Zephyr UART_ASYNC_API not recovering from UART_RX_STOPPED event

[newUser]

When turning off the UART device, the UART ASYNC API callback will be called with the UART_RX_STOPPED event.

This will then not recover, and the event will be spammed infinitely.

I have tried immediately re-enabling the UART, and disabling the UART. Both do not solve the problem.

What is the appropriate way to handle the UART_RX_STOPPED event?

[Simon]

Could you upload a zipped sample which I can run to reproduce this issue? Please mention the NCS tag used for the sample

Best regards,

Simon

[newUser]

Hi Simon, thank you for your response.

I'm using NCS v1.4.0 (and it also happens with v1.3.1). The issue is occurring when we turn off our 3rd party LTE-M modem, so reproducing it on your side might be quite hard.

I'm mainly curious about how to handle this graciously.

[Simon]

The event UART_RX_STOPPED is generated when an error with the UART happens (see the error_isr() function in uart_nrfx_uarte.c). Read about the different Error conditions on the infocenter and check out the ERRORSRC register as well.

I guess you are getting a framing error and/or a break error, due to a floating rx pin when turning off the 3rd party LTE-M modem. Could you confirm this by reading the value of evt->data.rx_stop.reason in your uart callback function?

Instead of handling this in the software, you should probably go to the core of the issue, and solve that. Check out this case for how to solve this.

Best regards,

Simon