RE: Best way to detect when a client subscribes to the NUS

user112414 — Thu, 12 May 2022 08:48:47 GMT

thanks, this works very well.

RE: Best way to detect when a client subscribes to the NUS

user4240 — Thu, 12 May 2022 07:34:33 GMT

Hi,

The NUS service will actually raise an event when notifications are enabled/disabled by the client, but the ble_app_uart example does not subscribe for these events by default so it might be easy to overlook. You can "subscribe" for these events in the nus_data_handler():

/**@brief Function for handling the data from the Nordic UART Service.
 *
 * @details This function will process the data received from the Nordic UART BLE Service and send
 *          it to the UART module.
 *
 * @param[in] p_evt       Nordic UART Service event.
 */
/**@snippet [Handling the data received over BLE] */
static void nus_data_handler(ble_nus_evt_t * p_evt)
{

    
    switch (p_evt->type) 
    {
        case BLE_NUS_EVT_RX_DATA:
        {
    
            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);
            }
            if (p_evt->params.rx_data.p_data[p_evt->params.rx_data.length - 1] == '\r')
            {
                while (app_uart_put('\n') == NRF_ERROR_BUSY);
            }
        } break;

        case BLE_NUS_EVT_COMM_STARTED:
            NRF_LOG_INFO("Notifications enabled");
            break;
       
        case BLE_NUS_EVT_COMM_STOPPED:
            NRF_LOG_INFO("Notifications disabled");
            break;

        default:
            break;
    }

}

Best regards,

Vidar