UART in nrf52832

Hi I am using  UART code from nRF5_SDK_16.0.0_98a08e2\examples\peripheral.

I have checked loop back with default UART pins,which are 5,6,7,8.

Now I want to interface some sensor (Hardwired ) with this PCA10040 DK. Hence I read on Nordic community that I have to use different GPIOs.

I have changed 5,6,7,8 to 28,29,30,31 and 19,20,22,23 but in both cases loop back did not work.(I did not get data on serial port).

What am I doing wrong ? Please help

  • Hello,

    I have checked loop back with default UART pins,which are 5,6,7,8.

    By this, do you mean that you successfully built and ran the example - seeing the expected behavior as mentioned in the UART example documentation? I am just making sure I have understood you correctly.

    Now I want to interface some sensor (Hardwired ) with this PCA10040 DK. Hence I read on Nordic community that I have to use different GPIOs.

    I am not sure I understand this correctly. You may use the pins 5, 6, 7, 8. Where did you read that you had to use different GPIOS?
    Also, as a side note for future reference, it is crucial to have a look at the Pin Assignment before changing pins, if you intend to make use of the radio in your application.

    I have changed 5,6,7,8 to 28,29,30,31 and 19,20,22,23 but in both cases loop back did not work.(I did not get data on serial port).

    Was this the only modification you made to the UART example?
    Could you possibly share the code snippet of the modifications you made?

    If you are using the UART peripheral to interface with another device, then you must use RTT for the logging and debugging.
    You can use the Segger RTT as backend for the nrf_log instead of the UART. Set NRF_LOG_BACKEND_RTT_ENABLED to 1 in sdk_config.h, if you are using Segger embedded studio IDE, RTT logs can be shown directly in the IDE. If you are using a different IDE/Toolchain, you can use JLinkRTTViewer.exe. 
    The BLE peripheral Nordic UART example demonstrates how this can be done. 


    Looking forward to hearing from you,

    Best regards,
    Karl 

     

  • Hi Karl thanks for your reply.

    1.By this, do you mean that you successfully built and ran the example - seeing the expected behavior as mentioned in the UART example documentation? I am just making sure I have understood you correctly.---------->YES WHEN I SHORT THE RX,RX AND RTS,CTS for loopback test it worked and I saw the logs on serial terminal PUTTY

    2.I have read in multiple nordic posts that 5,6,7,8 are connected to Interface MCU (PCA10040) hence these pins can not be used if I want to interface (Vibration sensor in my case) external hardware on UART.

    3. There is no NRF_LOG_BACKEND_RTT_ENABLED in sdk_config.h. For your information I am using uart example from nRF5_SDK_16.0.0_98a08e2 and installed mesh sdk is v4.0. 

    4.Regarding my point 2 I want to interface external sensor which has RX,TX,RTS,CTS connections.So before connecting that sensor I thought to check loopback in new configured UART pins 28,29,30,31 OR 19,20,22,23

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     *    list of conditions and the following disclaimer.
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    /** @file
     * @defgroup uart_example_main main.c
     * @{
     * @ingroup uart_example
     * @brief UART Example Application main file.
     *
     * This file contains the source code for a sample application using UART.
     *
     */
    
    #include <stdbool.h>
    #include <stdint.h>
    #include <stdio.h>
    #include "app_uart.h"
    #include "app_error.h"
    #include "nrf_delay.h"
    #include "nrf.h"
    #include "bsp.h"
    #if defined (UART_PRESENT)
    #include "nrf_uart.h"
    #endif
    #if defined (UARTE_PRESENT)
    #include "nrf_uarte.h"
    #endif
    
    #define ENABLE_LOOPBACK_TEST
    
    
    //#define ENABLE_LOOPBACK_TEST  /**< if defined, then this example will be a loopback test, which means that TX should be connected to RX to get data loopback. */
    
    #define MAX_TEST_DATA_BYTES     (15U)                /**< max number of test bytes to be used for tx and rx. */
    #define UART_TX_BUF_SIZE 256                         /**< UART TX buffer size. */
    #define UART_RX_BUF_SIZE 256                         /**< UART RX buffer size. */
    
    void uart_error_handle(app_uart_evt_t * p_event)
    {
        if (p_event->evt_type == APP_UART_COMMUNICATION_ERROR)
        {
            APP_ERROR_HANDLER(p_event->data.error_communication);
        }
        else if (p_event->evt_type == APP_UART_FIFO_ERROR)
        {
            APP_ERROR_HANDLER(p_event->data.error_code);
        }
    }
    
