I am not sure where to ask this, so here it goes:

I was soldering my new Cantor split keyboard, which is using two STM32F401 Blackpill microcontrollers. I had to resolder some parts on the left side, so the soldering there is sloppy. Now when I plug in this side, the board seems to be in flashing/Boodloader-mode instantly without me having to press the BOOT0+NRST botton combo. This causes the left side being unable to “type” because it’s expecting software.

What pins (or switches?) should I take a look at? What could cause the Blackpill to be in Bootloader mode all the time? I tried to read the Documentation of the board, but I’m afraid all of it went right over my head…

Thanks in advance!

  • eceforge@iusearchlinux.fyi
    5·
    8 months ago

    I know it may seem obvious, but did you check the pins of the BOOT0 switch itself and the nearby capacitor? A stray bit of solder there could cause the switch to appear always held down by shorting either the cap or the switch. It doesn’t appear that the boot0 line goes anywhere other than there and the main microcontroller so the issue is likely there.