RE: nrf_fstorage_write() triggers HARD FAULT only when called from usage fault handler

danmcb — Mon, 09 May 2022 11:13:52 GMT

I seem to have resolved the issue. I needed to clear the PENDING flag in the handler. Now the handler works correctly.

void UsageFault_Handler(void)
{
  SAVE_DIAGNOSTIC_REGISTERS;
  SCB->SHCSR &= !(SCB_SHCSR_USGFAULTPENDED_Msk);
  project_fatal_error("USAGE FAULT");
}

RE: nrf_fstorage_write() triggers HARD FAULT only when called from usage fault handler

danmcb — Mon, 09 May 2022 09:43:41 GMT

I could trace the hard fault to here:

00029e0e <sd_flash_write>:
   29e0e:   df29         svc   41   ; 0x29
   29e10:   4770         bx   lr
   29e12:   bf00         nop
   29e14:   4618         mov   r0, r3

So the SVC call seems to trigger the fault.

I guess somewhere in the handler I need to do something (enable ints?). Our handler is rather simple. SAVE_DIAGNOSTIC_REGISTERS is just a macro that saves all diag info for later saving/printing.

void UsageFault_Handler(void)
{
  SAVE_DIAGNOSTIC_REGISTERS;
  project_fatal_error("USAGE FAULT");
}