I have some questions regarding the documentation:
J3A2, p.26 of the schematic - pin 3 is marked with a ‘square’ vs. pin 1. I was wondering why that does not follow convention.
Regarding the Solidworks model - the two connectors appear to be 2 50-pin connectors vs. 1 50-pin and 1 75-pin. I assume that is just a mistake in the model, and that the schematic ‘trumps’ the model. The BOM appears to have the correct part # for both.
As far as the spacing between J3A1 and J3A2, is it equidistant at 2mm?
and a comment -
with the connector arrangement as is - making a mate is a bit of an issue since there is no ‘standard’ connector from Samtec that mates with a 5x25 grid. One way of doing it is to use two TMM-125-01-T-D connectors with one TMM-125-01-T-S. Just wondering what the intended interface connector is/was if the above is correct - meaning the latest posted PDF schematic is correct.
The JetsonTK1_ModuleSpecification_PM375_V1.01.pdf shows J3A2 and J3A1 both as 2 mm pitch. I can’t swear that J3A1 and J3A2 could use a single large connector, but it is extremely likely (if you could find such a connector…which would be 25 pins X 5 rows).
I don’t see anything “square” on the actual board or connector, but only the board bottom is visible with the connector installed. The silkscreen on top is very likely your best source of finding pin 1. If you’re brave (and ESD careful) you could measure the voltage on the silkscreen marked pin (which should be pin 1), which should be +5V if it really is pin 1 (as marked on the schematic). The power connector should provide a ground for the test.
The JTAG connector next to it is standard 0.1" pitch (docs show as 100 mil), and 0.1" is 2.54 mm. The JTAG should appear barely larger pitch than the other connector next to it…calling J3A2 2mm pitch looks correct as far as I can tell.
There may be a case of the connector being viewed from top or bottom being reversed in the documentation. I used the silkscreen marked pin 1 (+5V) and pin 73 (ground), and verified +5V and ground pin. So…my board has no visible square, but silkscreen is correct.