Pin assignment for UART on the nRF54L15DK

[a.da]

Hello.

I am testing UART connectivity using the nRF54L15DK.

After assigning pins to TX and RX, there were combinations that worked fine and combinations that didn't.
There are no build errors. The program starts up successfully, but UART communication doesn't work.
In both cases, there doesn't appear to be any conflict with other pins.
Even after explicitly removing "uart30_default" and "uart30_sleep" where P0.0 and P0.1 are used, the results didn't change.
Since RST and CST are not being used, I haven't assigned them.

The "nrf54l15dk_nrf54l15_cpuapp.overlay" is as follows. Everything is the same except for this file.
Is there any configuration oversight or constraint?

OK

/ {
	chosen {
		nordic,nus-uart = &uart21;
	};
};

&uart21 {
	status = "okay";
	current-speed = <9600>;
	pinctrl-0 = <&uart21_default_alt>;
	pinctrl-1 = <&uart21_sleep_alt>;
	pinctrl-names = "default", "sleep";
	/delete-property/ endtx-stoptx-supported;
	/delete-property/ frame-timeout-supported;
};

&pinctrl {
	uart21_default_alt: uart21_default_alt {
		group1 {
			psels = <NRF_PSEL(UART_TX, 1, 11)>, <NRF_PSEL(UART_RX, 1, 12)>;
		};
	};
	uart21_sleep_alt: uart21_sleep_alt {
		group1 {
			psels = <NRF_PSEL(UART_TX, 1, 11)>, <NRF_PSEL(UART_RX, 1, 12)>;
			low-power-enable;
		};
	};
};

NG

/ {
	chosen {
		nordic,nus-uart = &uart30;
	};
};

&uart30 {
	status = "okay";
	current-speed = <9600>;
	pinctrl-0 = <&uart30_default_alt>;
	pinctrl-1 = <&uart30_sleep_alt>;
	pinctrl-names = "default", "sleep";
	/delete-property/ endtx-stoptx-supported;
	/delete-property/ frame-timeout-supported;
};

&pinctrl {
	/delete-node/ uart30_default;
	/delete-node/ uart30_sleep;
	uart30_default_alt: uart30_default_alt {
		group1 {
			psels = <NRF_PSEL(UART_TX, 0, 0)>, <NRF_PSEL(UART_RX, 0, 1)>;
		};
	};
	uart30_sleep_alt: uart30_sleep_alt {
		group1 {
			psels = <NRF_PSEL(UART_TX, 0, 0)>, <NRF_PSEL(UART_RX, 0, 1)>;
			low-power-enable;
		};
	};
};

Thanks for reading.

a.da

[Simonr]

Hi

By default the pins P0.00-P0.03 are connected to the IMCU on the nRF54L15 DK and are used for UART logging already as the "nRF54L15 UART_0 - Serial Port 0", so these are probably already defined which is likely why you're not able to use them yourself like this. This is specified in the nRF54L15 DK user guide here: http://docs.nordicsemi.com/bundle/ug_nrf54l15_dk/page/UG/nRF54L15_DK/program_debug/virtual_serial_ports.html 

Best regards,

Simon

[a.da]

Simonr 

I apologize, but may I confirm something?

The Devicetree Visual Editor in VS Code does not display the assignment for 'Serial Port 0'. Is that how it is supposed to be?

uart30' is a definition I specified in the overlay file.
For example, when there is a conflict in pin assignments like with P0.00, all the assignments are displayed for the pin.
'Serial Port 1' (P1.04-P1.07) is displayed as 'uart20', but 'Serial Port 0' is not shown.