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

[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