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

[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