We made the board with the open source of Pocket Beagle(https://github.com/beagleboard/pocketbeagle).
We made a total of five.
Only one of them works, and four do not.
I don’t know the cause.
All pin maps have the same voltage.
The voltage of EMU0 (CDN of SD card connector) is 3.3V for normal board and 0V for abnormal board.
How to solve it?
What do we need to check?
You mean you designed and fabbed your own board? Check out the serial console output for SERIAL1. If you’re getting an unending series of CCCCCC… then you’re good. In that case you need to make your own image with a custom uboot to recognize the device. Or you can program the EEPROM. For me it was easier to make a custom uboot since I made thousands.
Octavo has a nice description of how to do this as an app note on their website.
Hope that helps!
Did you check all accessible voltage rails and clocks?