5.1.2.7 BLE Custom Service

Recommended Readings

1. Getting Started with Application Building Blocks – See Building Block Examples from Related Links.

2. Getting Started with Peripheral Building Blocks – See Peripheral Devices from Related Links.

3. See BLE Connection from Related Links.
4. See BLE Custom Service from Related Links.

5. BLE Software Specification – See MPLAB® Harmony Wireless BLE in Reference Documentation from Related Links.

Hardware Requirement

SDK Setup

Software

Smartphone App

Light Blue iOS/Android app available in stores

Programming the Precompiled Hex File or Application Example

Using MPLAB® X IPE:

Using MPLAB® X IDE:

1. Perform the following the steps mentioned in Running a Precompiled Example. For more information, refer to Running a Precompiled Application Example from Related Links.
2. Open and program the application <Harmony Content Path>\wireless_apps_pic32_bz6\apps\ble\building_blocks\peripheral\profiles_services\custom_service\firmware\custom_service.X.
3. For more details on how to find the Harmony Content Path, refer to Installing the MCC Plugin from Related Links.

Demo Description

This application enables users to control a RGB LED on the PIC32-BZ6 Curiosity board and read its status using a central device. On reset, demo will print “[BLE] Device Initialized. Ready for connection” which denotes the start of advertisements and then “[BLE] Connected to Peer Device”: when connection is established. Application data to be sent to the connected central device (smartphone or another PIC32-BZ6 Curiosity board) is entered in a terminal emulator like Tera Term.

Testing

1. Using a micro USB cable, connect the Debug USB on the Curiosity board to a PC.
2. Program the precompiled hex file or application example as mentioned.
3. Open TeraTerm and configure as mentioned below:
   Terminal Settings:

   • Baud Rate/Speed – 115200 (as configured in SERCOM configuration)
   • Parity – None
   • Data Bits – 8
   • Stop Bits – 1
   • Flow Control – None
   For more details on how to set the “Serial Port” and “Speed”, refer to COM Port Setup in Running a Precompiled Application Example from Related Links.
4. Press the NMCLR button on the Curiosity board. This must be displayed in Tera Term.

   

5. Launch the Light Blue mobile app and search for the device name “pic32cx-bz6” and press Connect. Users with an iOS device may see the device name as “Microchip”.

   

   

6. Once connected, basic information like Advertisement Data and Device Information will be available.

   

7. Find the custom service with the UUID: 4d434850-5255-42d0-aef8-881facf4ceea. Two characteristics will be available with the custom service. The button characteristics with the Readable/Notify property and RGB LED characteristics with Readable/Writable property.

   

8. Click on the button characteristics and press subscribe. Press the User button 2 on the curiosity board. The Read Value in the app will give its current status. Pressing the button will also toggle the RGB LED.

   

   

9. Go back and click on the RGB LED characteristics which has a read/write option. The write option changes the RGB LED Colour by writing a hex value in the form of XXXXXX. A value of 000000 will turn OFF the LED and value of FFFFFF turns the Red, Green and Blue LED of RGB LED ON. The read option will give the current value stored for the RGB LED.

   

   

10. Press back two times to disconnect the BLE connection. A disconnected device will advertise again.

    

Developing the Application from Scratch using MCC

1. Create a new harmony project. For more details, see Creating a New MCC Harmony Project from Related Links.
2. To setup the basic components and configuration required to develop this application, import component configuration: <Harmony Content Path>\wireless_apps_pic32_bz6\apps\ble\building_blocks\peripheral\profiles_services\custom_service\firmware\custom_service.X\custom_service.mc.
   Note: Import and Export functionality of the Harmony component configuration will help users to start from a known working setup of the MCC configuration.
3. Accept dependencies or satisfiers when prompted.
4. Verify if the project graph window has all the expected configuration.

   

Verify Custom Service Configuration

1. Select BLE Stack component the Project Graph and configure the following in the Configuration Options panel.

   Note: If users cannot see the Configuration Options panel in the right-hand side of the MPLAB X IDE, it might be minimized. Hover the cursor towards the Configuration Options side tab and click the “dot” on the top right-hand corner to pin it (see the following figure).

   

   .
2. Select the FreeRTOS component in the Project Graph and configure the following.

   

3. Select the SERCOM0 component in the Project Graph and configure the following.

   

4. Select the System component in the Project Graph and configure the following.

   

5. Select the EIC component in the Project Graph and configure the following.

   

6. Select the Customized Service component in the Project Graph and configure the following.

   

   

   

Generating a Code

For more details on code generation, refer to MPLAB Code Configurator (MCC) Code Generation from Related Links.

Files and Routines Automatically generated by the MCC

After generating the program source from the MCC interface by clicking Generate Code, the BLE configuration source and header files can then be found in the following project directories.

Initialization routines for OSAL, RF System, and BLE System are auto-generated by the MCC. See OSAL Libraries Help in Reference Documentation from Related Links. Initialization routine executed during program initialization can be found in the project file.

