How to communicate an external module through UART in nRF9160DK?

RE: How to communicate an external module through UART in nRF9160DK?

Yusuke — Fri, 29 Mar 2019 15:50:10 GMT

yea, I'm using UART2 and it works fine

RE: How to communicate an external module through UART in nRF9160DK?

robmilne — Fri, 29 Mar 2019 12:10:34 GMT

Did you manage to get uart2 working? I need an external uart from the Arduino header while leaving the USB uarts alone.

RE: How to communicate an external module through UART in nRF9160DK?

Yusuke — Sat, 16 Mar 2019 04:14:51 GMT

I thought UART_2 module or GPIO might be broken as I input higher voltage(1.8v vs 3.3v), but it doesn't seem to be broken.

UART_1 works fine. So I replaced UART_1 with UART_2 with the same pin assignment. It works.

<.dts file>

zephyr,console = &uart2;

&uart2 {
	status = "ok";
	current-speed = <115200>;
	tx-pin = <1>;
	rx-pin = <0>;
	rts-pin = <14>;
	cts-pin = <15>;
};

Also, I toggled the voltage in P10~20. all the pins but P17,18,19 work fine. I'm using P10 for Tx and P11 for Rx so that's fine.

#include <nrf9160.h>
#include <zephyr.h>
#include <misc/printk.h>
#include <uart.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <gpio.h>

struct device *gpio_test;
int cnt = 0;

void main(void)
{
        printk("Hello, World!\r\n");
        gpio_test = device_get_binding("GPIO_0");
        if (!gpio_test) {
		printk("error gpio_test\r\n");
	}
        gpio_pin_configure(gpio_test, 10, GPIO_DIR_OUT);
        gpio_pin_configure(gpio_test, 11, GPIO_DIR_OUT);
        gpio_pin_configure(gpio_test, 12, GPIO_DIR_OUT);
        gpio_pin_configure(gpio_test, 13, GPIO_DIR_OUT);
        gpio_pin_configure(gpio_test, 16, GPIO_DIR_OUT);
        gpio_pin_configure(gpio_test, 17, GPIO_DIR_OUT);
        gpio_pin_configure(gpio_test, 18, GPIO_DIR_OUT);
        gpio_pin_configure(gpio_test, 19, GPIO_DIR_OUT);
        gpio_pin_configure(gpio_test, 20, GPIO_DIR_OUT);

        while(1){
                printk("cnt = %i\r\n", cnt);
                gpio_pin_write(gpio_test, 10, cnt % 2);
                gpio_pin_write(gpio_test, 11, cnt % 2);
                gpio_pin_write(gpio_test, 12, cnt % 2);
                gpio_pin_write(gpio_test, 13, cnt % 2);
                gpio_pin_write(gpio_test, 16, cnt % 2);
                gpio_pin_write(gpio_test, 17, cnt % 2);
                gpio_pin_write(gpio_test, 18, cnt % 2); // aloways undefined
                gpio_pin_write(gpio_test, 19, cnt % 2); // always high
                gpio_pin_write(gpio_test, 20, cnt % 2); // always low
                cnt++;
                k_sleep(1000);
        }
}

Tx is always H and releases no signal. I really appreciate it if you give me any advice.

RE: How to communicate an external module through UART in nRF9160DK?

Yusuke — Thu, 14 Mar 2019 10:54:23 GMT

nRF9160 UART logic level is originally 1.8V. I thought 3.3V.

Anyway, I disconnected P10(Tx) and saw the waveform, but always 1.8V. No signal. I have no idea of why UART signal does not come...

RE: How to communicate an external module through UART in nRF9160DK?

Yusuke — Wed, 13 Mar 2019 15:18:06 GMT

your advice is helpful.

>Have you connected another UART to the GPIOs?

Yes.

Here is my code. very simple. Any advice is helpful for me.

