Problem using UART using NCS 2.9.0

[d_7]

Hi,

I've just migrated my project from NCS 2.6.1 to 2.9.0 and I'm having some problems with the UART.

I'm using the nRF52833 DK to communicate with another device and I noticed that I can send data from the nRF to the other device, however, I can't send data from the device to the nRF.

I decided to test with an example from Nordic (UART echo bot) and noticed that when I use the default pins of the UART, the communication works as it should (nRF <-> device). However, when I switch to the pins I'm using in the main project, communication only works in one direction (nRF -> device), i.e. there's no more communication (nrf <- device).

These are the pins I'm using:

&uart0 {
    hw-flow-control;    // Enable RTS and CTS
    current-speed = <115200>;
	data-bits = <8>;
	stop-bits = "1";
	parity = "none";
    pinctrl-0 = <&uart0_default_alt>;
    pinctrl-1 = <&uart0_sleep_alt>;
    status = "okay";
};
 
&pinctrl {
    uart0_default_alt: uart0_default_alt {
            
        group1 {
            psels = <NRF_PSEL(UART_TX, 0, 30)>,
                    <NRF_PSEL(UART_RX, 0,  8)>,
                    <NRF_PSEL(UART_RTS, 0, 6)>,
                    <NRF_PSEL(UART_CTS, 0, 7)>;
        };
        
    };
    uart0_sleep_alt: uart0_sleep_alt {
        group1 {
            psels = <NRF_PSEL(UART_TX, 0, 30)>,      
                    <NRF_PSEL(UART_RX, 0,  8)>,      
                    <NRF_PSEL(UART_RTS, 0, 6)>,     
                    <NRF_PSEL(UART_CTS, 0, 7)>;     
            
                    low-power-enable;
        };
    };
};

I disabled spi, i2c, adc, leds and buttons to make sure that there were no conflicts between pins.

Thank you!

[Kazi Afroza Sultana]

Hello,

The default pin number of MOSI is P0.30 in the default pincontrol (nrf52833dk_nrf52820-pinctrl.dtsi) file (C:\ncs\v2.9.0\zephyr\boards\nordic\nrf52833dk\nrf52833dk_nrf52820-pinctrl.dtsi)). 

'I disabled spi, i2c, adc, leds and buttons to make sure that there were no conflicts between pins.''

Can you share the board file of your application with me then I can see if disabling the peripheral is ok or not? 

''However, when I switch to the pins I'm using in the main project, communication only works in one direction (nRF -> device), i.e. there's no more communication (nrf <- device).

Do you have any output log that you can share with us?

Thanks.

BR

Kazi

[d_7]

Hello,

These are my project files:

Fullscreen 7510.main.c Download

/*
 * Copyright (c) 2022 Libre Solar Technologies GmbH
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/drivers/uart.h>

#include <string.h>

/* change this to any other UART peripheral if desired */
#define UART_DEVICE_NODE DT_CHOSEN(zephyr_shell_uart)

#define MSG_SIZE 32

/* queue to store up to 10 messages (aligned to 4-byte boundary) */
K_MSGQ_DEFINE(uart_msgq, MSG_SIZE, 10, 4);

static const struct device *const uart_dev = DEVICE_DT_GET(UART_DEVICE_NODE);

/* receive buffer used in UART ISR callback */
static char rx_buf[MSG_SIZE];
static int rx_buf_pos;

/*
 * Read characters from UART until line end is detected. Afterwards push the
 * data to the message queue.
 */
void serial_cb(const struct device *dev, void *user_data)
{
	uint8_t c;

	if (!uart_irq_update(uart_dev)) {
		return;
	}

	if (!uart_irq_rx_ready(uart_dev)) {
		return;
	}

	/* read until FIFO empty */
	while (uart_fifo_read(uart_dev, &c, 1) == 1) {
		if ((c == '\n' || c == '\r') && rx_buf_pos > 0) {
			/* terminate string */
			rx_buf[rx_buf_pos] = '\0';

			/* if queue is full, message is silently dropped */
			k_msgq_put(&uart_msgq, &rx_buf, K_NO_WAIT);

			/* reset the buffer (it was copied to the msgq) */
			rx_buf_pos = 0;
		} else if (rx_buf_pos < (sizeof(rx_buf) - 1)) {
			rx_buf[rx_buf_pos++] = c;
		}
		/* else: characters beyond buffer size are dropped */
	}
}

/*
 * Print a null-terminated string character by character to the UART interface
 */
void print_uart(char *buf)
{
	int msg_len = strlen(buf);

	for (int i = 0; i < msg_len; i++) {
		uart_poll_out(uart_dev, buf[i]);
	}
}

int main(void)
{
	char tx_buf[MSG_SIZE];

	if (!device_is_ready(uart_dev)) {
		printk("UART device not found!");
		return 0;
	}

	/* configure interrupt and callback to receive data */
	int ret = uart_irq_callback_user_data_set(uart_dev, serial_cb, NULL);

	if (ret < 0) {
		if (ret == -ENOTSUP) {
			printk("Interrupt-driven UART API support not enabled\n");
		} else if (ret == -ENOSYS) {
			printk("UART device does not support interrupt-driven API\n");
		} else {
			printk("Error setting UART callback: %d\n", ret);
		}
		return 0;
	}
	uart_irq_rx_enable(uart_dev);

	print_uart("Hello! I'm your echo bot.\r\n");
	print_uart("Tell me something and press enter:\r\n");

	/* indefinitely wait for input from the user */
	while (k_msgq_get(&uart_msgq, &tx_buf, K_FOREVER) == 0) {
		print_uart("Echo: ");
		print_uart(tx_buf);
		print_uart("\r\n");
	}
	return 0;
}

3301.prj.conf4466.nrf52833dk_nrf52833.overlay

Regarding the output, I don't have nothing that can help. But I can try to explain the problem better.

I have a USB serial converter connected to a PC with hterm (PC B). And a nRF52833 DK connected to other PC with nRF Connec for VS Code (PC A).

Using the default UART pins of the nRF52833 DK, I send “test1” via VCOM0 from PC A to PC B and the data appears in PC B hterm. Then, for example, I send “test1_ans” via PC B hterm and this data appears on PC A.

When I change the pins to those described above, I send “test1” via VCOM0 from PC A to PC B and the data appears in PC B hterm. However, when I send “test1_ans” via PC B hterm, this data does not appear on PC A.

Thank you