Hi, I have an STM32 processor board, and I’ve tried it with the ATP Carrier board, where the boot and reset buttons work fine.
On the my Main (dual function) carrier board, however, I am unable to enter bootloader mode. I looked closely, and it doesn’t seem that pin 11 of the processor socket has a trace going to it from the boot button!?!? Is there a design problem?
https://learn.sparkfun.com/tutorials/mi … okup-guide mentions
"Reset and Boot Buttons
Each board includes a reset and boot button. There is an additional reset button PTH next to the reset button. Hitting the reset button to restart your Processor Board. Hitting the boot button will put the Processor Board into a special boot mode. Depending on the processor board, this boot pin may not be connected."
So…a bit of both? I can’t really attest to the reasoning behind our design implementations, but if you’d like more info you can file an ‘issue’ here https://github.com/sparkfun/SparkFun_Mi … ble/issues and an engineer should become aware of your query 
Thanks for the reply! I read that as meaning the boot signal on the processor connector might not be used (and thus connected) to the processor, not that the button itself might not be connected to the connector – that would not be processor specific. I will report this as a bug.
Hi Tony,
Your post caught my attention because I’m dealing with a different issue on the mainboard double. In my issue, it seems like my mainboard is damaging the STM32 MCU boards.
However, I do have a second mainboard double and can confirm that a STM32 MCU micromod board can enter boot loader mode by invoking the pattern with the buttons - hold boot, press reset, and then release boot.
The reason this caught my attention is that in my case, once a MCU has been removed and placed in a known working carrier board, it will no longer enumerate the USB boot loader.
You may want to confirm it still works with your ATP carrier board.