<main.c>
#include <nrf9160.h>
#include <zephyr.h>
#include <misc/printk.h>
#include <uart.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>

static u8_t uart_buf[1024];
static struct device *uart_wifi;

void uart_cb(struct device *_uart)
{
	uart_irq_update(_uart); // Start processing interrupts in ISR.
	int data_length = 0;

	if (uart_irq_rx_ready(_uart)) { // Check if UART RX buffer has a received char.
		data_length = uart_fifo_read(_uart, uart_buf, sizeof(uart_buf)); // Read data from FIFO.
		uart_buf[data_length] = 0;
	}
	printk("%s\r\n", uart_buf);
}

void uart_send_str(struct device *uart, char *str){
    printk("callback!\r\n");
    u32_t len = strlen(str);
    while (len--) {
        uart_poll_out(uart, *str++);
    }
}

void main(void)
{
        char *command = "AT,test\r\n";
        printk("Hello, World!\r\n");

        uart_wifi = device_get_binding("UART_2"); // "UART_1" works fine. "UART_2" does not work out.
        if (!uart_wifi) {
		printk("error\r\n");
	}
        uart_irq_rx_disable(uart_wifi);
        uart_irq_callback_set(uart_wifi, uart_cb); // Set UART interrupt callback
        uart_irq_rx_enable(uart_wifi);

	while (1) {
                printk("loop head\r\n");
                uart_send_str(uart_wifi, command);
                printk("enter sleep\r\n");
                __WFI();
	}
}

<prj.conf>

CONFIG_SERIAL=y
CONFIG_TRUSTED_EXECUTION_NONSECURE=y
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_UART_1_NRF_UARTE=y
CONFIG_UART_2_NRF_UARTE=y
CONFIG_BSD_LIBRARY_TRACE_ENABLED=n

<nrf9160_pca10090.dts>

/dts-v1/;
#include <nordic/nrf9160_xxaa.dtsi>

/ {
	model = "Nordic PCA10090 Dev Kit";
	compatible = "nordic,pca10090-dk", "nordic,nrf9160-xxaa";

	chosen {
		zephyr,console = &uart0;
                zephyr,debug = &uart1;
                zephyr,uart-wifi = &uart2;
		zephyr,sram = &sram0;
		zephyr,flash = &flash0;
	};

	aliases {
		led0 = &led0;
		led1 = &led1;
		led2 = &led2;
		led3 = &led3;
		sw0 = &button2;
		sw1 = &button3;
		sw2 = &button0;
		sw3 = &button1;
	};

	leds {
		compatible = "gpio-leds";
		led0: led_0 {
			gpios = <&gpio0 2 GPIO_INT_ACTIVE_LOW>;
			label = "Green LED 0";
		};
		led1: led_1 {
			gpios = <&gpio0 3 GPIO_INT_ACTIVE_LOW>;
			label = "Green LED 1";
		};
		led2: led_2 {
			gpios = <&gpio0 4 GPIO_INT_ACTIVE_LOW>;
			label = "Green LED 2";
		};
		led3: led_3 {
			gpios = <&gpio0 5 GPIO_INT_ACTIVE_LOW>;
			label = "Green LED 3";
		};
	};

	buttons {
		compatible = "gpio-keys";
		button0: button_0 {
			gpios = <&gpio0 8 GPIO_PUD_PULL_UP>;
			label = "Switch 1";
		};
		button1: button_1 {
			gpios = <&gpio0 9 GPIO_PUD_PULL_UP>;
			label = "Switch 2";
		};
		button2: button_2 {
			gpios = <&gpio0 6 GPIO_PUD_PULL_UP>;
			label = "Push button 1";
		};
		button3: button_3 {
			gpios = <&gpio0 7 GPIO_PUD_PULL_UP>;
			label = "Push button 2";
		};
	};

	sram0_bsd: memory@20010000 {
		device_type = "memory";
		compatible = "mmio-sram";
	};
};

&uart0 {
	status = "ok";
	current-speed = <115200>;
	tx-pin = <29>;
	rx-pin = <28>;
	rts-pin = <27>;
	cts-pin = <26>;
};

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

&uart2 {
	status = "ok";
	current-speed = <115200>;
	tx-pin = <10>;
	rx-pin = <11>;
};

...

