How to make LOG_INF and LOG_ERR print over UART0 in nrf9160?

RE: How to make LOG_INF and LOG_ERR print over UART0 in nrf9160?

JWizard — Wed, 31 Mar 2021 20:13:08 GMT

Hi Markus,

So I kept trying different things and I came up with something that seems to work okay.

I completely removed the .overlay from the SPM folder and changed my overlay in the mqtt_simple folder to

&uart0 {
current-speed = <115200>;
status = "okay";
tx-pin = <1>;
rx-pin = <0>;
rts-pin = <0xFFFFFFFF>;
cts-pin = <0xFFFFFFFF>;
};

&uart1 {
current-speed = <115200>;
status = "okay";
tx-pin = <29>;
rx-pin = <28>;
rts-pin = <27>;
cts-pin = <26>;
};

Basically I just swapped the pins and disabled the RTS and CTS for UART0. Seems like it really wanted UART1 to be enabled, because now I get this on my external MCU (edited to remove anything that might be identifying)

*** Booting Zephyr OS build v2.4.99-ncs1 ***
[00:00:00.205,566] <inf> at_host: UART check failed: 12. Dropping buffer and retrying.
[00:00:00.215,667] <inf> mqtt_simple: The MQTT simple sample started
[00:00:00.215,667] <inf> mqtt_simple: Provisioning certificates
[00:00:00.537,261] <inf> mqtt_simple: Disabling PSM and eDRX
[00:00:00.544,799] <inf> mqtt_simple: LTE Link Connecting...
+CEREG: **REDACTED**
+CSCON: 1
+CEREG: **REDACTED**
[00:00:08.957,733] <inf> mqtt_simple: LTE Link Connected!
[00:00:09.139,678] <inf> mqtt_simple: IPv4 Address found **REDACTED**
[00:00:09.139,709] <inf> mqtt_simple: TLS enabled
[00:00:13.368,621] <inf> mqtt_simple: MQTT client connected
[00:00:13.368,621] <inf> mqtt_simple: Subscribing to: **REDACTED** len 16
[00:00:13.547,607] <inf> mqtt_simple: SUBACK packet id: 1234

So far so good, only why does it say "at_host: UART check failed?" Best guess is at_host wanted to check UART 1 and nothing is connected to pins 26-29. On the up side I can issue AT commands and I get responses and everything checks out.

On the down side I've got an error message in the bootup that I don't understand. If I can use at_host through UART0 why is UART1 necessary and what is the true meaning of the error message?

I'll mark this as the answer anyway since it answers the question I asked directly.

RE: How to make LOG_INF and LOG_ERR print over UART0 in nrf9160?

JWizard — Wed, 31 Mar 2021 15:17:19 GMT

Hi Markus,

I received the information about the second overlay file here: https://devzone.nordicsemi.com/f/nordic-q-a/64677/changing-uart0-pins-for-custom-nrf9160-board

This file was located at ncs/v1.5.0/nrf/samples/spm

I removed it and rebuilt. It doesn't seem to have made any difference either way.

RE: How to make LOG_INF and LOG_ERR print over UART0 in nrf9160?

Albrecht Markus Schellenberger — Wed, 31 Mar 2021 14:51:14 GMT

Thanks for the clarification!

The changes you made in nrf9160dk_nrf9160ns.overlay look correct to me.

But I wonder why you added one more overlay file in the SPM directory? I’m not sure if this is necessary. Where exactly is the file located in your project?

Regards,

Markus

RE: How to make LOG_INF and LOG_ERR print over UART0 in nrf9160?

JWizard — Tue, 30 Mar 2021 17:19:50 GMT

Hi Markus,

Thank you for the quick reply.

My zephyr.dts checks out exactly as you show given the changes I wanted to see.

uart0: uart@8000 {
compatible = "nordic,nrf-uarte";
reg = < 0x8000 0x1000 >;
interrupts = < 0x8 0x1 >;
status = "okay";
label = "UART_0";
current-speed = < 0x1c200 >;
tx-pin = < 0x1 >;
rx-pin = < 0x0 >;
rts-pin = < 0xffffffff >;
cts-pin = < 0xffffffff >;

chosen {
zephyr,flash-controller = &flash_controller;
zephyr,entropy = &cryptocell_sw;
zephyr,console = &uart0;
zephyr,shell-uart = &uart0;
zephyr,uart-mcumgr = &uart0;
zephyr,flash = &flash0;
zephyr,sram = &sram0_ns;
zephyr,code-partition = &slot0_ns_partition;
};

It was already like this, but I did a fresh build anyway. No change in behavior. Nothing on UART0, not even the boot messages if I reset the chip.

Let me clarify how I do the overlays in case something has changed since this method was given to me:

1) In the mqtt_simple project directory I placed a new file called nrf9160dk_nrf9160ns.overlay (note the "ns")

&uart1 {
status = "disabled";
};

&uart0 {
current-speed = <115200>;
status = "okay";
tx-pin = <1>;
rx-pin = <0>;
rts-pin = <0xFFFFFFFF>;
cts-pin = <0xFFFFFFFF>;
};

2) In the SPM directory I added nrf9160dk_nrf9160.overlay (note the lack of "ns")

/* Needed to get NRF_PWMn defined. */
&pwm1 {
status = "okay";
};

&pwm2 {
status = "okay";
};

&pwm3 {
status = "okay";
};

&uart0 {
current-speed = <115200>;
status = "okay";
tx-pin = <1>;
rx-pin = <0>;
rts-pin = <0xFFFFFFFF>;
cts-pin = <0xFFFFFFFF>;
};

The PWM stuff was already there.

Adding these lines in ncs V1.3.1 allowed me to run the at_client or the serial_lte_modem application on my custom board. I could issue AT commands over UART0 from my external mcu, and see the responses. I would see the bootup messages over UART0 when I reset the chip.

I use Segger Embedded Studio. When I "Open NRF SDK project..." I select nrf9160dk_nrf9160ns as the Board Name.

Also, I just tried this method on the ncs/v1.5.0/nrf/samples/nrf9160/at_client and it did not work.

It works on the ncs v1.3.1 and does not work on ncs v1.5.0

RE: How to make LOG_INF and LOG_ERR print over UART0 in nrf9160?

Albrecht Markus Schellenberger — Tue, 30 Mar 2021 14:18:30 GMT

Hello,

you can check a couple of things in the zephyr.dts file, which is located in the ../build/zephyr folder of your application.

1. The UART0 device should have the same properties as specified in the overlay file (see example below, which is from an application build without overlay for target nrf9160dk_nrf9160).

uart0: uart@8000 {
				compatible = "nordic,nrf-uarte";
				reg = < 0x8000 0x1000 >;
				interrupts = < 0x8 0x1 >;
				status = "okay";
				label = "UART_0";
				current-speed = < 0x1c200 >;
				tx-pin = < 0x1d >;
				rx-pin = < 0x1c >;
				rts-pin = < 0x1b >;
				cts-pin = < 0x1a >;
			};

2. UART0 must be assigned to zephyr,console in the /chosen node.

chosen {
		zephyr,flash-controller = &flash_controller;
		zephyr,entropy = &cryptocell_sw;
		zephyr,console = &uart0;
		zephyr,shell-uart = &uart0;
		zephyr,uart-mcumgr = &uart0;
		zephyr,flash = &flash0;
		zephyr,sram = &sram0_ns;
		zephyr,code-partition = &slot0_ns_partition;
	};

Let me know if you have any more questions!

Regards,

Markus