Testing RXD and TXD Connections

[mgl]

Is there a way to test that the RXD and TXD pins are sending and receiving data on the nrf5340? I am trying to connect these pins to the u-blox ANT-B10-00C using male to female jumper cables but when I try this setup, my serial terminal is not outputting any data.

[runsiv]

Hi

I would recommend using a logic analyzer to monitor the traffic on the pins. You can also use an oscilloscope if you want to see the analog shape of the signals.  

Regards

Runar

[mgl]

Thank you. Should I use pins P0.20 and P0.22 for RXD and TXD? Would I need any other connections to communicate between my nrf5340 and ANT-B10-00C?

[runsiv]

Hi

I presume you have read https://content.u-blox.com/sites/default/files/documents/ANT-B10_SIM_UBX-22025788.pdf section 2.3 and have configured according to this. 

P.20 and P0.22 is the UART pins for the interface mcu so I would suggest to maybe use another instance of the UART and other pins. For example setting up UART2 to communicate with the UBLOX module and send the data from UART2 to UART0

Regards

Runar

[mgl]

How and where would I set this up in the Devicetree? Would it be in one of the context files?

[runsiv]

If it is the first time you are using Zephyr I would recommend that you at least have a look at the nRF Connect SDK Fundamentals course we have created to lower the doorstep to using Zephyr. Lesson 3 covers devicetree and shows you have to create an overlay file(what is used to describe the peripherals you are using) where you would need to set up uart2 and uart1. 

Regards

Runar

[mgl]

I believe I have set everything up correctly. Below is part of my overlay file for uart2. I have the RX pin of the nrf5340 connected to the TX pin of the ANT-B10-00C and the TX pin of the nrf5340 connected to the RX pin of the ANT-B10-00C. However, when I set the communication up, nothing is being outputted to my serial terminal.

 

This is the code I am trying to run: 

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

#define UART_DEVICE_NODE DT_NODELABEL(uart2)  // Use UART2

const struct device *uart_dev;

int main(void) {
    uart_dev = DEVICE_DT_GET(UART_DEVICE_NODE);

    if (!device_is_ready(uart_dev)) {
        printk("ERROR: UART2 not ready!\n");
        return -1;  // Indicate error
    }

    printk("UART2 communication test started...\n");

    const char *test_msg = "Hello ANT-B10!\r\n";

    while (1) {
        // Send message to ANT-B10
        uart_fifo_fill(uart_dev, (const uint8_t *)test_msg, strlen(test_msg));
        printk("Sent: %s", test_msg);

        k_sleep(K_MSEC(100));  // Short delay

        // Check for response
        uint8_t buffer[32];
        int recv_len = uart_fifo_read(uart_dev, buffer, sizeof(buffer) - 1);

        if (recv_len > 0) {
            buffer[recv_len] = '\0';  // Null-terminate received data
            printk("Received from ANT-B10: %s", buffer);
        } else {
            printk("No response yet...\n");
        }

        k_sleep(K_SECONDS(2));  // Repeat every 2 seconds
    }

    return 0;  // Indicate success
}

Would you happen to know why nothing is happening in my terminal?