AT Command Uart

RE: AT Command Uart

Mariano Goluboff — Tue, 27 May 2025 14:00:53 GMT

With the default firmware, the LTE modem in the nRF9151 is not controlled via AT commands from the nRF5340 and the UARTs. The network application is running on the nRF9151's integrated application processor.

With the nRF9151, you don't need an external processor to run connectivity applications. You could reuse both UARTs for GPIOs.

RE: AT Command Uart

Øyvind — Tue, 27 May 2025 08:43:08 GMT

[quote user=""]I referenced the Thingy91_X design. [/quote]

So this is a custom design that you are working on?

[quote user="poyuankung"] I can use the UART port of the nRF5340 or another MCU connected to UART0 to operate the LTE modem via AT commands, while UART1 can be reserved and its pins kept available.[/quote]

Yes, you can use the UART ports for whatever you want. By default the UART1 is configured for modem traces, but you can use this for whatever your needs are, e.g. collecting modem traces via RTT instead.

Have a look at the Serial LTE Modem application and its associated Cellular: SLM shell sample, which can run on the nRF5340. The pre-programmed application Hello nRF Cloud firmware includes

RE: AT Command Uart

poyuankung — Mon, 26 May 2025 01:01:28 GMT

So, you're saying that I can use the UART port of the nRF5340 or another MCU connected to UART0 to operate the LTE modem via AT commands, while UART1 can be reserved and its pins kept available. It won't be used during normal operation and should only be connected when debugging the modem's behavior?"

RE: AT Command Uart

Øyvind — Fri, 23 May 2025 12:37:04 GMT

Hello,

[quote user=""] but AT commands should only require one UART.[/quote]

You can of course use it for other purposes, in our case the extra UART or VCOM is used for modem tracing.

&uart0 {
	compatible = "nordic,nrf-uarte";
	current-speed = <115200>;
	status = "okay";
	pinctrl-0 = <&uart0_default>;
	pinctrl-1 = <&uart0_sleep>;
	pinctrl-names = "default", "sleep";
};

&uart1 {
	current-speed = <1000000>;
	status = "okay";
	pinctrl-0 = <&uart1_default>;
	pinctrl-1 = <&uart1_sleep>;
	pinctrl-names = "default", "sleep";
};

In this case UART1 is intended for modem trace.

Kind regards,
Øyvind