebay, and even than the original from Rigol. You can say that flat cables suck but it turns out that they have been used for years by the big brands. Agilent for example still uses flat ribbon in pod's of almost 4GSa/s. It's ok if you don't like them, but for some of us, who think perhaps in more pragmatic (conservative? budget?) terms they seem sufficient for an oscilloscope under $1000 (or 10K by the way). Because of that in this thread the board keep simple.

On the other hand, I don't have to buy a $75 LA because I didn't agree with your point of view! With the same argument I would tell you to go and buy the original Rigol! It's great to discuss alternatives to commercial products, I just ask that they be done in the appropriate threads for each initiative.

The only thing I'm asking you is to respect the threads, and continues arguing in the appropriate one when you originated the discussion. This thread also has a very productive discussion, similar to the one originally proposed by Sr Gandalf but from an even simpler approach.

[Mechatrommer]

as long as discussion circling around somewhat evolution or improvement to the probe, i'm fine... btw, is there any clear diagram rev eng people made about what every single pin does on the MSO5000's 2x25 2.54mm pitch LA connection? (i guess should be the same/compatible with DHO900) all i've seen so far are finished diy probe product... what if i want to make my own LA probe? if there is diagram, i dont have to redo rev eng...

[ebastler]

btw, is there any clear diagram rev eng people made about what every single pin does on the MSO5000's 2x25 2.54mm pitch LA connection? (i guess should be the same/compatible with DHO900)

See below, for example. And yes, it's the exact same pinout on the MSO5000 and DHO900. (The DS1000Z plus has a slightly different connector. Same signals, but more GND pins and hence 68 pins in total, I believe.)

https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/msg2419002/#msg2419002

EDIT: If you want to design your own probe, don't talk about it here or Tarloth will get mad at you... 

[Tarloth]

EDIT: If you want to design your own probe, don't talk about it here or Tarloth will get mad at you... 

eblaster, you are really behaving in a way that is not only dishonest but also quite unfair.

I am NOT saying that discuss about make a version of LA is wrong, I affirm that it's quite positive, I ask only that it be done in the corresponding thread:

* Original thread https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/ (which is where someone started arguing about the USB-C vs mini connector HDMI) attempts to replicate the original Rigol board using high-speed comparators and can adapt to different logic levels. It is the most complete and expensive, and includes several improvements to the original Rigol adapter.

* This other thread https://www.eevblog.com/forum/testgear/ms05000-budget-logic-analyzer-probe-set-design/ started by Gandalf_Sr, it's based on adapting only logic signals (3.3 volt and 5.5 perhaps some other in positive low voltage) but using one board on the oscilloscope side to tidy channels and two independent pods (connected via a flat ribbon cable) with 8 channels. Each board include logic to LVDS converter and a level converter that can even use the voltage present on the analyzed board for flexibility. This design ignores the signals from the oscilloscopes that configure the logic level. Only one logic level for each daughter board,

* This thread, started by S. Pethrukin, is for those who are discussing a signal adapter PCB for 3.3/5 volt logic only, using a 5 volt tolerant digital-LVDS converter. It is a single board budget project, the grabbers go directly to the PCB that adapts the signals between they and the oscilloscope. No differential cables between boards, perhaps a flat ribbon cable from old SCSI drives to connect the board to oscilloscope for more freedom. It is the cheapest of the three threads.

Each thread has a obvious target and budget. Three different ideas with the same objective, BRAVO! But each one has its problems and targets so it is more neat to keep them organized and tidy, but that's why the threads exist in forum.

By the way, YOU notice that this is not the thread to discuss about the diferential connectors between boards in those post

Could you point to those designs you used as a starting point? I had come across a thread once which aimed to do a full-spec replica of the Rigol probe, but it is not this thread here, right?

Answering my own question, since oliv3r seems to drop in only sporadically:

The thread on analyzing and replicating the original MSO5000 logic probe (PLA2216) is here: https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/.

The present thread is the "low cost probe" one, which originally focused on the cheaper CMOS/TTL-level pods only. As mentioned a few posts above, I have found the other relevant thread in the meantime. It looks into using the original LMH732x comparators, and has a few schematics and layout suggestions for those: https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/.

[Simon]

If you can find me a thread  that 10 pages in has stuck band on topic I will devise a medal for you!

[ebastler]

@Tarloth -- you come into this thread complaining and shouting at us, then you follow up with two dissertations. You still have not answered my question in response to your initial complaint: What do you expect Oliver, UK or me to do with this thread now? Delete all our posts?

[Tarloth]

If you can find me a thread  that 10 pages in has stuck band on topic I will devise a medal for you!

