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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

Parents
  • 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

    /**
     * Copyright (c) 2014 - 2019, Nordic Semiconductor ASA
     *
     * All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without modification,
     * are permitted provided that the following conditions are met:
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     * 1. Redistributions of source code must retain the above copyright notice, this
     *    list of conditions and the following disclaimer.
     *
     * 2. Redistributions in binary form, except as embedded into a Nordic
     *    Semiconductor ASA integrated circuit in a product or a software update for
     *    such product, must reproduce the above copyright notice, this list of
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     *    materials provided with the distribution.
     *
     * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
     *    contributors may be used to endorse or promote products derived from this
     *    software without specific prior written permission.
     *
     * 4. This software, with or without modification, must only be used with a
     *    Nordic Semiconductor ASA integrated circuit.
     *
     * 5. Any software provided in binary form under this license must not be reverse
     *    engineered, decompiled, modified and/or disassembled.
     *
     * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
     * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
     * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
     * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
     * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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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

  • 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

Reply Children
  • Hi Karl,

    if I break those bridges, I understand I will not get any logs on COM PORT (putty) then in that case how should I debug my loopback test ?

    Which logs I can use to print my data on debug terminal

  • Hi,I am waiting for your reply.thanks in advance

  • Hello again,

    Sorry for my late reply - there was a national holiday in Norway yesterday.

    Gecko said:
    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.

    Well, yes and no. The pins are connected to the virtual COM port, but you do not have to break the solderbridges to use them as interface to another device. If you are going to use the UART as an interface to another device, then you may not use UART as the logging backend at the same time. I would therefor suggest using the RTT backend for logging.
    As @Awneil also emphasized, you do not have to break the solderbridges to use the UART to interface another device - the GPIOs are tri-stated when nothing is connected to the virtual COM port.
    To emphasize this, if you are running your application and communicating with your other device and then decide to open Putty to have a look at what is going on, it will not work.

    Gecko said:
    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. 

    You would have to add this to your SDK config yourself.
    For an example on how to configure this, please see the ble peripheral Nordic UART example sdk_config.
    Once you have RTT backend enabled(and UART backend disabled), you may use the Segger debug terminal, or the J-Link RTT Viewer application to see the logs.

    Gecko said:

    if I break those bridges, I understand I will not get any logs on COM PORT (putty) then in that case how should I debug my loopback test ?

    Which logs I can use to print my data on debug terminal

    This is correct, but you do not have to break those bridges to use the UART to interface another device.
    You may not have any logs on your COM port either way if you intend to use the UART to interface with another device, since there is only 1 UART instance on the nRF52832 DK.
    Changing pins of the UART will not enable you to have both UART logs and UART device interface at the same time. You may however enable RTT backend for the logger module, instead of UART, which should solve your issue.

    Best regards,
    Karl

  • Hi Karl,

    I have enabled RTT backend for logger module.And I could print logs on SES Debug Terminal using "NRF_LOG_INFO".

    So do you mean I can interface my external sensor with UART pins 5,6,7,8 without breaking those bridges and print the logs (Received UART data) on Debug Terminal ? 

    thanks in advance.

  • Hello,

    Gecko said:
    I have enabled RTT backend for logger module.And I could print logs on SES Debug Terminal using "NRF_LOG_INFO".

    Great, I am happy to hear that you got it working with RTT!

    Gecko said:
    So do you mean I can interface my external sensor with UART pins 5,6,7,8 without breaking those bridges and print the logs (Received UART data) on Debug Terminal ? 

    Yes, as long as you do not open the virtual COM port, then you may use those same pins to connect to interface with another device. You may then use the logger module to see the received UART communication on your RTT viewer.
    You do not have to break any solderbridges for this to work.

    Best regards,
    Karl

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