Serial UARTE Rx fails with continuous timeout error

RE: Serial UARTE Rx fails with continuous timeout error

Susheel Nuguru — Thu, 03 Jun 2021 07:56:59 GMT

If your application needs a high precision clock (better than internal RC oscillator) Then you need to have XTAL HFCLK on your PCB connected to nRF which can be started using the clock module using the API nrf_drv_clock_hfclk_request. If you have this enabled on both peer and your device, there is better accuracy of the clocks on UART and hence less probability of of clocks jittering causing framing errors.

RE: Serial UARTE Rx fails with continuous timeout error

Manjunath S — Tue, 01 Jun 2021 11:07:28 GMT

[quote userid="6207" url="~/f/nordic-q-a/74854/serial-uarte-rx-fails-with-continuous-timeout-error/311264#311264"]HFCLK [/quote]

Hi,

We are using the internal clock for this communication. and the baud rates are set as per the code above.

I am using nrf_serial_write() and nrf_serial_read() functions to write and read. I am not aware of the HFCLK you are mentioning. Could you please let me know where it needs to be set/configured?

RE: Serial UARTE Rx fails with continuous timeout error

Susheel Nuguru — Mon, 24 May 2021 18:39:54 GMT

if you have XTAL HFCLK on both peer and this device, then there are times when RC HFCLK is on before your turn on the XTAL. I would like to understand more, if you enable the same clock on both ends before the first transaction is started? and also keep using the same clocks through ? I have not seen framing errors on UART if the clocks on both devices are exactly the same. Can you please shed more light on how and where you enable the HFCLK?

RE: Serial UARTE Rx fails with continuous timeout error

Manjunath S — Mon, 24 May 2021 06:13:49 GMT

Hi,

We are using the same hardware configuration in both devices, so I doubt there will be any clock deviation. Just want to know what else could be the reason for this?

We are also using other interrupts for some sensors, could that also have any impact on this?

RE: Serial UARTE Rx fails with continuous timeout error

Susheel Nuguru — Mon, 10 May 2021 13:26:24 GMT

This error mostly happens when there is inaccuracies between the clocks used between two UART devices. You can first try to understand why how much inaccurate clock you are using on your end or on the peer's end If the inaccuracy turned out to be on the nRF device clock, then it depends on the 16M clock used. If you are using an external crystal clock, I would check the spec of that crystal to see how much this clock can deviate than the required 16MHz.

When it comes to how to handle the framing error, the easiest way is to reset the UART driver like what you already are doing. But the clocks will deviate again causing the frame error to happen soon in the future.

You should first try to understand the cause of the framing error first. Study the clocks you are using and measure the clock drifts between your clock and the peer uart clock.

RE: Serial UARTE Rx fails with continuous timeout error

Manjunath S — Mon, 10 May 2021 12:09:39 GMT

Hi,

Yes I have the error NRF_SERIAL_EVENT_DRV_ERR. and checking on the error it seems to be

NRF_UARTE_ERROR_FRAMING_MASK error in the nrf_uarte_error_mask_t.

I would like to know how to overcome this.

As of now I am just doing de-init and init of the serial instance. this works fine for some more time, again it goes into this state. this is random again, sometimes 50s sometimes 2mins. Sometimes the re-init also doesn't solve it, I get the same error till I do 4-5 re-inits

RE: Serial UARTE Rx fails with continuous timeout error

Susheel Nuguru — Mon, 10 May 2021 11:06:16 GMT

Can you please check if you have NRF_DRV_UART_EVT_ERROR before your system ends up in this state? If yes, can you tell us which error it was and how you are handling this error?