Yes, the second link https://www.eevblog.com/forum/testgear/ms05000-budget-logic-analyzer-probe-set-design/

[Tarloth]

@Tarloth -- you come into this thread complaining and shouting at us, then you follow up with two dissertations. You still have not answered my question in response to your initial complaint: What do you expect Oliver, UK or me to do with this thread now? Delete all our posts?

First of all, english it's not my first language (I assume it's not yours either) and sorry if you fell agreded but I ask you for not invaded unrelated thread next time. As answer to my post accuse me of Police (I ask for rule's compliance) and you tell another user that I am against the discussion of new ideas, which is not true, I just asked you for little order and not to continue writing in this thread or in the future not to invade threads not related to their discussion . An user that are interested in the original post need's to navigate several pages unrelated to the topic and perhaps lost information that it's relevant to this low cost solution.

To put in black and white, I intend that if on October 26 you had already detected that this was not the thread to discuss this topic, at least maintain some order and go to discuss in the thread that you yourself said should be used. And if the moderators don't move the posts, at least  don't continue generating discussion pages here that belong to another thread and continue where your topic belongs. It wouldn't be relevant if with the first post hadn't realized that was the wrong thread, but you in particular detected it and reported it at least 3 times and didn't care. That's annoying.

When you just discovered that were on the wrong thread, you could have copied posts to the other thread and deleted these and everything was in order. Now that it's impossible, only if a moderator do that.

Please, respect the topic of a thread, It is a way to respect the discussions of other people and keep the forum organized. It is simply respect for the other people who are discussing other things unrelated to your discussion, that is very interesting and important, but in their corresponding place.

Have you a nice day

[Mechatrommer]

can someone re-explain how 49.9ohm and 220ohm resistors form 1/10X attenuation? i read the original rigol la probe limit is 40V, 1k ohm input impedance? this is mind boggling.
i'm referring to this post: https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/msg2088667/#msg2088667

[ebastler]

can someone re-explain how 49.9ohm and 220ohm resistors form 1/10X attenuation? i read the original rigol la probe limit is 40V, 1k ohm input impedance? this is mind boggling.
i'm referring to this post: https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/msg2088667/#msg2088667

You need to look at the input side of the comparator, with a 10k/(90.8k+10k) divider. You were looking at the termination resistors for the differential output.

[Mechatrommer]

can someone re-explain how 49.9ohm and 220ohm resistors form 1/10X attenuation? i read the original rigol la probe limit is 40V, 1k ohm input impedance? this is mind boggling.
i'm referring to this post: https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/msg2088667/#msg2088667

You need to look at the input side of the comparator, with a 10k/(90.8k+10k) divider. You were looking at the termination resistors for the differential output.

i thought the bottom side is the input, no? so that means, top side is the input?

[ebastler]

i thought the bottom side is the input, no? so that means, top side is the input?

In the schematic in the post you linked to, the inputs are on the left side of the comparator: The probed signal on IN+, the reference level (threshold) on IN-. The relevant voltage divider is on the IN+ signal.

The resistors you talked about (49 Ohm and 220 Ohm) are shown on the right side of the comparator. That's where the two differential output lines are. The resistors do not form a voltage divider; these are termination resistors.

Are you sure you should be considering your own probe design? 

EDIT: Ah, you were now talking about the photo? Better use the schematic if you want to study the circuit design... But yes, on the photo the differential outputs are on the bottom -- which is why there are twice as many connections.

[Mechatrommer]

Are you sure you should be considering your own probe design? 

i'm currently trying to understand this thing inside out while i have time and interest. including evaluating pre-existing diy and original design how and why they do it.. just now trying to find comparator replacement to unobtanium LMH7322 (LMH7324 also not available from the sources i usually buy things from), not an easy task.. currently listing as possible/cheaper replacement ACDMP 607/562/564/567 but they are equally hard to find or expensive. LT1715 is cheaper, but probably crippled and 4ns prog delay may put some people off. what i dislike about pre existing is their form factor, large IDE connectors here and there and right angle connection, i prefer if possible much compact version with nice 3d printed casing... so i'm still evaluating, no conclusion yet, just learning.

In the schematic in the post you linked to, the inputs are on the left side of the comparator: The probed signal on IN+, the reference level (threshold) on IN-. The relevant voltage divider is on the IN+ signal.

ah sorry i didnt notice there is diagram attached below that post. thanks.

[ebastler]

just now trying to find comparator replacement to unobtanium LMH7322 (LMH7324 also not available from the sources i usually buy things from), not an easy task..

I doubt you will find anything compatible and cheaper. They are available from e.g. Mouser and Digikey, aren't they?

Make sure to look not only at the input specs (levels & speed), but also at the differential outputs. You need RSPECL (Reduced Swing Positive Emitter Coupled Logic) outputs to make your scope happy.