The BLE stack initialization routine executed during Application Initialization can be found in project files. This initialization routine is automatically generated by the MCC. This call initializes and configures the GAP, GATT, SMP, L2CAP and BLE middleware layers.

Autogenerated, Advertisement Data Format

User Application Development

Add the code to enable advertisement, call the button external interrupt callback functions and initialize custom service in APP_STATE_INIT of the function APP_Tasks() in app.c

 /* Application's initial state. */
 case APP_STATE_INIT:
 {  
    bool appInitialized = true;
    //appData.appQueue = xQueueCreate( 10, sizeof(APP_Msg_T) );
    APP_BleStackInit();
    BLE_GAP_SetAdvEnable(0x01, 0); //Enable BLE Advertisement
    BLE_BUTTON_LED_Add();
    APP_Button_Init();
    SYS_CONSOLE_PRINT("[BLE] Device Initialized. Ready for connection. \r\n");

Add the GREEN LED and button handlers to the function APP_Tasks() in app.c

 case APP_STATE_SERVICE_TASKS:
 { 
    if (OSAL_QUEUE_Receive(&appData.appQueue, &appMsg, OSAL_WAIT_FOREVER))
    {
     switch (p_appMsg->msgId)
     {
        case APP_MSG_BLE_STACK_EVT:
        {
            APP_BleStackEvtHandler((STACK_Event_T *)p_appMsg->msgData);
         }
         break;
         case APP_MSG_BLE_CS_LED_EVT:
         {
             APP_CustomService_RGB_Handler((uint8_t *)((STACK_Event_T *)p_appMsg->msgData));
          }
          break;
          case APP_MSG_BLE_CS_BUTTON_EVT:
          {
              APP_CustomService_Button_Handler();
          }
          break;
       }
   }
  break;
 }

Add the message IDs for the GREEN LED and button events in app.h

 typedef enum APP_MsgId_T
 {
     APP_MSG_BLE_STACK_EVT,
     APP_MSG_ZB_STACK_EVT,
     APP_MSG_ZB_STACK_CB,
     APP_MSG_BLE_CS_LED_EVT,
     APP_MSG_BLE_CS_BUTTON_EVT,
     APP_MSG_STACK_END
 } APP_MsgId_T;

Add the custom service source and header files “<Harmony Content Path>\wireless_apps_pic32_bz6\apps\ble\building_blocks\peripheral\profiles_services\custom_service\firmware\src\app_ble_custom_service.c and app_ble_custom_service.h and app_ble_custom_service.h which has the supporting functions for the button LED custom service file.

Add the required variables, functions and callback handlers for the GATT read/write response in app_ble_handler.c along with the connect and disconnect message information.

void APP_BleGapEvtHandler(BLE_GAP_Event_T *p_event)
{ 
    switch(p_event->eventId)
    {
        case BLE_GAP_EVT_CONNECTED:
        {
        /* TODO: implement your application code.*/
        SYS_CONSOLE_PRINT("[BLE] Connected to Peer Device: 0x");
        for(int8_t idx=(GAP_MAX_BD_ADDRESS_LEN-1); idx>=0; idx--)
        {
            SYS_CONSOLE_PRINT("%02x", p_event->eventField.evtConnect.remoteAddr.addr[idx]);
        }
        SYS_CONSOLE_PRINT("\n\r[BLE] Connection Handle: %d\n\r",p_event->eventField.evtConnect.connHandle);
        G_ConnHandle = p_event->eventField.evtConnect.connHandle;
        }
        break;
        case BLE_GAP_EVT_DISCONNECTED:
        {
           /* TODO: implement your application code.*/
           SYS_CONSOLE_PRINT("[BLE] Disconnected Handle: %d, Reason: 0x%X\n\r",p_event->eventField.evtDisconnect.connHandle, p_event->eventField.evtDisconnect.reason);
           G_ConnHandle = 0;
           BLE_GAP_SetAdvEnable(0x01, 0); //Enable BLE Advertisement          
        }
        break;

Add the functions for the GATT read/write handlers which will act on the received GATT request in app_ble_handler.c.

void APP_GattSEvtReadHandler(GATT_EvtRead_T p_event)
{

    uint8_t error = 0;
    uint16_t status;
    SYS_CONSOLE_PRINT("[BLE] GATT Read ATTR Handle 0x%X \r\n",p_event.attrHandle);
    
    if ((p_event.attrHandle <= BUTTON_LED_START_HDL) ||
        (p_event.attrHandle > BUTTON_LED_END_HDL))
    {
        /* Not BLE Custom Service characteristic. */
        return;
    }

        switch(p_event.attrHandle)
        {
            case BUTTON_LED_HDL_CHAR_0:                            /**< Handle of characteristic 0. */
            case BUTTON_LED_HDL_CCCD_0:                            /**< Handle of characteristic 0 CCCD . */
            case BUTTON_LED_HDL_CHAR_1:                            /**< Handle of characteristic 1. */
            case BUTTON_LED_HDL_CHARVAL_1:                         /**< Handle of characteristic 1 value. */
                error = ATT_ERR_APPLICATION_ERROR;
                break;
            case BUTTON_LED_HDL_CHARVAL_0:                         /**< Handle of characteristic 0 value. */                
//                SYS_CONSOLE_PRINT(" ATTR Handle Read 0x%X \r\n",p_event.attrHandle);
                break;
        }

