Async UART timeout calling UART_RX_DISABLED

[Mike Austin (LPI)]

This is my environment

• IDE: VSC
• SDK: NCS v2.2.0
• nRF52832 on custom hardware

I am running the Aysnc UART to receive commands from an external PC.  I want the UART to remain active for at least 60 seconds after the last UART_RX_RDY has been received, but I'm having issues getting this to work as I would expect.

I've got a timer to take care of putting my device into idle mode if nothing is received for a period of 60 seconds, but the UART seems to be receiving a UART_RX_DISABLED event before this time, which means if the user attempts to send any more commands, then nothing happens.

I've set up the async uart as follows:

uart_rx_enable(uart, uart_double_buffer[0], UART_BUF_SIZE, UART_RX_TIMEOUT_MS);

Currently, UART_RX_TIMEOUT_MS (and I'm using v2.2.0 of NCS, so I think the number that is being passed is actually a usec value) is set to 1000.  And what I am seeing is that it is taking ~ 20sec of inactivity on the UART RX before the UART_RX_DISABLED is called.  This then disables the UART and I can no longer send any commands.

I read in one ticket that you can set the UART up using SYS_FOREVER_US for the timeout parameter, and the UART should not timeout.  But when I use this, the UART RX function seems to stop working altogether.

Basically, what I want is for the UART to sit there in the background waiting for commands whilst the device is active.  Then, when my idle timer expires and I put the device into low power idle mode, I will deactivate the UART myself.  Is there another way of doing this rather than trying to use the timeout parameter in the uart_rx_enable() API?

Regards,

Mike

[ovrebekk]

Hi Mike

The UART_RX_DISABLED event shouldn't occur unless you are disabling the RX somewhere in the application. Are you following some of the samples, which disable the RX after every received message? 

Best regards
Torbjørn

[Mike Austin (LPI)]

Hi Torbjørn,

Thanks for the feedback.  I fixed the issue - turns out it was related to me not handling a semaphore correctly, and I think my code was heading off into unknown territory and this was disabling the UART.

Also did a bit of research on the async UART settings and realised that the RX_TIMEOUT parameter has nothing to do with the operation of the UART timing out, but is basically how long things will wait with no activity on the RX before the UART_RX_RDY event is triggered.

Thanks and regards,

Mike

[ovrebekk]

Hi Mike

Good to hear you found the issue. 

Your understanding of the timeout is correct. This simply allows you to ensure that you get RX_RDY before the buffers are full, in cases where there might be a long delay between transactions and data needs to be processed asynchronously. 

Best regards
Torbjørn