[Mechatrommer]

just now trying to find comparator replacement to unobtanium LMH7322 (LMH7324 also not available from the sources i usually buy things from), not an easy task..

I doubt you will find anything compatible and cheaper. They are available from e.g. Mouser and Digikey, aren't they?

i'll try to find cheapest source i can get first, even from aliexpress 8pcs ADCMP576 alone will cost me $69, mouser and digikey will cost much more damage to my place guaranteed. 10pcs LT1715 is $37 though, but not look deeper on suitability. if no cheaper option, or if its not worth the effort to redesign, then i might just get the $75 probe from ebay, but then not sure what ic it is using. no prog delay spec no BW no nothing, so its shady.

Make sure to look not only at the input specs (levels & speed), but also at the differential outputs. You need RSPECL (Reduced Swing Positive Emitter Coupled Logic) outputs to make your scope happy.

not sure about this yet, limited reading resources. but isnt LA input (comparator output) directly connected to DHO FPGA? ie just logic input 0 and 1? as long as within voltage limit range it should be ok, no?

[ebastler]

if no cheaper option, or if its not worth the effort to redesign, then i might just get the $75 probe from ebay, but then not sure what ic it is using. no prog delay spec no BW no nothing, so its shady.

The low-cost probes do not use comparators with an adjustable threshold, but simpler LVDS drivers -- SN65LVDS1DBVR or similar multi-gate parts. You might be able to spot on the ebay photos what has actually been populated.

not sure about this yet, limited reading resources. isnt LA input (comparator output) directly connected to DHO FPGA? ie just logic input 0 and 1? as long as within voltage limit range it should be ok, no?

The FPGA inputs are configured for LVDS (low-voltage differential signaling), and the comparator voltages are chosen such that the RSPECL outputs are compatible with that. You will need differential outputs on the comparator; they could be LVDS instead of RSPECL, I guess.

The LT1715 you mentioned does not have differential outputs, and its output voltage might damage the FPGA's LVDS inputs? LVDS logic levels are only 1.0V and 1.4V; not sure what the FPGA can tolerate as absolute maximum ratings.

[Mechatrommer]

The LT1715 you mentioned does not have differential outputs, and its output voltage might damage the FPGA's LVDS inputs? LVDS logic levels are only 1.0V and 1.4V; not sure what the FPGA can tolerate as absolute maximum ratings.

yes noted with concern, thanks for the info... while working on another section of dho, i got stucked since some parts havent arrived yet so i start doing reading on LA section, and i managed to pop something out of my fw hacked dho804 with help from diagram you provided earlier, without needing to flow solder the 2x DDR3L RAM in, so there's interesting hope. interestingly, sampling rate and memory depth not reduced so bad when this got activated as somebody else reported/portrayed much earlier. only halved and thats not too bad, its normal imho. 625MSps still can debug 300MHz 16ch logic, yes? 

ps: i guess low cost probe for DHO800/900 and discussions should not be posted here right? otherwise police will tantrum? i prefer to call "advisor" because advisor we can ignore, police if we ignore, we will go to jail, or got banned and cannot post in forum anymore. i sometime will become nonsense advisor myself

[ebastler]

while working on another section of dho, i got stucked since some parts havent arrived yet so i start doing reading on LA section, and i managed to pop something out of my fw hacked dho804 with help from diagram you provided earlier, without needing to flow solder the 2x DDR3L RAM in, so there's interesting hope. interestingly, sampling rate and memory depth not reduced so bad when this got activated as somebody else reported/portrayed much earlier. only halved and thats not too bad, its normal imho. 625MSps still can debug 300MHz 16ch logic, yes? 

Be careful when probing around and making connections across the 50-pin connector! There are definitely voltages there which the LVDS inputs won't like, including negative voltages.

The 625 MHz sampling rate for the LA is as expected, and I agree that it is adequate. A bit inconvenient maybe that it's such an odd number. The remaining 625 MHz for a single analog channel, or only 156 MHz when using 3 or 4 analog channels, are the disappointing part. (And the part which is not "normal" -- the analog sampling rate in MSOs is typically limited by the ADC, and does not get reduced when digital channels are activated.)

That AWG board looks promising!   But yes, let's be good boys and move this scope-specific discussion to the DHO800 hacking thread.

[UK]

i guess low cost probe for DHO800/900 and discussions should not be posted here right?

A new thread will be better since many new users come here for the DHO800/900 series. They won’t think to look for information in the MSO5000 threads and may easily miss it.

[Mechatrommer]

Be careful when probing around and making connections across the 50-pin connector! There are definitely voltages there which the LVDS inputs won't like, including negative voltages.

thanks to the diagram you provided. made some probing earlier, i believe whats missing is 4V rail. but i got MPM3630 already in case i need it.

i guess low cost probe for DHO800/900 and discussions should not be posted here right?