    if ((p_event.readType == ATT_READ_REQ)
    || (p_event.readType == ATT_READ_BLOB_REQ))
    {
        if (!error)
        {
            sp_trsReadRespParams = (GATTS_SendReadRespParams_T *)OSAL_Malloc(sizeof(GATTS_SendReadRespParams_T));
            if (sp_trsReadRespParams == NULL)
            {
                return;
            }
            trsRespErrConnHandle = p_event.connHandle;
            sp_trsReadRespParams->responseType = ATT_READ_RSP;
            sp_trsReadRespParams->attrLength = 0x01;
            sp_trsReadRespParams->attrValue[0]= bleCSdata.rgbOnOffStatus;            
            status = GATTS_SendReadResponse(p_event.connHandle, sp_trsReadRespParams);
            if (status == MBA_RES_SUCCESS)
            {
                OSAL_Free(sp_trsReadRespParams);
                sp_trsReadRespParams = NULL;
            }
        }
        else
        {
            sp_trsErrParams = (GATTS_SendErrRespParams_T *)OSAL_Malloc(sizeof(GATTS_SendErrRespParams_T));
            if (sp_trsErrParams == NULL)
            {
                return;
            }
            trsRespErrConnHandle = p_event.connHandle;
            sp_trsErrParams->reqOpcode = p_event.readType;
            sp_trsErrParams->attrHandle = p_event.attrHandle;
            sp_trsErrParams->errorCode = error;
            status = GATTS_SendErrorResponse(p_event.connHandle, sp_trsErrParams);
            if (status == MBA_RES_SUCCESS)
            {
                OSAL_Free(sp_trsErrParams);
                sp_trsErrParams = NULL;
            }
        }
    }   
}

void APP_GattSEvtWriteHandler(GATT_EvtWrite_T p_event)
{
    uint8_t error = 0;
    uint16_t status;
    SYS_CONSOLE_PRINT("[BLE] GATT Write ATTR Handle 0x%X \r\n",p_event.attrHandle);
    
    if ((p_event.attrHandle <= BUTTON_LED_START_HDL) ||
        (p_event.attrHandle > BUTTON_LED_END_HDL))
    {
        /* Not BLE Custom Service characteristic. */
        error = ATT_ERR_INVALID_HANDLE;
        return;
    }
    
        switch(p_event.attrHandle)
        {
            case BUTTON_LED_HDL_CHAR_0:                            /**< Handle of characteristic 0. */
            case BUTTON_LED_HDL_CHARVAL_0:                         /**< Handle of characteristic 0 value. */
            case BUTTON_LED_HDL_CCCD_0:                            /**< Handle of characteristic 0 CCCD . */
            case BUTTON_LED_HDL_CHAR_1:                            /**< Handle of characteristic 1. */
                error = ATT_ERR_APPLICATION_ERROR;
                break;
            case BUTTON_LED_HDL_CHARVAL_1:                         /**< Handle of characteristic 1 value. */
//                SYS_CONSOLE_PRINT(" ATTR Handle %d \r\n",p_event.attrHandle);
                APP_CustomService_RGB_Callback(p_event.writeValue);
                break;
        }

    if ((p_event.writeType == ATT_WRITE_REQ)
    || (p_event.writeType == ATT_PREPARE_WRITE_REQ))
    {
        if (!error)
        {
            sp_trsRespParams = (GATTS_SendWriteRespParams_T *)OSAL_Malloc(sizeof(GATTS_SendWriteRespParams_T));
            if (sp_trsRespParams == NULL)
            {
                return;
            }
            trsRespErrConnHandle = p_event.connHandle;
            sp_trsRespParams->responseType = ATT_WRITE_RSP;
            status = GATTS_SendWriteResponse(p_event.connHandle, sp_trsRespParams);
            if (status == MBA_RES_SUCCESS)
            {
                OSAL_Free(sp_trsRespParams);
                sp_trsRespParams = NULL;
            }
        }
        else
        {
            sp_trsErrParams = (GATTS_SendErrRespParams_T *)OSAL_Malloc(sizeof(GATTS_SendErrRespParams_T));
            if (sp_trsErrParams == NULL)
            {
                return;
            }
            trsRespErrConnHandle = p_event.connHandle;
            sp_trsErrParams->reqOpcode = p_event.writeType;
            sp_trsErrParams->attrHandle = p_event.attrHandle;
            sp_trsErrParams->errorCode = error;
            status = GATTS_SendErrorResponse(p_event.connHandle, sp_trsErrParams);
            if (status == MBA_RES_SUCCESS)
            {
                OSAL_Free(sp_trsErrParams);
                sp_trsErrParams = NULL;
            }
        }
    }
}