5.1.2.5 BLE Connection

This section explains how to enable advertisements and connection on the PIC32-BZ6 Curiosity board using the MPLAB Code Configurator (MCC). The peripheral device will be the PIC32-BZ6 Curiosity board and the central device can either be a smartphone with a Light Blue app or another PIC32-BZ6 Curiosity board. BLE Advertising is broadcasting small packets to peer devices. In BLE, a peripheral device always starts with advertisements. Advertisement packets enable a central or observer to discover and connect to a peripheral.

Users can choose to either run the precompiled Application Example hex file provided on the PIC32-BZ6 Curiosity Board or follow the steps to develop the application from scratch.

It is recommended to follow the examples in sequence to understand the basic concepts before progressing to the advanced topics.

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. FreeRTOS and BLE Stack Setup – See Peripheral - FreeRTOS BLE Stack and App Initialize from Related Links.

  4. See BLE Legacy Advertisements from Related Links.
  5. See BLE Connection from Related Links.

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

Hardware Requirement

Table 5-18. Hardware Prerequisites
S. No. Tool Quantity
1PIC32-BZ6 Curiosity Board1
2Micro USB cable1
3Android/iOS Smartphone1

SDK Setup

Refer to Getting Started with Software Development from Related Links.

Software Requirement

To install Tera Term tool, refer to the Tera Term web page in Reference Documentation from Related Links.

Smartphone App

Light Blue iOS/Android app available in stores

Programming the Precompiled Hex File or Application Example

Using MPLAB® X IPE:

  1. Import and program the precompiled hex file: <Harmony Content Path>\wireless_apps_pic32_bz6\apps\ble\building_blocks\peripheral\peripheral_conn\precompiled_hex\peripheral_conn.X.production.signed.hex.
  2. For detailed steps, refer to Programming a Device in MPLAB® IPE in Reference Documentation from Related Links.
    Note: Ensure to choose the correct Device and Tool information.

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\peripheral_conn\firmware\peripheral_conn.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 transmit Connectable and Scannable Undirected BLE Advertisements. On reset, demo will print “Advertising” on a terminal emulator like Tera Term which denotes the start of advertisements. The central device scanning these advertisements can then issue a connection request unto the Curiosity board. Upon connection, “Connected” is printed on the terminal window.

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 Tera Term:
    • Set the “Serial Port” to USB Serial Device.
    • Speed to 115200.
    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. “Advertising” must be displayed in Tera Term.
  5. Launch the Light Blue mobile app to scan for Advertisements. The device name “pic32cx-bz6” will appear then press Connect. After a successful connection, you can view the advertisement data and see “Connected” displayed in Tera Term. Users with an iOS device may see the device name as “Microchip”.
    Figure 5-81. 
    Note: Users can use another PIC32-BZ6 Curiosity board configured as BLE Connection (central) instead of using a mobile app. For more information, refer to BLE Connection from Related Links.

Developing the Application from Scratch using MCC

Follow the steps below to build the application manually:
Note: It is recommended for the new users of the MPLAB Code Configurator to refer MPLAB® Code Configurator (MCC) User’s Guide in Reference Documentation from Related Links.

  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\peripheral_conn\firmware\peripheral_conn.X\peripheral_conn.
    Note: Import and export functionality of Harmony component configuration will help users to start from a known working setup of MCC configuration.
  3. Accept dependencies or satisfiers when prompted.
  4. Verify if the project graph window has all the expected configuration.
Figure 5-82. Project Graph

Verifying Advertisement and Connection Configuration

  1. Select BLE Stack component in project graph, to open component configuration and configure as illustrated in the following figure.
    Figure 5-83. BLE Stack Configuration
    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).
    Figure 5-84. Configuration Panel
    .

Generating 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 MCC interface by clicking Generate Code, the BLE configuration source and header files can be found in the following project directories.
Figure 5-85. Project File

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.

Figure 5-86. initialization.c

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.

Figure 5-87. app_ble.c
Autogenerated, Advertisement Data Format
Figure 5-88. AD Structures and Types
Table 5-19. Source Files
Source Files Usage
app.cApplication State machine, includes calls for Initialization of all BLE stack (GAP,GATT, SMP, L2CAP) related component configurations
app_ble\app_ble.cSource code for the BLE stack related component configurations, code related to function calls from app.c
app_ble\app_ble_handler.cGAP, GATT, SMP and L2CAP event handlers
Note: app.c is autogenerated and has a state machine based application code. Users can use this template to develop their own application.

Header Files

  • ble_gap.h contains BLE GAP functions and is automatically included in app.c file.

Function Calls

  • MCC generates and adds the code to initialize the BLE Stack GAP, GATT, SMP and L2CAP in APP_BleStackInit()
  • APP_BleStackInit() is the API that will be called inside the Applications Initial State APP_STATE_INIT in app.c

User Application Development

Include

  • Include the user action. For more information, refer to User Action from Related Links.

  • definitions.h must be included in all the files where UART will be used to print debug information.

Note: definitions.h is not specific to UART but instead it must be included in all application source files where any peripheral functionality will be exercised.

Set Public Device Address in app_ble.c

  • BLE_GAP_SetDeviceAddr(&devAddr);
    BLE_GAP_Addr_T devAddr;
    devAddr.addrType = BLE_GAP_ADDR_TYPE_PUBLIC;
    devAddr.addr[0] = 0xA1;
    devAddr.addr[1] = 0xA2;
    devAddr.addr[2] = 0xA3;
    devAddr.addr[3] = 0xA4;
    devAddr.addr[4] = 0xA5;
    devAddr.addr[5] = 0xA6;

    // Configure device address
    BLE_GAP_SetDeviceAddr(&devAddr);
Figure 5-89. app_ble.c

Starting Advertisement in app.c.

BLE_GAP_SetAdvEnable(0x01, 0x00);
Figure 5-90. app.c

Connected and Disconnected Events

  • All the possible GAP, GATT, SMP and L2CAP Event handlers are available in file app_ble_handler.c. Users can implement their own application code to denote Connection State here.
    Figure 5-91. app_ble_handler.c
Note: Users can explore more BLE Advertisement functionalities using the BLE Stack APIs. For more information, refer to BLE Stack in Reference Documentation from Related Links.

Where to go from Here

See BLE Transparent UART from Related Links.