A new thread will be better since many new users come here for the DHO800/900 series. They won’t think to look for information in the MSO5000 threads and may easily miss it.

agreed. i'll make another new sub thread when something practical achieved.

[Tarloth]

ps: i guess low cost probe for DHO800/900 and discussions should not be posted here right?

NO, THIS IS THE thread OF THE LOW COST PROBE, your posts are in the wrong place, but some people not understand 

[Mechatrommer]

ps: i guess low cost probe for DHO800/900 and discussions should not be posted here right?

NO, THIS IS THE thread OF THE LOW COST PROBE, your posts are in the wrong place, but some people not understand 

which one of my post is not about low cost probe?

[UK]

I assume he just saw a 'DHO800/900' model name in the thread of the MSO5000 probe.
Hope this dude never gets any sort of gun or police badge in real life. 

I'm a bit nervous when he starts writing in all caps.

[ebastler]

I'm a bit nervous when he starts writing in all caps.

Fortunately this forum software does not offer the functionality to send a proper Howler.

[oliv3r]

Thanks to @sergk for the measurements of the DHO900's LA slot... can say with confidence that it's absolutely the same as on MSO5000.

Almost finished the shell for the mini-HDMI board, but the PCB will definitely require some edits for adding several slots and holes for the screws.
@oliv3r, did you already order the PCBs?

I did not, I've been simmering on a different board, so that I can review it with fresh eyes, and new insights So what changes are you thinking of?

Really hope oliv3r will publish the final version of its board soon and I won’t have to recreate it from scratch.

Yeah, I got distracted a bit; I will certainly publish everything, nothing to be recreated.

I see you added 3 screws, I wonder if there's room for them, and _need_.

Though those 3D renders, so sexy!!

@oliv3r pls, check the board outline in the attachment. PCB requires small edits.

So, this raises a few questions. Do we really need 5 screws? can we do with just one in the 3 (1 in the middle)? They all go through traces :p and in the middle, it's not an issue, I can change the trace, but the outer two traces go between some caps/resistors, rerouting that is a little trickier. I've added a 2.2mm hole (smallest kicad footprint is 2.1 but want to leave room fro the threads?) and it looks like this. Might prefer to get the trace slightly further away from the shield hole though ... shouldn't be an issue?

Also, do we need to cut away so much from the connector side? I don't mind doing it, but the connector itself is much wider then the PCB (see attachment)

You took a thread from this forum that had nothing to do with your discussion and invaded it with impunity even though eblaster warned about it several times.

First of all, I have requested to split off the forum 2 times, but nothing has happened. Others mentioned this as well. If you manage to pull this off, it is much appreciated.

Secondly, The topic is about a low-cost alternative. This is a low-cost alternative. It's just not in easyeda, but that's not a froum crime is it? One of the LAPOD's follows the exact same principle as the original ...

So we are respecting the original thread, we are improving on the original design and adding more LAPOD's 

But again, instead of complaining and derailing the thread about not- LA's, get the forum split. Please. We tried.

Btw

So please, get the topic split! I would very much appreciate if you manage to accomplish this.

what do you think pod_sn65lvds is?


edit: Did the changes already, was easy and doesn't look too bad. Just need to discuss the extra 2 holes :p nvm, got the holes in, not sure about the clearance, but DRC is not complaining ...

[oliv3r]

Great news everyone!

It's been 6 long long weeks, and it's not all there yet, BUT! I've finally gotten my CI/CD pipeline where I want it to be Had to get a few bugs fixed, features added etc to KiBot (Thanks Salvadore!!) but the results are pretty cool.

The repistory is right here, https://gitlab.com/riglol/lapod but only the breakout boards for now. I'm still wrapping up the pods (getting the LCSC part numbers in etc, getting rid of the ERC and DRC errors (or ignoring them where needed). The first pod is nearly done, so I'll hopefully push that tomorrow.

The MR where I'm doing my work is right here https://gitlab.com/riglol/lapod/-/merge_requests/1 and the pipeline has all the outputs https://gitlab.com/riglol/lapod/-/jobs/6004605746/artifacts/browse, such as this nicely blender rendered mugshot! (Should have used that as name instead of `front` ... :p).
There's also a ton of other files there, such as step files, vrml files and what not.

The connector is a bit crooked, that's a bug in blender that'll get fixed in the next big release in march, so until then, that's what it is. Also, I hope that we get a better lightening engine with kibot's blender run soon! There's also the kicad generated render, which looks a little better in some other ways.

