3.8 Bluetooth® Low Energy Peripheral Transparent UART

This section helps users to create a peripheral device and send/receive characters between two connected BLE devices over Microchip proprietary Transparent UART Profile. Peripheral device will be the Curiosity board and central device can either be a Smart phone with Light Blue app or another Curiosity board.

Users can either choose to run the precompiled application example .hex file on the Curiosity board and experience the demo or go through the steps involved in developing this application from scratch.

Recommendation is to follow the examples in order, by learning the basic concepts first and then progressing to the more advanced topics.

Hardware Requirement

Table 3-15. Hardware Requirement
Tool	Qty
Curiosity Board	1
Micro USB cable	1
Android/iOS Smart phone	1

Software Requirement

MPLAB X IPE: For programming the precompiled hex file.
MPLAB X IDE: For programming the application example.
Teraterm: Terminal Emulator for displaying UART output.

Smart phone App

Light Blue iOS/Android app available in stores

Programming the Precompiled Hex File or Application Example

Programming the .hex File using MPLAB X IPE

Import and program the precompiled .hex file is located in “<Harmony Content Path>\wireless_apps_ble\apps\peripheral_trp_uart\hex\peripheral_trp_uart.hex” folder
For more information on the programming steps, refer to the Programming a Device in MPLAB IPE.
Note: Users must choose the correct device and tool information.

Programming the Application using MPLAB X IDE

Follow the steps mentioned in Running a Precompiled Example
Open and program the application example “peripheral_trp_uart_xxxx.X” where xxxx refer to device (for example: WBZ451, project file: peripheral_trp_uart_wbz451.X) located in “<Harmony Content Path>\wireless_apps_ble\apps\peripheral_trp_uart\firmware” using MPLAB X IDE

For more details on finding the Harmony content path, refer to Installing the MCC Plugin.

Demo Description

Refer BLE Transparent UART Peripheral Demo Description.

Developing the Application from Scratch Using MCC

This section explains the steps required by a user to develop this application example from scratch using MCC

Note: It is recommended that new users of MCC to go through the MPLAB® Code Configurator (MCC) User's Guide.

Create a new MCC Harmony Project by selecting the device. For more details, refer to Creating a New MCC Harmony Project.
Launch the MCC from the toolbar as illustrated below. The project graph will open with the default components.
Figure 3-84. MCC
In the Device Resources window, expand Libraries > Harmony > Wireless > Application Services. Then, click the Plus Symbol to add the Transparent App Service Component to the project
Figure 3-85. Transparent App Service
All BLE Transparent App Service-related components will be added into the project graph. Accept dependencies or satisfiers by selecting Yes.
For configuring BLE Config App Service component based on the device refer to Adding BLE Config App Service Component to Project Graph and Selecting the Device in Getting Started with WME Bluetooth Low Energy Applications from Related Links.
To enable digital and communication interfaces, refer to Enabling Digital Input/Output and Communication Interfaces Through System Hardware Definition (SHD) component in Getting Started with WME Bluetooth Low Energy Applications from Related Links.
For FreeRTOS component settings refer to the Configuring FreeRTOS in Getting Started with WME Bluetooth Low Energy Applications from Related Links.
Change the Transparent App Service component settings as illustrated in the following figure.
Figure 3-86. Transparent App Service
For WBZ451
1. Verify if the project graph window has all the expected components, as illustrated in the following figure:
  Figure 3-87. Project Graph
2. Verify FreeRTOS Component setting for Tick Mode and modify as illustrated in the following figure
  Figure 3-88. FreeRTOS
For WBZ351
1. Verify if the project graph window has all the expected components, as illustrated in the following figure:
  Figure 3-89. Project Graph
2. Verify FreeRTOS Component setting for Tick Mode and modify as illustrated in the following figure
  Figure 3-90. FreeRTOS
3. Verify SERCOM Component setting for Enable Run in Standby and modify as illustrated in the following figure
  Figure 3-91. SERCOM

Generating a Code

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

Files Containing User Application Code

Source code for the application will be generated from the MCC interface by clicking on Generate Code. User can add or edit the code in the highlighted files as illustrated in the following figure.

Details on files that user can modify

Table 3-16. Source Files
Source Files	Usage
`app.c`	Application State machine, includes calls for Initialization of all BLE stack (GAP,GATT, SMP, L2CAP) related component configurations
`app_ble_callbacks.c`	All the event functions related to GAP, GATT, SMP and L2CAP events that user can use or modify .
`app_trspc_callbacks.c`	All the event functions related to `trspc` event handles that user can use or modify.
`app_utility.c`	Contains generic utility functions that serve the purpose of providing reusable, common functionalities that can be applied across various parts of a program.

Note: app.c is auto generated and has a state machine based application code sample. Users can use this template to develop their application. Main application logic is implemented in void APP_Tasks() function.