Enabling UART0 Async while Shell over USB is enabled caused system crash

[cgi27]

Hi there, 

I am trying to use shell with the USB and logging with RTT. Additionally, UART0 async is used to communicate with sensors. Here a snapshot of the proj,config:

# Config shell and log
CONFIG_RTT_CONSOLE=y
CONFIG_SHELL_BT_NUS=y
CONFIG_SHELL_BACKEND_RTT=n
CONFIG_SHELL_BACKEND_SERIAL=y
CONFIG_SHELL_LOG_BACKEND=n
CONFIG_LOG_BACKEND_UART=n
CONFIG_LOG_BACKEND_RTT=y

# Configure bluetooth
CONFIG_BT=y
CONFIG_BT_PERIPHERAL=y      
CONFIG_BT_DEVICE_NAME="Shell-BT-NUS"

# Enable the NUS service
CONFIG_BT_NUS=y
CONFIG_SHELL_START_OBSCURED=n

# Configure USB
CONFIG_USB_DEVICE_STACK=y
CONFIG_USB_DEVICE_PRODUCT="Zephyr USB"
CONFIG_USB_DEVICE_PID=0x0004
CONFIG_USB_DEVICE_VID=0x0001
CONFIG_USB_DEVICE_INITIALIZE_AT_BOOT=n
CONFIG_USB_COMPOSITE_DEVICE=y
CONFIG_USB_CDC_ACM=y
CONFIG_USB_DRIVER_LOG_LEVEL_ERR=n
CONFIG_UART_INTERRUPT_DRIVEN=y

# Enable UART0 Async
CONFIG_UART_ASYNC_API=y
CONFIG_UART_0_INTERRUPT_DRIVEN=n
CONFIG_UART_LINE_CTRL=y
CONFIG_UART_0_ASYNC=y
CONFIG_UART_USE_RUNTIME_CONFIGURE=y

I am getting these message errors on the RTT logging:

[00:00:00.000,640] <err> os: ***** USAGE FAULT *****
[00:00:00.000,640] <err> os: Illegal use of the EPSR
[00:00:00.000,640] <err> os: r0/a1: 0x0002c168 r1/a2: 0x2000ca87 r2/a3: 0x00000010
[00:00:00.000,671] <err> os: r3/a4: 0x00002710 r12/ip: 0x00000001 r14/lr: 0x00013b8b
[00:00:00.000,671] <err> os: xpsr: 0x60000000
[00:00:00.000,671] <err> os: Faulting instruction address (r15/pc): 0x00000000
[00:00:00.000,732] <err> os: >>> ZEPHYR FATAL ERROR 35: Unknown error on CPU 0
[00:00:00.000,762] <err> os: Current thread: 0x200032a8 (main)
[00:00:00.195,526] <err> fatal_error: Resetting system

This issue does not happen when I commented out all the lines beyond # Enable UART0 Async. Am I missing something here? 

[Charlie]

Hi,

Did you manage to make your device work as USB CDC Shell/console without error first?

You can refer to a previous discussion:(+) use NrfConnect SDK with 52840 dongle USB CDC Shell/console - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com).

Best regards,

Charlie

[cgi27]

Yes with lines 30 onwards being commented out

[Charlie]

Could you check your final configuraiton with CONFIG_UART_INTERRUPT_DRIVEN?"CONFIG_UART_INTERRUPT_DRIVEN must be set for CDC ACM driver" according to the source codes: sdk-zephyr/subsys/usb/device/class/cdc_acm.c at main · nrfconnect/sdk-zephyr (github.com).

I found the following discussion with a similar usage, it seems no mature solution now.

 (+) Cannot get Async UART0 to work with USB CDC - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

[cgi27]

Yes it's being enabled. I don't have any issue running CDC ACM along with UART0 Async. The problem is when I start using the shell. RTT seems to be working when I set CONFIG_SHELL_BACKEND_SERIAL=n but receive crash log as posted earlier when CONFIG_SHELL_BACKEND_SERIAL=y

[cgi27]

I managed to resolve the problem by adding 

CONFIG_SHELL_BACKEND_SERIAL_API_INTERRUPT_DRIVEN=y