Be aware, that the job artifacts expire in a week, which is good, as this is all a little WIP. Once I merge and tag the MR, the artifacts should stay forever of course.

The kicad files are also included as expected it is open source after all.

So ... in case you didn't miss me, I did think of ya'll Now if we could only get Dave to split the thread ...

[S. Petrukhin]

Comrades ebastler and oliv3r, you have filled half the pages of the topic with personal communication with not very related topics. Got carried away.   
This is usually called a flood in forums. 

I do not know how to highlight your communication and move it to a separate topic, is there such a forum opportunity. 
It is possible that a moderator will do this, but not necessarily.

So don't go on, please. Create a new separate topic and put a link to it here so that those interested do not lose the thread of your discussion.

[ebastler]

Comrades ebastler and oliv3r, you have filled half the pages of the topic with personal communication with not very related topics. Got carried away.   
This is usually called a flood in forums. 

I do not know how to highlight your communication and move it to a separate topic, is there such a forum opportunity. 
It is possible that a moderator will do this, but not necessarily.

So don't go on, please. Create a new separate topic and put a link to it here so that those interested do not lose the thread of your discussion.

You might have noticed that

• all our discussion was about a low-cost probe for the MSO5000 (and DHO900), so fully on-topic, and
• oliv3r has asked the admins multiple times to split the discussion about his particular implementation out into a separate thread.

So I can't understand what problem you have with oliv3r and me. And I don't accept your attempts to police us.

[ebastler]

I don't think there is such a thing as a "thread owner".

It's fine with me to have the discussion about oliv3r's design split out into a separate thread; as mentioned, oliv3r has asked for it several times. But starting a fresh thread and losing all the history is not desirable. And I strongly object to the way S. Petrukhin framed his request -- describing this as a personal off-topic discussion by two people, which is wrong on multiple levels.

Anyway, I'm out of here since I will not get a Rigol scope which supports this probe. Nevertheless, I hope oliv3r's design gets finalized, since it is better as well as lower cost than the original Rigol probe.

[S. Petrukhin]

So I can't understand what problem you have with oliv3r and me. And I don't accept your attempts to police us.

I have no desire or ability to control. 

You have created a different product, a different solution and discussing it. Same people have told you about this.
It is a good tone and respectful attitude to the forum users - create a separate topic and post a link to it here.
There are several different options created already and their authors have done just that.
This is my request. 

Moreover, popularity of Rigol 5xxxx is greatly decreasing and growing for 9xxx - topic with 9xxx name will be useful to other users.

[S. Petrukhin]

When you create a new topic with a new solution, a new discussion will appear - I assure you.
And you can post a link to the beginning of the discussion here in the new topic - everything is very simple.

There will be confusion in this topic and it is often unclear for which option the question arose.

[oliv3r]

If more people can spam the admin (dave) that'd be great, I've sent him several messages. Maybe I'll create a new thread, just for dave. I have been reluctant to create a new thread, exactly because I don't want to loose the history. It's to important. Should I have started with a different thread? Maybe. At the time, it was just a remix with different connector between the pods .... Your name is even in the schematic as credits

Also, there was discussion going on in this thread about 'other low cost logic analyzer probes' and this seemed to be 'the home' for alternative probe options.

Anyway, here's the support request thread: https://www.eevblog.com/forum/news/help-in-splitting-topic/new/#new

Creating a new thread and link to the specific post also is painful, as the 'search thread' feature does not work anymore.

Without further ado however, here's the pods I've got them in the pipeline now too. Took some fiddling to fix some erc and drc errors, filed some kicad feature requests, but here are the artifacts https://gitlab.com/riglol/lapod/-/jobs/6025346734/artifacts/browse

What's left to do, is add a nice README of course, and clean up the 'fab' layers. I've 'hidden' them up until now, as they where just annoying. But I'll clean those up too; just because.

The 'component' I've created, will have to be upgraded as well, to deal 'releases' so that the artifacts don't die after a week. Note that this is intentional, as storage costs money, and using storage for 'draft' files is not cool. Also, re-running the pipeline recreates them easily.

Here's the front blender renders of all parts


P.S. Nice to see you back S. Petrukhin

P.P.S. Hopefully UK will pick this up and start doing some amazing 3D cases again :p

[S. Petrukhin]

Your name is even in the schematic as credits

It doesn't matter what my name is. 
I made a primitive construction, it costs nothing.
Anyone can use it at their discretion without contacting me, including for commercial purposes.

I don't understand your tenacity.
Maybe you have little experience and do not yet know the traditions and respectful attitude - I don't know.
But demonstrating this and showing lack of culture is not the best option.

You're just losing the interest of 9xxx series users. They will most likely don't come to this topic.

[oliv3r]

You're just losing the interest of 9xxx series users. They will most likely don't come to this topic.

