UART over BLE issues - Unable to send streaming data packets from nrf52 (ble_app_uart) to nRFUART app

I am using a ultra-miniature (BMD-350) series module from Rigdo which has the nRF52832 BLE SoC. The pins from the  nrf52 SoC are all brought out on a female headers on a custom PCB.

Firmware/SDK configuration:

  • nRF5_SDK_15.3.0_59ac345 SDK
  • pca10040 and softdevice s132  
  • nrf52832_xxaa

Debugger

  • J-Link EDU Mini debug module and using Segger Ozone software for debugging.

nrf Android Apps:

  • nrFConnect, nrF Logger and nrfUART app

I have modified the ble_app_uart example and attached the zip file of modified code.

In the main.c file, I modified the function nus_data_handler  to send dummy packets(appx. 24 bytes per packet)  to the nrfUART app by calling the function ble_nus_data_send periodically 5 seconds over BLE NUS to nrfUART app inside a loop over 500 times. Below is the  code snippet: 

/**@snippet [Handling the data received over BLE] */
static void nus_data_handler(ble_nus_evt_t * p_evt)
{
//    uint8_t rx_byte;
    NRF_LOG_INFO("[%d]nus_data_handler", order++);
    if (p_evt->type == BLE_NUS_EVT_RX_DATA)
    {
        NRF_LOG_INFO("[%d]nus_data_handler: evt=BLE_NUS_EVT_RX_DATA", order++);
        uint32_t err_code;

        NRF_LOG_DEBUG("Received data from BLE NUS. Writing data on UART.");
        NRF_LOG_HEXDUMP_DEBUG(p_evt->params.rx_data.p_data, p_evt->params.rx_data.length);

        for (uint32_t i = 0; i < p_evt->params.rx_data.length; i++)
        {
            do
            {
                err_code = app_uart_put(p_evt->params.rx_data.p_data[i]);
                if ((err_code != NRF_SUCCESS) && (err_code != NRF_ERROR_BUSY))
                {
                    NRF_LOG_ERROR("Failed receiving NUS message. Error 0x%x. ", err_code);
                    APP_ERROR_CHECK(err_code);
                }
            } while (err_code == NRF_ERROR_BUSY);

//            nrf_delay_ms(10);
//
//            err_code = app_uart_get(&rx_byte);
//            if( ( rx_byte != p_evt->params.rx_data.p_data[i] ) && err_code != NRF_SUCCESS )
//            {
//              NRF_LOG_ERROR("Failed to Loopback character 0x%x. Error: 0x%x",
//                            p_evt->params.rx_data.p_data[i],
//                            err_code );
//            }
        }

        if (p_evt->params.rx_data.p_data[p_evt->params.rx_data.length - 1] == '\r')
        {
            while (app_uart_put('\n') == NRF_ERROR_BUSY);

//            nrf_delay_ms(10);
//
//            err_code = app_uart_get(&rx_byte);
//
//            if( ( rx_byte != p_evt->params.rx_data.p_data[p_evt->params.rx_data.length - 1] ) && err_code != NRF_SUCCESS )
//            {
//              NRF_LOG_ERROR("Failed to Loopback character 0x%x. Error: 0x%x",
//                            p_evt->params.rx_data.p_data[p_evt->params.rx_data.length - 1],
//                            err_code );
//            }
        }
    }

    NRF_LOG_DEBUG("Received string %s", p_evt->params.rx_data.p_data);
    NRF_LOG_HEXDUMP_DEBUG(p_evt->params.rx_data.p_data, p_evt->params.rx_data.length);

    // If Data Received is "Requesting Data", then start sending data in a loop
//    char const * expected_str = "Requesting Data";
//    if( 0 == strncmp( (char*)(p_evt->params.rx_data.p_data), expected_str, strlen(expected_str) ) )
    {
      NRF_LOG_DEBUG("Ready to send sensor data over BLE NUS");

      uint32_t err_code;
      //char * data = "24, 0.000, 0.000, 1, D1\n";
      char data_buffer[BLE_NUS_MAX_DATA_LEN];
      // srand (time(NULL));
      // float x;
      for( int i = 0; i <500; i++)
      {
       // x = ((float)rand()/(float)(RAND_MAX)) * 0.9999;
       // sprintf(data_buffer, "24,%.2f,%d,D1\n",x, i+1);
        sprintf(data_buffer, "24,0.000,%d,D1\n", i+1);
        uint16_t length = strlen(data_buffer);
        NRF_LOG_DEBUG("Sending over BLE. Data length: %d, Data: %s", length, data_buffer);
        do
        {
          err_code = ble_nus_data_send(&m_nus, (uint8_t*)data_buffer, &length, m_conn_handle);
          if ((err_code != NRF_ERROR_INVALID_STATE) &&
              (err_code != NRF_ERROR_RESOURCES) &&
              (err_code != NRF_ERROR_NOT_FOUND))
          {
              APP_ERROR_CHECK(err_code);
          }
        } while (err_code == NRF_ERROR_RESOURCES);
        nrf_delay_ms(5000);
      }
    }
//    else
//    {
//      NRF_LOG_DEBUG("Not received required string!");
//    }
}
/**@snippet [Handling the data received over BLE] */

While I do receive first 12 packets on nRFUART app but thereafter I stop receiving anything even though I should continue to receive remaining 489 of 500 dummy packets. The Bluetooth connection also gets disconnected and I dont see the nrf52 advertising. Thereafter, I have to reset my nRF52 to make new Bluetooth connection and restart this process.

I have tried manipulating buffer sizes used by ble_nus_data_send as well as UARt bufffers, but nothing seems to work. Either I get run-time error or issue remains.

What is the proper way to send streaming data packets to the nrfUART from nrf52 continuously using the  BLE UART service ?

ble_app_uart.zip

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