Bug in nRF UARTE driver, async Rx buffer handling

RE: Bug in nRF UARTE driver, async Rx buffer handling

Kazi Afroza Sultana — Fri, 07 Nov 2025 09:09:32 GMT

Hello,

we are working on this bug. I will let you know if there is an update.

RE: Bug in nRF UARTE driver, async Rx buffer handling

Tom Weber — Fri, 31 Oct 2025 15:46:20 GMT

Same here. I increased the timeout to 200 us (about 20 bytes) as a workaround.

RE: Bug in nRF UARTE driver, async Rx buffer handling

ahmed-dl — Fri, 31 Oct 2025 11:30:00 GMT

Hi, is there any work towards fixing this bug? We are using high baudrate of 1M without flow control and low timeouts of 100us and see this problem. When increasing the timeout to 1ms we don't see this problem anymore.

RE: Bug in nRF UARTE driver, async Rx buffer handling

ahmed-dl — Fri, 31 Oct 2025 10:42:53 GMT

I'm currently experiencing the same bug when using no HW flow control. I also saw that the problem goes away when using higher timeouts.

Did you find a better workaround or solution for this problem?

RE: Bug in nRF UARTE driver, async Rx buffer handling

Kazi Afroza Sultana — Wed, 24 Sep 2025 12:24:33 GMT

Hello,

It looks like a bug in the driver; the driver intentionally handle the ENDRX first before UART_RX_BUF_REQUEST (RXSTARTED event) for other reasons. In case of short buffer that event order may happen and that is unexpected. I think you have used high baud rate?

RE: Bug in nRF UARTE driver, async Rx buffer handling

Tom Weber — Mon, 15 Sep 2025 11:02:02 GMT

What baud rate and Rx timeout are you using?

My workaround for now is to use a longer timeout, it means the bug will not get triggered.

RE: Bug in nRF UARTE driver, async Rx buffer handling

helpfulchicken — Sat, 13 Sep 2025 22:59:15 GMT

I had a similar issue (I think, I may be wrong in my understanding of your issue) where using the asynchronous UART driver I would get missed and corrupted bytes received.

I stumbled on a solution to my issue in some sample code.

While using async UART API:

CONFIG_UART_ASYNC_API=y
CONFIG_UART_INTERRUPT_DRIVEN=n

I would see corrupted and missed Rx bytes intermittently.

I found that the issue went away if I added the following:

CONFIG_UART_0_ASYNC=y
CONFIG_UART_0_INTERRUPT_DRIVEN=n
CONFIG_UART_0_NRF_HW_ASYNC=y
CONFIG_UART_0_NRF_HW_ASYNC_TIMER=2
CONFIG_NRFX_TIMER2=y

CONFIG_UART_1_ASYNC=y
CONFIG_UART_1_INTERRUPT_DRIVEN=n
CONFIG_UART_1_NRF_HW_ASYNC=y
CONFIG_UART_1_NRF_HW_ASYNC_TIMER=3
CONFIG_NRFX_TIMER3=y

In my use case, I am using both uart0 and uart1.

RE: Bug in nRF UARTE driver, async Rx buffer handling

Kazi Afroza Sultana — Mon, 25 Aug 2025 14:11:01 GMT

Hello,

The UARTE peripheral on Dks is known to have limitations in signaling partial buffer fills. I am not aware if we have some woraround for nRF54L15.

I have asked team. I will come back to you later.

Thanks.

Kazi