I’m sure this is in the source, readmes, community and/or issues on Github somewhere, but it’s all in bits and pieces.
I’ve got a Photon that I bricked doing local dev a while ago. It won’t do factory reset or safe mode. I can’t put it into DFU mode. The RGB led doesn’t light up at all at any stage.
Although I have considered that it’s just a bad LED or something else wrong with the board, due to the circumstances around it’s demise, I’m pretty sure it’s the flash. I was doing a test loop where I would reset it to factory firmware using DFU (and a little bit of st-flash with a programmer shield), run some tests and reset it back to factory firmware. On one of the runs, DFU hung and I
^C'd the terminal. After that, it wouldn’t do anything anymore. I’m assuming that the firmware got corrupted and won’t boot – even in the bootloader.
This Photon probably only went through the loop < 20 times, so I’d be surprised if it was flash wear.
At any rate, I’d like to try to rehabilitate this little Photon and be able to use it as well as learn something new about hardware. (Also document it for posterity here in the community).
I’ve got the (monolithic) factory firmware, as well as an
unlocker.bin firmware to unlock the bootloader. I’ve got a new Programmer Shield (and openocd installed), an old Programmer Shield with an ST-Link programmer (and a Mac – although I could install Windows on a Bootcamp partition if necessary).
What I’m lacking is a thorough enough understanding of the behavior of a bricked STM32 chip and the programmer(s) to unlock the flash memory and write new firmware w/o having the ability to put our friend into DFU mode.
Anyone out there wanna take a stab?