SW crash on initialization with MCUMGR and UART_ASYNC_API enabled

[Egor Dolgalev]

Hi,

I faced with an initialization issue of combination two features: MCUMGR and UART_ASYNC_API. I get a crash right after the FW starts. It looks like the SW configuration issue

Crash log:

*** Booting nRF Connect SDK v3.0.2-89ba1294ac9b ***
*** Using Zephyr OS v4.0.99-f791c49f492c ***
[00:00:00.259,521] <err> os: ***** USAGE FAULT *****
[00:00:00.259,552] <err> os:   Illegal use of the EPSR
[00:00:00.259,552] <err> os: r0/a1:  0x0000b54c  r1/a2:  0x20001bba  r2/a3:  0x00000080
[00:00:00.259,582] <err> os: r3/a4:  0x00000000 r12/ip:  0x00000000 r14/lr:  0x00003c1b
[00:00:00.259,582] <err> os:  xpsr:  0x20000000
[00:00:00.259,613] <err> os: r4/v1:  0x00000000  r5/v2:  0x0000b510  r6/v3:  0x00000000
[00:00:00.259,613] <err> os: r7/v4:  0x00000000  r8/v5:  0x00000000  r9/v6:  0x00000008
[00:00:00.259,643] <err> os: r10/v7: 0x00000000  r11/v8: 0x00000000    psp:  0x20003b08
[00:00:00.259,643] <err> os: EXC_RETURN: 0xfffffffd
[00:00:00.259,643] <err> os: Faulting instruction address (r15/pc): 0x00000000
[00:00:00.259,704] <err> os: >>> ZEPHYR FATAL ERROR 35: Unknown error on CPU 0
[00:00:00.259,735] <err> os: Current thread: 0x20001130 (unknown)
[00:00:00.477,264] <err> os: Halting system

I attached the simple project that I use to reproduce this issue (just a simple "hello world" example with enabled options in prj.conf)UART_issue.zip

I use SDK 3.0.2 and toolchain 3.0.2 with nRF52840DK board

[Hakon]

I think maybe I know what's wrong. Can you try setting

CONFIG_UART_0_INTERRUPT_DRIVEN=n
CONFIG_UART_0_ASYNC=y

in prj.conf?

[Egor Dolgalev]

Hakon,

It looks like this config options resolve the issue on boot. I don't see the crash, but UART does not work. Let me describe more about it. I use UART0 for logs and it works. Also, I use UART1 for MCUMGR and I want to use it with async API. When I enable options you recommended I don't see that this UART works. No any answer from it. I modified the test project and attached to this post. As I mentioned earlier, I use nRF52840DK board. Also, .config file is inside attached archive.

Please, take a look.

UART_issue_1.zip

[Hakon]

May I ask you how you are testing this and what your setup looks like?

[Egor Dolgalev]

Sure,

I have nRF52840DK board and USB to UART converter. I attached UART lines to the UART1 configured pins. As for the SW I use AuTerm https://github.com/thedjnK/AuTerm/ to simply send Echo command and get response back.

[Hakon]

I noticed you don't have CONFIG_MCUMGR_GRP_OS=y set in your .config file. That could be the reason why it's not working for you.

Other than that, your setup sounds similar to mine, but I use the MCUmgr command line tool instead. I can confirm that this setup works for me now with uart1 set to async.

[Egor Dolgalev]

It sounds strange. I did again my experiments and got the same results. I set CONFIG_MCUMGR_GRP_OS in prj.conf this time (but without this option it answers with error and this is enough for me to understand that UART works). 

I'm attaching archive with two compiled project with difference only in prj.conf. One bad project and one good (they are in the separate folders with all compilation artifacts). Please, pay attention that I modified pins for UART1 in app.overlay (it might has influence but I have doubts). I didn't do anything else except of modifying prj.conf, pristine build and flash. Even AuTerm tool is stay with COM port opened. And all the time I got the same results: with "good" project it works, with "bad" one doesn't.

UARTs_issue.zip