I posed this question about a year ago about a custom carrier for the ZU11EG SOM and didn't really get what we needed. After spinning the board, we found out a few things we HAD to have:
- USBc-UART - without this, we're completely blind as to what is happening on an attempted boot
- PowerGood from the Carrier (or at least the 3-pin headers that allow you to bypass that check)
- Voltage monitoring to match the levels on the carrier – health and safety checks we didn’t know about
- Boot switches/LEDs to match what is on the ADI carrier
A few other things, but that is the gist of what I'm looking to find out. At this point, we can't boot the SOM when mounted to the custom carrier and I want to make sure there are no fundamental issues that I may be missing. On our current board, the footprint for the USBc-UART level shifter was wrong and I haven't been able to successfully rework the board to get that function working. As such, we have no visibility into what errors may be preventing the SOM from properly booting.
With that said, we're about to spin the board again to fix some known issues, but I wanted to ask this again. Is there any list of Carrier-related health and safety checks that are performed during the boot sequence? Ideally, I'd like to know if there are any hardware checks where the hardware is absolutely required. Secondarily, if there are any checks that are "nice to have", but can be removed from the firmware, that would be nice to know, as well.