nRF52: How to recover from UART BREAK condition

[Jacob]

Hello,

I'm having a system consisting of an nRF52 and another processor, with UART between them. If the other processor restarts, nRF's RX line will be pulled low for some time, triggering FRAMING and BREAK errors, which is somewhat expected.

However, the only way I've figured out to recover from this (get RX to work again) is to restart the entire UART (nrf_uart_disable, nrf_uart_enable). Is this expected?

I'm running Zephyr 2.2, but that shouldn't matter that much in this case. I'm using UART, not UARTE.

Thanks, Jacob

[Simon]

Would it be possible to add a pull-up resistor to the GPIO set as RXD as explained in this ticket?

Best regards,

Simon

[Jacob]

Hi,

Well, that still doesn't solve the issue really. Is it really reasonable that the UART malfunctions in this manner when a BREAK is encountered?

Thanks, Jacob

[Simon]

I'm trying to dig into your problem, but I'm not able to reproduce your issue. I tried to communicate through UART between an nRF9160 and an nRF52840 with flow control enabled. I set the UART RX line of the nRF5280 to GND on the nRF9160, but didn't need to restart the nRF52840 to continue the communication.

Could you upload your nRF52 sample? Or you could check out the samples I have attached and see if you are able to recreate the error/modify it to recreate the error.

UART.zip

Best regards,

Simon

[Jacob]

Hi,

Thanks for looking into this. A colleague of mine has taken over this thing, and it may be caused by another issue (for which a disable/enable procedure happened to help for). He has created another thread here regarding that issue, but I'm unable to find it (the devzone really isn't easy to navigate!).

For now, I think this thread can be closed.

Thanks, Jacob