I made a mistake a few days ago that resulted in my program erasing part of itself.
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I'm doing a bare metal bootloader on a STM32F407VE and have run into some weird behaviour after erasing sector 4.
Here's the loop I use to do the erasing:
#define APP_first_sector 2
#define LAST_SECTOR 7
HAL_FLASH_Unlock();
for (uint32_t i = APP_first_sector; i <= LAST_SECTOR; i++) {
print("Erasing sector: %d\n",(uint16_t)i);
FLASH_Erase_Sector(i, VOLTAGE_RANGE_3);
print("finished sector: %d\n",(uint16_t)i);
}
HAL_FLASH_Lock();
All print statements executed after erasing sector 4 hang. The hang is in the processing of the VA_ARGS list. It never completes.
I can get around this by adding a '\0' to all print statements executed after the erase sector command. This explicitly adds the terminating code to the va_args list but gives compile warnings.
print("Erasing sector: %d\n\0",(uint16_t)i);
I've done a lot of variations on the loop and the only time there are problems is immediately after erasing sector 4. I can erase sectors 2,3,5, 6 or 7 without issues.
I'm using Ozone to debug the program. I don't see anything unusual/different in the FLASH ACR or status registers after the sector erases.
I've thrown a lot of things into and around the loop to see if anything helps. Here's some of the things I've unsucessfully tried:
- diabled IRQs before and enabled IRQs after
- delays of up to 60 seconds before and after the erase
- moving the lock/unlock into and out of the loop
- removing the print statements from the loop
- disable/flush all the advanced FLASH features before the erase and then flush/restore them after
The weirdest thing is this failing mode is only cleared when I use Ozone to rewrite the bootloader image. Pressing the reset button, issuing a reset via Ozone and even removing power from the board doesn't fix this. A diff of the FLASH when in the failing mode and after a new download didn't show any problems/differences.
I'm confused.
Edited by moderation team to adhere to community guidelines.
