05-05-2018, 02:45 AM
(05-04-2018, 05:42 PM)pfeerick Wrote:(05-04-2018, 02:48 PM)Rocklobster Wrote: Sounds suspiciously like a short in the actual connector going to the GPIO pins. If you haven't connected the other end to a breadboard all you doing is extending the actual GPIO pins so any reading should be the same with or without the ribbon cable connector at the Rock64 board. Try a different cable just to rule it out.
Have you tested voltages at the GPIO pins with and without the ribbon cable attached.
I'm getting the same results on my setup. https://pastebin.com/JXg8mCc4 The only (!!) difference is I plugged in the adapter plate to the ribbon as I needed to be able to disable the SPI Flash as there is a bug in the uboot currently loaded on it.
I think it can only be one of three things... something connected/shorted on the adapter board, something going on in the ribbon, or it could perhaps be adding noise or capacitance or something to the lines used for the SD card, as the pins 32.32,35,36,37,38,40 on the 40 pin Pi-2 bus are shared with the SD card. I'm inclined to think the latter, as there is nothing visibly wrong with the adapter or ribbon.
just to update tests:
Double checked the cable connected to the adaptor and the impedence between contacts is about Mohms
Verified voltage on Rock64 PI-2 contact with nothing connected and later voltage on adaptor edges connected to Rock64 only: no changes
now a question: may using eMMC solve this avoiding noise on contacts pfeerick mentioned?
Thanks all!!
