RE: BUS FAULT - Instruction bus error

Hakon — Sun, 30 May 2021 14:46:54 GMT

[quote user="Learner"]Meanwhile, can you please comment on why after this change in prj.conf the fault disappeared?[/quote]

Compiler optimizations generally reduces the amount of stack required by the application. It's difficult to tell without having looked at your code. It could be a stack overflow in some of the threads, but I'm not 100 % certain.

RE: BUS FAULT - Instruction bus error

Learner — Fri, 21 May 2021 11:51:47 GMT

Hi Hakon,

Thank you for your suggestion. I will need to undo some of the changes that made the MPU/BUS FAULT disappear in order to reproduce the problem. I will let you know how I got on.

I have reproduced the MPU FAULT,

[00:04:46.795,989] <err> os: ***** MPU FAULT *****
[00:04:46.795,989] <err> os: Instruction Access Violation
[00:04:46.796,020] <err> os: r0/a1: 0x00000000 r1/a2: 0x00000000 r2/a3: 0x20002c40
[00:04:46.796,020] <err> os: r3/a4: 0x00000001 r12/ip: 0x200033f4 r14/lr: 0x0001f7d5
[00:04:46.796,020] <err> os: xpsr: 0x81000000
[00:04:46.796,020] <err> os: Faulting instruction address (r15/pc): 0xee19c986
[00:04:46.796,020] <err> os: >>> ZEPHYR FATAL ERROR 0: CPU exception on CPU 0
[00:04:46.796,051] <err> os: Current thread: 0x20002c40 (sysworkq)
[00:04:47.033,508] <err> os: Halting system

the addr2line command gave this response,

C:\WINDOWS\System32>C:\Zypher\v1.5.0-rc1\toolchain\opt\bin\arm-none-eabi-addr2line.exe -e C:\Sandbox\Main-RX-TX\build_nrf52833dk_nrf52833_NO_DEBUG_OPTIMIZATIONS_MPU_FAULT\zephyr\zephyr.elf 0x0001f7d5
C:/Zypher/v1.5.0-rc1/zephyr/drivers/spi/spi_nrfx_spim.c:250

Line 250 corresponds to the return from the function spi_nrfx_transceive()

static int spi_nrfx_transceive(const struct device *dev,
const struct spi_config *spi_cfg,
const struct spi_buf_set *tx_bufs,
const struct spi_buf_set *rx_bufs)
{
return transceive(dev, spi_cfg, tx_bufs, rx_bufs, false, NULL);
} >>> This is line 250

It looks like the fault occurred in the SPI driver function transceive(). However, This function gets called for every SPI transaction. Why is it that it works for seconds, minutes, and sometimes even over an hour then eventually fails with a MPU FAULT?

I will have to debug a bit deeper than I was expecting to come to the bottom of this problem

Meanwhile, can you please comment on why after this change in prj.conf the fault disappeared?

[quote userid="92434" url="~/f/nordic-q-a/75077/bus-fault---instruction-bus-error"]CONFIG_DEBUG_OPTIMIZATIONS=y
CONFIG_COMPILER_OPT=""[/quote]

Hopefully, the reply will be quicker this time.

Thank you.

Kind regards

Mohamed Belaroussi

RE: BUS FAULT - Instruction bus error

Hakon — Fri, 21 May 2021 10:57:05 GMT

Hello,

[quote user=""]<err> os: r3/a4: 0x00000001 r12/ip: 0x2000337c r14/lr: 0x0001ee1d[/quote]

Can you check the address on "lr"? It should work with addr2line and you can also find it in the .map file.