Did something ***, now no flash memory.

brohr01 · ‎2025-01-26

I was trying to change an option byte from the embedded bootloader of an stm32u5 over canFD. Long story short I sent it some messages that were not formatted correctly and It looks like I have bricked the chip. Trying to connect in stm32cubeprog with my st-link over swd I get
Error: ST-LINK error (DEV_TARGET_HELD_UNDER_RESET)

I have measured voltage on the reset line and it is 0.0v, I tried to pull it high through a 10k resistor and I still get the same error. The most interesting part of this is when I ran "st-flash reset" I get the following output

st-flash 1.8.0
2025-01-26T20:22:12 INFO common.c: STM32U5Fx_U5Gx: 3026 KiB SRAM, 0 KiB flash in at least 8 KiB pages.
Failed to reset device

Notice the 0 KiB of flash, but it still identifies the chip and sram. Any other ideas to try before I desolder and replace the chip?

Uwe Bonnes · ‎2025-01-27

Does the target get hot and suck substantial more current? Then high voltage on some pin killed your chip.

Andrew Neil · ‎2025-01-27

@brohr01 wrote:
I have measured voltage on the reset line and it is 0.0v, I tried to pull it high through a 10k resistor

So did the pullup actually change the voltage at the pin?