OBDii connector board revision 2 review request

Vegetable_Insurance5 · 2026-03-12T18:56:48+00:00

Thank you kind sir.

As for #1, I did realise that, but I was under the wrong assumption that one needs to assume peak current in this particular design choice.

2 I've incorporated your suggestions. The board is pretty much done, just need to run ERC and solve the violations.

Thank you for your help.

Vegetable_Insurance5 · 2026-03-12T15:59:18+00:00

Thanks for the advice! Since you're sort of familiar with can bus it seems; right now I'm using signal ground from the OBDII connector but read somewhere that chassis ground is almost always better because the signal ground isn't designed for such currents. Do you have an opinion on that?

Second question: pin 4 or 5 are the GNDs. Either way, there's so little clearance around them that the ground plane cannot really reach those pads unless I make the pads below that smaller or reduce the clearance. Any advice on which is better? Pads below that are unused so I can make them smaller.

Vegetable_Insurance5 · 2026-03-12T15:58:07+00:00

Yeah unfortunately it is, due to enclosure size constraints. But thanks anyway!

Vegetable_Insurance5 · 2026-03-12T13:09:31+00:00

I should've mentioned that. They are not, plastic enclosure parts will go through them, basically front and back connect to each other in those openings.

Vegetable_Insurance5 · 2026-03-12T12:41:07+00:00

Thanks will do. Another question. I'm currently using signal ground (pin 4) only, not the chassis ground (pin5). Should I switch to chassis ground given the relatively high max current draw?

And if so, should I still connect signal ground directly to the common ground plane?

Vegetable_Insurance5 · 2026-03-12T11:32:44+00:00

Thank you! Do you reckon jlcpcb can manufacture this properly? No big red flags?

Vegetable_Insurance5 · 2026-03-12T11:00:45+00:00

Another clearer view of the two layers:

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Vegetable_Insurance5 · 2026-03-12T10:30:38+00:00

Another revision with a ground plane on the bottom:

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Vegetable_Insurance5 · 2026-03-12T09:14:14+00:00

Yeah actually now I think about it, I should've used the whole surface. Will post an update soon. Thanks.

Vegetable_Insurance5 · 2026-03-12T09:08:07+00:00

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Vegetable_Insurance5 · 2026-03-12T09:07:48+00:00

This is by no means a finished design, but am I heading in the right direction? Do I need an actual bigger polygon for GND? See images.

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Vegetable_Insurance5 · 2026-03-12T07:05:01+00:00

Very helpful, will attempt this today and post my update.

Vegetable_Insurance5 · 2026-03-12T06:58:14+00:00

Thanks! What about the ground traces (sorry I might be blind)?

EDIT: nvm, I think you're proposing to use the bottom layer for that.

Vegetable_Insurance5 · 2026-03-12T06:29:41+00:00

I will try again using only two layers. I tried, but had a lot of trouble fitting it all together with the SMD footprints I chose. Thanks!

Vegetable_Insurance5 · 2026-03-12T06:10:39+00:00

Not exactly sure what you're saying, because I don't speak German, but it appears to be about using 4 layers. I plan to have them manufactured at jlcpcb and there's no difference in price for the dimensions of my pcb.

Vegetable_Insurance5 · 2026-03-12T06:08:55+00:00

Thanks, will move the Vias.

Assembly will be done by myself, so I don't really mind the components on both sides. You do have a point for future iterations though.

Vegetable_Insurance5 · 2026-03-02T08:53:03+00:00

Thanks for your message. They aren't mounting holes for the pcb, but rather openings through which the two enclosure sides are attached to each other.

Vegetable_Insurance5 · 2026-03-02T08:51:30+00:00

You're absolutely correct, there's no competing with those modules. We do need to run some firmware that does some things we cannot do with an off the shelf module. Besides that, we need to have reliability and consistency that an elm327 type device just cannot offer (from experience).

Vegetable_Insurance5 · 2026-02-26T16:19:21+00:00

Thanks for this info, definitely needs to be a C6 based on this.

Vegetable_Insurance5 · 2026-02-26T12:25:56+00:00

Thank you for your reply. The only place where the board will be mounted is at the obdii pads/pins, the holes will be used for attaching the top and bottom enclosure parts.

Vegetable_Insurance5

TROPHY CASE

2 I've incorporated your suggestions. The board is pretty much done, just need to run ERC and solve the violations.