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

[nvj]

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: 

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/**@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);

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

/**@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

[Sigurd]

Hi,

The old UART 2.0 app is deprecated (over 4 years since last update). I strongly recommend using the nRF-Toolbox app, and use the UART function there instead. The source code can be found here. You could also test with nRFConnect app. Let me know if you still have this issue when testing with the nRF-Toolbox and nRF Connect app.

Also, if you are creating your own app you should check out these repos:

Android-BLE-Library

Android-Scanner-Compat-Library

Android-BLE-Common-Library

Android-nRF-Blinky

[nvj]

I have tested the same on nrfConnect and I get similar issue

[nvj]

Ok. I solved the issue. Had to replace the loop with if block. Instead I used a global variable which I loop in if on condition that  (i < 500). Within if, I increment i. The enclosing function is automatically called as each time I send a string a event is raised next which generates an event which subsequently calls the enclosing function

[nvj]

Ok. I solved the issue. Had to replace the loop with if block. Instead I used a global variable which I loop in if on condition that  (i < 500). Within if, I increment i. The enclosing function is automatically called as each time I send a string a event is raised next which generates an event which subsequently calls the enclosing function