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

[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