We still need a 9xxx breakout board, which requires a pinout

You could also change the topic to 'MSO5k & DSO9k projects' and spark interest. OR, rename the project that it is specific only for YOUR design, and then clean out all other off-topic discussions

And I asked the admin to split the thread, multiple times, but I don't want to loose the discussion happening, it's too valueable. My hope is still, to get the admin to split the forum. Just needs some attention from the admin, it's only a button press after all.

[ebastler]

Maybe you have little experience and do not yet know the traditions and respectful attitude - I don't know.
But demonstrating this and showing lack of culture is not the best option.

Come on, man. Oliv3r and I have been around here longer than you. Why would you think you are entitled to teach us about forum traditions and culture?

On a loosely related note: Maybe you should reconsider your choice of forum avatar. I know it's just a picture -- but being lectured by a deranged-looking little guy who is waving his arms at me like an ape does in fact irritate me, and taints the reception of your posts.

[S. Petrukhin]

Come on, man. Oliv3r and I have been around here longer than you. Why would you think you are entitled to teach us about forum traditions and culture?

I'm sorry, I have no desire to talk about nonsense and respond to conclusions about the number of messages. 
Obviously, this is not the only forum where my posts are. It's weird... 

[S. Petrukhin]

We still need a 9xxx breakout board, which requires a pinout

The author of the topic on this forum does not have the ability to delete messages, no additional permissions. 
If there was such an opportunity, I would not delete - it is bad and insulting for users. 

Moderators may not interfere here, providing the maximum possible freedom. 

I would suggest that you, nevertheless, create a new topic and insert a link to the beginning of the discussion in this topic in the first message.
It's a common case of "we moved from here: <message link>". 

[oliv3r]

We could start fighting here, so that dave comes in and splits the thread

BTW, you can edit the subject of the first message in a thread, which is also the thread topic

Or, we can just ignore all the bickering and focus on the part discussion at hand. So feel free to do some reviewing of the schematics/pcb/bom

Once I've got a 'v1.0' and we don't have a split thread, I surely will create a new thread, as the history is less relevant then.

[oliv3r]

I just did a Paper print, just to see how it would fit int he scope. Depending on how much room the case would consume on the sides, the second output is 'close' but not too close. I think there's about a cm between the bnc connector (with the plastic cap on) and the paper edge of the PCB.

As for the HDMi connectors, The cheap ones I got 50 cm with quite fat shrouds around the connector, leave about 1.5mm (bare eye measurement) of space between each connector. I don't really want to get them closer together then that, which means, I won't have more space around the edges either to narrow the footprint. Of course this isn't a problem for the mini-hdmi variant

I'lll leave the DSO7000 and DS1074Z out for the time being, as I don't think we have a verified pinout for either? (Though the DS1074Z might be available already? idk. Doing the pcb design is easy, but I don't have either so ...

I'll let this linger for a bit for people to look at. I've attached the pdf's of the boards, which probably makes for easier review.

Oh, the pipelines are 'done' in that I would be able tag and release the designs and get permanent outputs. I'll merge and tag the results next week, just after the artifacts expire. I won't be sending the gerbers of to the fab just yet, as I need to finish a few other boards too, but I'll start that new thread next week that people are so anxious about :p

Anyways, have a good weekend already

[oliv3r]

Oh, lets do some render pr0n too :p (which I couldn't do in the previous post; 10 attachment limit :S)

[S. Petrukhin]

Congratulations! I have added a link to the separated topics. 

[oliv3r]

I've done a small tweaks to the files, rotated the pods, so they fit better on paper, switched to kibot 1.6.4 for the pipeline, bunch of erc/drc errors I overlooked. Things are looking really good now. I'll merge this to master, and tag the first release candidate so I can get some PCB's ordered.

Hopefully UK comes along again with some cool 3D designs for the housings

I do have to still do a few other PCB's (wanna do one big LCSC order for parts, and need some parts for measurements before ordering PCB's. OTH, they are so cheap, might just order the PCB's anyway ... we'll see.

[S. Petrukhin]

My humble opinion about using HDMI connectors.

They are very bulky and, if you use industrial cables, they are heavy.
As a result, we get a large and solid lever on the adapter in the sight to break and pull it out. It may be accidental.
Perhaps Mini-HDMI is more convenient.

But why use HDMI if LVDS works great on a simple flat cable?
After all, the main idea of the probe is to convert a direct signal for transmission over a well-stable differential pair.

If you wanted to divide the 16 inputs into parts, which is reasonable, then flat cables of smaller width and IDC connectors would be quite practical.