    
    #ifdef ENABLE_LOOPBACK_TEST
    /* Use flow control in loopback test. */
    #define UART_HWFC APP_UART_FLOW_CONTROL_ENABLED
    
    /** @brief Function for setting the @ref ERROR_PIN high, and then enter an infinite loop.
     */
    static void show_error(void)
    {
    
        bsp_board_leds_on();
        while (true)
        {
            // Do nothing.
        }
    }
    
    
    /** @brief Function for testing UART loop back.
     *  @details Transmitts one character at a time to check if the data received from the loopback is same as the transmitted data.
     *  @note  @ref TX_PIN_NUMBER must be connected to @ref RX_PIN_NUMBER)
     */
    static void uart_loopback_test()
    {
        //printf("\r\nUART example started.\r\n");
        uint8_t * tx_data = (uint8_t *)("\r\nLOOPBACK_TEST\r\n");
        uint8_t   rx_data;
    
        // Start sending one byte and see if you get the same
        for (uint32_t i = 0; i < MAX_TEST_DATA_BYTES; i++)
        {
            uint32_t err_code;
            while (app_uart_put(tx_data[i]) != NRF_SUCCESS);
    
            nrf_delay_ms(10);
            err_code = app_uart_get(&rx_data);
    
            if ((rx_data != tx_data[i]) || (err_code != NRF_SUCCESS))
            {
                show_error();
            }
        }
        return;
    }
    #else
    /* When UART is used for communication with the host do not use flow control.*/
    #define UART_HWFC APP_UART_FLOW_CONTROL_DISABLED
    #endif
    
    
    /**
     * @brief Function for main application entry.
     */
    int main(void)
    {
        uint32_t err_code;
    
        
    
        bsp_board_init(BSP_INIT_LEDS);
    
        const app_uart_comm_params_t comm_params =
          {
              RX_PIN_NUMBER,
              TX_PIN_NUMBER,
              RTS_PIN_NUMBER,
              CTS_PIN_NUMBER,
              UART_HWFC,
              false,
    #if defined (UART_PRESENT)
              NRF_UART_BAUDRATE_115200
    #else
              NRF_UARTE_BAUDRATE_115200
    #endif
          };
    
        APP_UART_FIFO_INIT(&comm_params,
                             UART_RX_BUF_SIZE,
                             UART_TX_BUF_SIZE,
                             uart_error_handle,
                             APP_IRQ_PRIORITY_LOWEST,
                             err_code);
    
        APP_ERROR_CHECK(err_code);
    
    #ifndef ENABLE_LOOPBACK_TEST
        printf("\r\nUART example started.\r\n");
    
        while (true)
        {
            uint8_t cr;
            while (app_uart_get(&cr) != NRF_SUCCESS);
            while (app_uart_put(cr) != NRF_SUCCESS);
    
            if (cr == 'q' || cr == 'Q')
            {
                printf(" \r\nExit!\r\n");
    
                while (true)
                {
                    // Do nothing.
                }
            }
        }
    #else
    
        // This part of the example is just for testing the loopback .
        while (true)
        {
            uart_loopback_test();
        }
    #endif
    }
    
    
    /** @} */
    
    
    
    
    #define RX_PIN_NUMBER  30//8
    #define TX_PIN_NUMBER  31//6
    #define CTS_PIN_NUMBER 28//7
    #define RTS_PIN_NUMBER 29//5
    #define HWFC           false//true

  • Hi Karl,

    I am waiting for your reply.

  • I have read in multiple nordic posts that 5,6,7,8 are connected to Interface MCU (PCA10040) hence these pins can not be used

    Of course they can be used - but you have to bear in mind those other connections.

    The User Guide tells you how to break those connections:

    https://infocenter.nordicsemi.com/topic/ug_nrf52832_dk/UG/nrf52_DK/solderbridge.html

    The User Guide also says:

    "The UART signals are routed directly to the interface MCU. The UART pins connected to the interface MCU are tri-stated when no terminal is connected to the virtual COM port on the computer."

    (my emphasis)

    https://infocenter.nordicsemi.com/topic/ug_nrf52832_dk/UG/nrf52_DK/vir_com_port.html

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