How to config device tree to use UART00 or UART21 for TXD output to P2.08

[John So]

Hi,

I get a PCBA which contains the following test points of nRF54L15 :  P0.02, P0.03, P2.07, P2.08. I would like to set one of them to be UART TXD. 

In pin assignment, I checked that P2.8 can be used as TXD of UART00 or UART21.

However, I tried to det following in the .dts , I will get build error:

&pinctrl {
   /omit-if-no-ref/ uart00_default: uart00_default {

   group1 {
   psels = <NRF_PSEL(UART_TX, 2, 8)>;

  };
  group2 {
psels = <NRF_PSEL(UART_RX, 2, 7)>;
bias-pull-up;
};
};

/omit-if-no-ref/ uart00_sleep: uart00_sleep {

group1 {
psels = <NRF_PSEL(UART_TX, 2, 8)>,
<NRF_PSEL(UART_RX, 2, 7)>;
low-power-enable;
};


};

....

&uart00 {
current-speed = <115200>;
pinctrl-0 = <&uart00_default>;
pinctrl-1 = <&uart00_sleep>;
pinctrl-names = "default", "sleep";
};

Same issue if I use uart21.

Would you inform how can I set the dts in oder to use UART00 or UART21?

Rgds

John

[Menon]

hello,

Could you please share the build log showing the exact error message you’re getting, and also check the generated device tree (build/app/zephyr/zephyr.dts) after the build? It would be helpful to see whether the UART you’re trying to use (uart00 or uart21) is actually present and enabled there, along with its pinctrl configuration, as this should clarify whether the issue is coming from the board configuration or the DTS setup.

Kind Regards,

Abhijith

[John So]

Hi Abhijith,

The build issue is fixed. The root cause is:  I have not set status = "okay" for the UART module (UART00 or 21).

However, it finds that for P2.07/P2.08, I can only use UART00 but not UART21. If I use UART21 on P2.08, it can build the firmware but the firmware cannot run.

On the product spec, it states that either UART00 or UART21 can be used on those pins.

Would you help to find out why UART21 cannot be used on P2.07/P2.08?

Is there any setting in the nRF54L15DK board restrict the use of UART21 on P2.08?

Best Regards

John