nRF9160 UARTE communication between 91 and 52 is unreliable

RE: nRF9160 UARTE communication between 91 and 52 is unreliable

Carl Richard — Tue, 08 Sep 2020 14:13:07 GMT

Ah, I should have read the code more thoroughly.

Just to test could you rewrite your nRF9160 .overlay like this:

&uart2 {
      compatible = "nordic,nrf-uarte";
      current-speed = <115200>;
      status = "okay";
      tx-pin = <10>;
      rx-pin = <11>;
      rts-pin = <12>;
      cts-pin = <13>;
      hw-flow-control;
};

In addition, do you have a logic analyzer available? It could help to see what's happening on the different pins.

Lastly, this seems to be a timing issue of some sort (as you suggest). I have read through some old cases regarding data loss over UARTE on the nRF52840 and found that it could be problems with the clock. Could you try the fix in this thread too?

Best regards,
Carl Richard

RE: nRF9160 UARTE communication between 91 and 52 is unreliable

HAFLN — Tue, 08 Sep 2020 09:24:21 GMT

Good morning Carl,

I believe we are using Easy DMA on both ends:

nRF91:

CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_UART_2_NRF_UARTE=y

nRF52:

NRF_SERIAL_CONFIG_DEF(m_serial_config, NRF_SERIAL_MODE_DMA,

RE: nRF9160 UARTE communication between 91 and 52 is unreliable

Carl Richard — Tue, 08 Sep 2020 08:03:20 GMT

Hi again, HAFLN.

It could be that you there are timing conflicts between UART and the softdevice/BLE operation, yes. If I'm not mistaken you are using UART without easy DMA, which could starve the CPU of resources when running the BLE stack in addition.

Could you try to enable UARTE?

Best regards,
Carl Richard

RE: nRF9160 UARTE communication between 91 and 52 is unreliable

HAFLN — Mon, 07 Sep 2020 15:24:29 GMT

Thanks Carl!

Sorry, my mistake I sent the wrong pin settings for nRF52840 in my question (I had board settings for a wrong board open).

The actual pins are as you suggested and the problem stills stands: we are loosing big chunks of UART transmissions intermittently.

Just a wild guess but could this be something to do with softdevice? Since once nRF52 is provisioned UART communication improves.

RE: nRF9160 UARTE communication between 91 and 52 is unreliable

Carl Richard — Mon, 07 Sep 2020 07:55:02 GMT

Hello, HAFLN!

I suspect the unreliability is related to your pin assignments. The nRF52840 of the nRF9160DK acts as the board controller and is thus very limited in terms of available GPIO. Hence, I recommend trying the pin assignments used for the nRF9160 and the nRF5240 in the LTE BLE gateway example. You already use the correct pins for the nRF9160. The nRF5240 is as follows:

&uart1 {
	compatible = "nordic,nrf-uarte";
	current-speed = <1000000>;
	status = "okay";
	tx-pin = <17>;
	rx-pin = <20>;
	rts-pin = <15>;
	cts-pin = <22>;
};

This is from an overlay file, but you can use this to get the correct pin defines in your nRF Mesh code.

Hope this works!

Best regards,
Carl Richard