Random hangs on cold boot


I got some random hangs on cold boots of my Unmatched board:

  • The serial port reads “f0???” and the boot process doesn’t continue.
  • The same output always shows each time if I only press the reset button, when it is broken. Only a cold shutdown/boot cycle may change it.
  • It happens about 2/3 the time. The boot is normal otherwise, and resets on the successful boots always work too.

I didn’t find anything about this problem. Any help would be really appreciated!

Maybe you have an issue with your power supply? What kind of power supply are you using? Did you ever try it with a different motherboard? How about your enclosure, what kind of case are you running in (make sure the board is securely mounted and there are no intermittent shorts).

There is a documented issue with the baud rate for the ZSBL which is wrong, it is 89856. This is mentioned in the Software Reference Manual. Some people have reported that the ZSBL messages are legible if they set the baud rate to 56K.

Since you are getting ZSBL messages, that suggests the board is having trouble reading the SDcard. Maybe try reseating the card to see if that helps. Also, check the type of SDcard. There are some SDcards that don’t work in the board. If this isn’t the card that came with the board, you might need to use a different type. There is some discussion of this in the Software Reference Manual also.

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Thank you. Indeed I can get readable messages saying “0x0000000000000006” with 56K baud rate, which means ERROR_CODE_SD_CARD_CMD8 according to the manual, so yes it’s definitely related to the SD card.

It is weird that it works only 1 out of 3 times no matter reseating or not, so doesn’t really look like a seating problem. The card in use is a 32GB Sandisk Ultra A1 card. I’ll try to use a different card then.