And yet, maybe you didn't notice, but the guys at Rigol didn't care about the equal length of the conductors and even put LVDS terninators on the wrong side in the probe, and not in the scope - they discussed it. But it works. 
The minuscule differences that arise are very far beyond the scope resolution.

You will get a greater impact from the capacity of connecting the probe to the circuit under study.
We have a proverb: the skin is not worth the dressing. No matter how beautiful your shoes are, they will get dirty on a dirty road. 

[oliv3r]

Thanks for your feedback! It is much appreciated :p

My humble opinion about using HDMI connectors.

They are very bulky and, if you use industrial cables, they are heavy.
As a result, we get a large and solid lever on the adapter in the sight to break and pull it out. It may be accidental.
Perhaps Mini-HDMI is more convenient.

Indeed, which is why there is the mini-HDMI variant. But getting mini-hdmi - mini-hdmi cables is probably very expensive/hard to get. I was thinking of even using micro-hdmi, but those connectors are very hard to properly route, due to the pin-pitch, and also don't have through-hole mechnical bits, to keep them in place.

But not sure if I get your thing on 'industrial HDMI connectors'. Why? Nobody is using industrial IDC connectors on any of the pod designs? So 'normal' HDMI cables are not so bulky, are cheap and are shielded. But a simple flatcable is enough! Yes it is. The fact that they are shielded is a bonus, not a requirement. What other common, reusable connectors do we have? The thought of using IDE connectors even crossed my mind :p but 40/80 pins is too much, and who has those still

But why use HDMI if LVDS works great on a simple flat cable?
After all, the main idea of the probe is to convert a direct signal for transmission over a well-stable differential pair.

Sure, but now you have a cable designed for this. isn't HDMI "just LVDS" signal as well? If LVDS is so amazing, why is HDMI shielded? And again, what other convinient connectors do we have? USB-C is an option, but the reversibility is actually at your disadvantage here imo. And lets be fair, the IDC connector is really just butt-ugly But sure, I could have gone with those flat cable 'serial' IDC connectors (x4). But still a bigger pain to deal with for a lot of 'slightly less DYI' people

If you wanted to divide the 16 inputs into parts, which is reasonable, then flat cables of smaller width and IDC connectors would be quite practical.

Yeah but I also don't like the 'robustness' of these flatcables. They are a bit too flappy. I'm sure they'll hold for years of course.

And yet, maybe you didn't notice, but the guys at Rigol didn't care about the equal length of the conductors and even put LVDS terninators on the wrong side in the probe, and not in the scope - they discussed it. But it works. 
The minuscule differences that arise are very far beyond the scope resolution.
[/quote]
I'm fully aware. Also, the traces inside the scope ARE length matched what I saw in the x-rays anyway. So whoever did the probes didn't care, wasn't aware. And indeed, the difference is miniscule. But, if you build something, build it with pride. Doing length-matched traces was a fun excersize. Sure it was frustrating at times. But it's a labor of love after all Might as well polish it a little bit. It's not unheard of to over engineer things and it doesn't cost anything extra.

You will get a greater impact from the capacity of connecting the probe to the circuit under study.
We have a proverb: the skin is not worth the dressing. No matter how beautiful your shoes are, they will get dirty on a dirty road. 

You can keep polishing a turd, but it will never become shiny

Just kidding, we pride ourselves in what we do, do we not?

[S. Petrukhin]

I've never studied HDMI standard, I don't know if it uses LVDS.
But I didn't see any soft cables.
When you receive the finished device, show a photo and share your opinion on how the 4 plugs in the adapter behave.

The IDC with clamps is very reliable and the 6 cores of a flat cable can be very flexible, especially in 500mil step.
You could look at RJ11 as an add-on. But it will take 16 of them...

For training and pride in work, this is an argument. 

[jsobell]

I like the look of the design, although finding some of these components is a real pain!
Quick question, in the SN65LVDS pod, why are EN and /EN both held high at 3.3V?

J.
Edit:

I see why. Your design is for the SN65LVDS391 and not the SN65LVDS047 version.

[jsobell]

Actually, the KiCad part in the schematic is wrong. It should be SN65LVDS391, and not the SN65LVDS047W in the diagram.
The 047W is a 5V part with different pinout.
LCSC don't have any (surprise!) but if you use the SN65LVDS047W then I guess you can do the old -2.2V trick to get over 5V, but you'll also have to fix pin 8, as it won't work if it's high.

Cheers,
 Jason

[oliv3r]

Thanks for looking into this! I think I also see the error of my ways I took the kicad build in symbol for the quad SN65LVDS, because it was much prettier drawn. As you stated, it is a different part!! SN65LVDS047PW which is not what I intended. I wanted it to be the SN65LVDS31D (but have to tripple check that now too) as you rightfully stated! I'll use the ugly symbol from lcsc for the actual part, and draw it prettier instead.

