低功耗蓝牙4.0BLE编程-nrf51822开发(11)-蓝牙串口代码分析

代码实例：Board/pca100001/06 s110/experimental/ble_app_uart。

    实现的功能是从uart口发送数据至另一个蓝牙串口，或是从蓝牙读取数据通过uart打印出数据。

[cpp]  view plain copy

 int main(void)
 {
     // Initialize
     leds_init();
     timers_init();
     buttons_init();
     uart_init();
     ble_stack_init();
     gap_params_init();
     services_init();
     advertising_init();
     conn_params_init();
     sec_params_init();

     simple_uart_putstring(START_STRING);

     advertising_start();

     // Enter main loop
     for (;;)
     {
         power_manage();
     }
 }

uart_init初始化uart的硬件。

当uart有数据时会进入uart中断处理：

[cpp]  view plain copy

 /**@brief   Function for handling UART interrupts.
  *
  * @details This function will receive a single character from the UART and append it to a string.
  *          The string will be be sent over BLE when the last character received was a 'new line'
  *          i.e '\n' (hex 0x0D) or if the string has reached a length of @ref NUS_MAX_DATA_LENGTH.
  */
 void UART0_IRQHandler(void)
 {
     static uint8_t data_array[BLE_NUS_MAX_DATA_LEN];
     static uint8_t index = 0;
     uint32_t err_code;

     /**@snippet [Handling the data received over UART] */

     data_array[index] = simple_uart_get();
     index++;

     if ((data_array[index - 1] == '\n') || (index >= (BLE_NUS_MAX_DATA_LEN - 1)))
     {
         err_code = ble_nus_send_string(&m_nus, data_array, index + 1);
         if (err_code != NRF_ERROR_INVALID_STATE)
         {
             APP_ERROR_CHECK(err_code);
         }

         index = 0;
     }

     /**@snippet [Handling the data received over UART] */
 }

data_array是数据缓冲区，当一个接收到换行符时认为是输入结束，或是达到缓冲区的最大字节数。

ble_nus_send_string函数即是把uart输入的数据通过蓝牙发送。

此实例中建立了一个服务：

 /**@brief Function for initializing services that will be used by the application.
  */
 static void services_init(void)
 {
     uint32_t         err_code;
     ble_nus_init_t   nus_init;

     memset(&nus_init, 0, sizeof(nus_init));

     nus_init.data_handler = nus_data_handler;

     err_code = ble_nus_init(&m_nus, &nus_init);
     APP_ERROR_CHECK(err_code);
 }

[cpp]  view plain copy

 uint32_t ble_nus_init(ble_nus_t * p_nus, const ble_nus_init_t * p_nus_init)
 {
     uint32_t        err_code;
     ble_uuid_t      ble_uuid;
     ble_uuid128_t   nus_base_uuid = {0x9E, 0xCA, 0xDC, 0x24, 0x0E, 0xE5, 0xA9, 0xE0,
                                      0x93, 0xF3, 0xA3, 0xB5, 0x00, 0x00, 0x40, 0x6E};

     if ((p_nus == NULL) || (p_nus_init == NULL))
     {
         return NRF_ERROR_NULL;
     }

     // Initialize service structure.
     p_nus->conn_handle              = BLE_CONN_HANDLE_INVALID;
     p_nus->data_handler             = p_nus_init->data_handler;
     p_nus->is_notification_enabled  = false;


     /**@snippet [Adding proprietary Service to S110 SoftDevice] */

     // Add custom base UUID.
     err_code = sd_ble_uuid_vs_add(&nus_base_uuid, &p_nus->uuid_type);
     if (err_code != NRF_SUCCESS)
     {
         return err_code;
     }

     ble_uuid.type = p_nus->uuid_type;
     ble_uuid.uuid = BLE_UUID_NUS_SERVICE;

     // Add service.
     err_code = sd_ble_gatts_service_add(BLE_GATTS_SRVC_TYPE_PRIMARY,
                                         &ble_uuid,
                                         &p_nus->service_handle);
     /**@snippet [Adding proprietary Service to S110 SoftDevice] */
     if (err_code != NRF_SUCCESS)
     {
         return err_code;
     }

     // Add RX Characteristic.
     err_code = rx_char_add(p_nus, p_nus_init);
     if (err_code != NRF_SUCCESS)
     {
         return err_code;
     }

     // Add TX Characteristic.
     err_code = tx_char_add(p_nus, p_nus_init);
     if (err_code != NRF_SUCCESS)
     {
         return err_code;
     }

     return NRF_SUCCESS;
 }

rx_char_add()添加了接收特性，tx_char_add()添加了发送特性。

当从蓝牙接收到数据时，通过串口将数据打印出来：

[cpp]  view plain copy

 /**@brief     Function for handling the @ref BLE_GATTS_EVT_WRITE event from the S110 SoftDevice.
  *
  * @param[in] p_dfu     Nordic UART Service structure.
  * @param[in] p_ble_evt Pointer to the event received from BLE stack.
  */
 static void on_write(ble_nus_t * p_nus, ble_evt_t * p_ble_evt)
 {
     ble_gatts_evt_write_t * p_evt_write = &p_ble_evt->evt.gatts_evt.params.write;

     if (
         (p_evt_write->handle == p_nus->rx_handles.cccd_handle)
         &&
         (p_evt_write->len == 2)
        )
     {
         if (ble_srv_is_notification_enabled(p_evt_write->data))
         {
             p_nus->is_notification_enabled = true;
         }
         else
         {
             p_nus->is_notification_enabled = false;
         }
     }
     else if (
              (p_evt_write->handle == p_nus->tx_handles.value_handle)
              &&
              (p_nus->data_handler != NULL)
             )
     {
         p_nus->data_handler(p_nus, p_evt_write->data, p_evt_write->len);
     }
     else
     {
         // Do Nothing. This event is not relevant to this service.
     }
 }