One difficulty with the bring up of that IO board years ago was missing resistors that led to electrical overshoot on one set of signals. The prototype worked only because the wirewrap was lucky. The first ten boards were not lucky but could be fixed by cutting traces and then soldering resistors in one by one.They don't have your odd pinout where the pairs are split and mixed up.Since there are breakout boards for PCIe with header pins that work, I think there will be no problem to use them on this board.It isn't that simple for high speed signals. The grounds between the pairs are important. Same with length matching and using the correct impedance. Not doing it may work in a pinch but expect strange compatibility issues.For ground yes there are only 2 pins for PCIe GND and the PCIe 1x has 8 lines for GND however they all connect to the same GND so it really does not make sense to add more GND pins.It is your board so your choice. I like the Eurocard modules idea. Good luck with your project.I will test the board in its current configuration, if the PCIe PINS cause problems I will switch to mini PCIe or to the pi 5 connector.
I think it's even more important to match the track lengths and grounds for the SerDes style interfaces as there is no way to fix that later. Using the same PCIe connector as the Pi 5 sounds like a great idea. An m.2 connector is the obvious alternative.
Statistics: Posted by ejolson — Wed Jan 17, 2024 7:22 am