Random NRF52840 (A silicon) failures

[bkdrock]

Every once in a while I will get a failure that results in the app_error_fault_hanlder() being called and the following info:

ID = 1

PC = 0x14550

error_code = 0x495

line_num = 0x400.

I used the nrf_strerror_get() to try to figure out, but it just returns "Unknown error code".

It happens infrequently, maybe a couple of times per day. Can you provide some info on this error?

[Sigurd]

Hi,

When app_error_fault_handler is called with ID=1, then this is a SoftDevice assertion(NRF_FAULT_ID_SD_ASSERT). But normally the info field should have been 0, i.e. no error_code, line_num or p_file_name should be present.

What SoftDevice version are you using?

[bkdrock]

I am using s140_nrf52840_6.0.0-6.alpha_softdevice.

[Sigurd]

Ok, I will look into the program counter of the instruction that triggered the fault. 

Is the PC value always 0x14550 when the failure happens? or is it a new PC value each time?

[bkdrock]

Yes, I have hit it multiple times, and that has been the value. 

[Sigurd]

Was the error_code and line_num also always the same? What about p_file_name?

Was the compiler optimization set to 0 when you tested this? If not, could you try to reproduce the issue with optimization set to 0 ? and with the Preprocessor symbol DEBUG defined.

EDIT: The instruction that caused the assert in the SoftDevice have been found. I will look into possible reasons for why this is happening, and get back to you.

[bkdrock]

OK, I set the optimization to 0. When I hit the breakpoint this time (in app_error_save_and_stop()) I get:

ID=1

PC=0x14550

but

info=0

So the line_num and p_file_name, which are derived from info, are not valid.