How can I output log information on my nrf9160 board?

[duxinglang]

I have designed a nrf9160 debugging board, which uses 18 and 19 pin as the log output. Then I also configure the TX and Rx of UART0 in the overlay file, which are 18 and 19 respectively. However, when I connect to the PC with the serial port cable, I find that there is no log information output. How can I do this?

&uart0{
	status = "okay";
	current-speed = <115200>;
	tx-pin = <18>;
	rx-pin = <19>;
	#rts-pin = <14>;
	#cts-pin = <15>;
};

[duxinglang]

Now，I can modify the uart0 tx-pin and rx-pin in the nrf9160_pca10090_common.dts file directly , and now it can output log. However, all AT instructions are invalid, and from the monitor interface, many functions are limited. Why?

&gpio0 {
	status = "okay";
};

&uart0 {
	status = "okay";
	current-speed = <115200>;
	tx-pin = <31>;
	rx-pin = <30>;
	rts-pin = <27>;
	cts-pin = <26>;
};

&uart1 {
	status = "okay";
	current-speed = <115200>;
	tx-pin = <1>;
	rx-pin = <0>;
	rts-pin = <14>;
	cts-pin = <15>;
};

[duxinglang]

It seems that the at command does not correspond

[Martin Lesund]

Hi Duxinglang,

Please make sure that you have set the correct pin, and I would also advice you to reset the LTE link Monitor. (sometimes you can get similar symptom, but fix it with just a restart)

You could also test out another Serial Terminal, Such as Termite and make sure you have the correct command ending: 

I would also like you to just run the plain AT client sample when testing this.

To make the overlay work, make sure you have the correct name for that file.

This is also described in the NCS tutorials:

• NCS Tutorial - Part 0
• NCS Tutorial - Part 1
• NCS Tutorial - Part 2
• NCS Tutorial - Part 3

[duxinglang]

I have rebooted the LTE link Monitor many times, but it still can't execute the at command. Because I have seen the log output, it's not the pin problem, and it shouldn't be the cause of CR-LF, If I connect the PC with the USB interface of DK board, it can execute these at commands. So I wonder if IF-MCU has any other control over at commands?

[Martin Lesund]

Hi Duxinglang,

Do you only use tx and the rx pins? or have the rts-pin and cts-pin connected?
If you are using flow-control on NCS v1.3.0 you need to enable "hw-flow-control" in the .overlay file.

Please test with the at-client sample.

You can also use this guide as reference posted in this devzone thread.

[duxinglang]

Yes, i only use tx and rx pins, my project is base on NCS v1.2.0.

[Martin Lesund]

Please try to use another serial terminal, e.g. Termite.

Another thing you could do is connect a logic analyzer to the UART pins to if it behaves correctly.

You could also debug your code and check if the UART callback handler is triggered when you try to send an AT command to the nrf9160