Our problem is that VDD_RTC has never outputted power on our custom board, and we don’t know why.
I asked the question about the USB Lane Mapping because I was trying to figure out how the link you provided was relevant to our VDD_RTC question.
We had an issue earlier where USB 3.0 was not outputting power on our custom board. To fix this, we had to patch the DTS like the link you gave in post #2. While trying to troubleshoot our VDD_RTC power issue, we thought that the solution might be similar to the USB 3.0 power issue.
To give you more information about our custom board, I included that we’re using lane mapping configuration #2, the CHARGER_PRESENTn pin is grounded for auto power-on, and we are using L4T version 28.1. Also, our custom carrier board does not have the ‘Carrier Board Config’ EEPROM chip (designator U11 on P2597).
I don’t know if the USB 3.0 power issue (that we already resolved) or any of the information above is relevant to the VDD_RTC issue. I was just trying to provide enough context.
So, with or without all the above information, our issue is this:
We observe VDD_RTC charging the capacitor when the Jetson is on the Developer Kit Carrier Board (P2597), but when we power everything down, move the Jetson to our custom carrier board, and power everything back on, we do not observe VDD_RTC charging the capacitor. The capacitors on the custom board and developer kit board are the same.