Thank you! This is golden feedback and saved me a lot of agony!

As for parts availability, those TI parts where a problem ever since the component shortages. digikey/mouser should have better availability I've been told. But I prefer to at least put all BOM parts as LCSC parts for now. Don't thin it's useful to use internal part number for each vendor

As for tying both EN and !EN to 3v3, the datsheet has a truth table, where it states that if EN is high, !EN is a 'irrelevant', and I wanted the pin to be a well defined value and not floating. But on second thought, might as well tie it to GND instead.

[oliv3r]

So, https://climbers.net/sbc/clone-pla2216-logic-probe-analyzer/ is where I got the sn65lvds idea from. The only 'problem' is the termination resistors. Which now sit close to the sender, rather then the receiver. But we can't put them near the receiver for obvious reasons.

What's confusing me right now, is that Nikki's pinout of the SN65LVDS doesn't match what's in the datasheet. His pinout is much 'easier' to use, all diff pairs on one side ...
   C354139 is the SN65LVDS391PWR, TSSOP with a nicer pinout. C3239334 is the one I've used, SN65LVDS31D, with the alternating pinout. So .. I'll do it again, this time with the right part

So I've reworked it, but didn't do the whole '2 footprints' solution. A, because it makes routing harder, and B, hopefully the shortage issue is less of a problem.

Besides, doing a SOIC variant of the PCB is always an option.

[oliv3r]

So this is how it looks now with the proper chip

though just spotted my gnd fill not looping around my mounting holes on the left, so gotta check that out now too

[jsobell]

As for tying both EN and !EN to 3v3, the datasheet has a truth table, where it states that if EN is high, !EN is a 'irrelevant', and I wanted the pin to be a well defined value and not floating. But on second thought, might as well tie it to GND instead.

Ah yes, I thought it was an XOR, but it's just an OR gate with an inverter on one leg. Yes, I'd tie it down too, as they do specify that all unused enable lines should be tied to VCC or GND as appropriate.
Have you made one of these yet? I'd be very interested to see one.
My only additional feedback is that I would use a very short ribbon cable to the initial pod, as I don't trust the front not to get knocked or pulled, particularly with four HDMI cables hanging off it.
The 924 model has a constructed socket with the case plastic supporting it, but the 800 self-mutilated models look more fragile as there's no additional plastic supporting the socket soldered to the main board.
Having said that, in my setup the direct plug would probably be more manageable as it's on a VESA mount.

[oliv3r]

As for tying both EN and !EN to 3v3, the datasheet has a truth table, where it states that if EN is high, !EN is a 'irrelevant', and I wanted the pin to be a well defined value and not floating. But on second thought, might as well tie it to GND instead.

Ah yes, I thought it was an XOR, but it's just an OR gate with an inverter on one leg. Yes, I'd tie it down too, as they do specify that all unused enable lines should be tied to VCC or GND as appropriate.

I did change it to tie them better, but also the proper chip only has a single enable pin for channels 1  & 2, and a single pin for 3 & 4. So your observation was sharp and proper, not relevant after using the correct chip

Have you made one of these yet? I'd be very interested to see one.

Me too :p

Not yet, I am in the 'review' process right now, where I'm accumulating feedback (whilst also finishing up some other PCB's so I have one big JLCPCB order to do, because of shipping). WIth hardware, it's better to wait a bit longer and get some valued input, as that of yours. While iterating is of course cheap, Multiple eyes help more of course.

My only additional feedback is that I would use a very short ribbon cable to the initial pod, as I don't trust the front not to get knocked or pulled, particularly with four HDMI cables hanging off it.

That is most certainly a possibility. But I leave that up to the user/builder. It's not like this is a product I'll be shipping. But one could use a male header instead of a female header on the breakout board, and connect it via a ribbon cable. Or just solder a ribbon cable. Or use a female -> male ribbon cable. The options are certainly there. I'm not sure yet on the wait issue, but the scope's female connector should be able to handle the weight quite well imo.

The 924 model has a constructed socket with the case plastic supporting it, but the 800 self-mutilated models look more fragile as there's no additional plastic supporting the socket soldered to the main board.
Having said that, in my setup the direct plug would probably be more manageable as it's on a VESA mount.

I wish my scope had a VESA mount

[jsobell]

Your schematic shows a TLV74325PDBVR regulator, but that's a 2.5V output and the SN65LVDS391PWR requires a minimum of 3V, so I suspect it should be a TLV74333PDBVR.

[jsobell]

Ah, I see you've already patched it in the repo

[Electro Fan]

Have you made one of these yet? I'd be very interested to see one.

Me too :p

LOL

oliv3r you do great work