RE: How to communicate an external module through UART in nRF9160DK?

Håkon Alseth — Wed, 13 Mar 2019 14:01:12 GMT

The behavior depends on what you do in your example.

The TXD pin should be high when idle, while the RXD pin should be floating when its not connected to another UART. Have you connected another UART to the GPIOs?

For testing reasons, you could add a loop where you send over UART2, using "uart_tx(..)" for instance.

RE: How to communicate an external module through UART in nRF9160DK?

Yusuke — Wed, 13 Mar 2019 13:24:15 GMT

Thank you for your advice!

I added "CONFIG_UART_2_NRF_UARTE=y" to a wrong file.

Building and Running were successful when I added it to correct file.

However, I can't communicate through UART yet.

Tx pin is P0.10 = Pin 3 in P19.

I checked the waveform of the Pin 3 with an oscilloscope, but there is no signal.

Do you now why?

RE: How to communicate an external module through UART in nRF9160DK?

Håkon Alseth — Wed, 13 Mar 2019 07:51:17 GMT

Did you add "CONFIG_UART_2_NRF_UARTE=y" to your prj.conf? Are you using the bsdlib in this project? It tries to use UART2 unless you add "CONFIG_BSD_LIBRARY_TRACE_ENABLED=n" to the prj.conf.

Kind regards,

Håkon

RE: How to communicate an external module through UART in nRF9160DK?

Yusuke — Tue, 12 Mar 2019 15:09:38 GMT

Thank you so much for your reply.

> I'd recommend that you use GPIOs between P0.10 and P0.20,

Get it. Then I set uart2 as shown below.

<nrf9160_pca10090.dts>

{

	chosen {
	    ..
        zephyr,uart-wifi = &uart2;
		..
	};
}

&uart2 {
	status = "ok";
	current-speed = <115200>;
	tx-pin = <10>;
	rx-pin = <11>;
};

void main(void)
{
    printk("Hello, World!\r\n");
    uart_wifi = device_get_binding("UART_2");
    if (!uart_wifi) {
    	printk("error\r\n");
	}
	..
}

However, "device_get_binding" does not work well and get error.

build is successful.

Do you know why?

RE: How to communicate an external module through UART in nRF9160DK?

Håkon Alseth — Tue, 12 Mar 2019 10:20:21 GMT

You can do that similarly as shown in the uart example here, where you alter the main.c to use UART1:

https://github.com/Rallare/fw-nrfconnect-nrf/blob/nrf9160_samples/samples/nrf9160/uart/src/main.c#L31

In prj.conf, you add:

CONFIG_UART_1_NRF_UARTE=y

And the overlay file should then hold your uart1 configuration:

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

The above pin-out goes to the virtual com port on the nRF9160-DK. If you want to connect the pins externally, I'd recommend that you use GPIOs between P0.10 and P0.20, as these are default routed out to the pin lists on the DK.

Kind regards,

Håkon

RE: How to communicate an external module through UART in nRF9160DK?

Yusuke — Mon, 11 Mar 2019 16:31:20 GMT

Thank you for your reply.

I want to use UARTs other than UART0, because UART0 is used for printk func. So how do you let nRF9160 communicate with an external module through UART1, or 2?

RE: How to communicate an external module through UART in nRF9160DK?

Håkon Alseth — Mon, 11 Mar 2019 14:58:17 GMT

Hi,

Yes, you can override the UART0 pinout using a .overlay file, as explained here:

https://devzone.nordicsemi.com/f/nordic-q-a/44114/continuous-wave-for-nrf9160/174022#174022

Note that this .overlay file must be done in both the secure_boot and the non-secure application.

Kind regards,

Håkon