Trying to figure out a bus fault error (Zephyr + NRF52840)

Question

Hey all,

I'm looking for a bit of guidance here to nail a bus fault that happens about 30 minutes into the program.

The message is the following:

[00:32:57.663,177] <err> os: ***** BUS FAULT *****
[00:32:57.663,177] <err> os:   Precise data bus error
[00:32:57.663,208] <err> os:   BFAR Address: 0x80bf68c8
[00:32:57.663,208] <err> os: r0/a1:  0x80bf68b4  r1/a2:  0x20029668  r2/a3:  0x20029640
[00:32:57.663,238] <err> os: r3/a4:  0x00000040 r12/ip:  0x2002158b r14/lr:  0x0004307d
[00:32:57.663,238] <err> os:  xpsr:  0x91000000
[00:32:57.663,238] <err> os: Faulting instruction address (r15/pc): 0x00043d9e
[00:32:57.663,299] <err> os: >>> ZEPHYR FATAL ERROR 25: Unknown error on CPU 0
[00:32:57.663,330] <err> os: Current thread: 0x20002828 (unknown)
[00:32:57.724,395] <err> fatal_error: Resetting system

Reading through previous threads I found some information:

(base) PS \build\zephyr> arm-none-eabi-addr2line.exe -e .\zephyr.elf 0x4307d
C:/ncs/v2.5.0/zephyr/kernel/sched.c:1959
(base) PS \build\zephyr> arm-none-eabi-addr2line.exe -e .\zephyr.elf 0x43d9e
C:/ncs/v2.5.0/zephyr/kernel/pipes.c:217

That tells me that the error seems to be in one of the pipes. Additionally I found the following:

0x20029668:
0x20029640:
 .noinit."../src/tasks/controller.c".0
                0x0000000020028f60      0x800 app/libapp.a(controller.c.obj)
                0x0000000020028f60                _k_thread_stack_controller_rx_task_tid

It seems the receiver task (controller_rx_task_tid) is causing the issue, which makes sense because that thread is related to writing to some pipes. So far I think I'm able to narrow it to where the issue is happening.

What I'm confused about and could not find any information about was:

[00:32:57.663,208] <err> os:   BFAR Address: 0x80bf68c8

Is there a peripheral with that address on the NRF52840 series? I could not find that on the product specification. There are two addresses in that range that I'm not sure where they are:

[00:32:57.663,208] <err> os:   BFAR Address: 0x80bf68c8
[00:32:57.663,208] <err> os: r0/a1:  0x80bf68b4

Any suggestions or additional information you can give me that could help me search for other things is appreciated.

Cheers,

Alberto

Albert_0 · Answer

Hi Vidar, 
 The overflow was on the buffer because the index was getting bigger than it should have. 
 I ran some tests for the last four and a half hours and it all seems to work well. Some issues were also due to some checksum errors, and I added additional checks to prevent accessing buffers out of boundaries. 
 Thanks you very much for the help, I'm happy how this is working now and I think all is solved. 
 Cheers, 
 Alberto

Trying to figure out a bus fault error (Zephyr + NRF52840)

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