AT Command Uart

[poyuankung]

HI Teams

I referenced the Thingy91_X design. The MCU nRF5340 connects to the nRF9151 using two UART interfaces, but AT commands should only require one UART.

Under what circumstances is the second UART needed? In what situations can it be released for use as other GPIOs?

[Øyvind]

Hello, 

but AT commands should only require one UART.

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

[poyuankung]

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?"