Simple Peripheral

Table of Contents

Introduction

The simple_peripheral project implements a simple Bluetooth low energy peripheral device with GATT services and demonstrates the TI Simple Profile. This project can be a framework for developing many different peripheral-role applications. The Simple Peripheral project is used as the baseline for explaining the stack in the BLE5-Stack User's Guide.

This project has the following app configurations available:

App Build Configuration Description
FlashROM_Release (default) All TI-RTOS debug features disabled but application-logging to UART remains enabled.
The application uses the config file ble_release.cfg and the defines are in <app name>_FlashROM_Release.opt.
FlashROM_Debug All TI-RTOS debug features enabled.
The application uses the config file ble_debug.cfg and the defines are in <app name>_FlashROM_Debug.opt.
FlashROM_RCOSC_Release This is for a 32-kHz crystal-less device configuration.
All TI-RTOS debug features disabled but application-logging to UART remains enabled.
The application uses the config file ble_release.cfg and the defines are in <app name>_FlashROM_Release.opt.
This configuration is further discussed in the RCOSC section (Using 32-kHz Crystal-Less Mode) of the BLE5-Stack User's Guide.

All application configurations use the stack library configuration, FlashROM_Library. This build configuration will yield additional flash footprint optimizations by the linker since the application and stack can share contiguous flash pages. This configuration is further discussed in the Stack Library Configuration section of the BLE5-Stack User's Guide provided in the SDK.

Hardware Prerequisites

The default Simple Peripheral board configuration uses the device's LaunchPad development kit. This hardware configuration is shown in the below image:

For custom hardware, see the Running the SDK on Custom Boards section of the BLE5-Stack User's Guide.

Software Prerequisites

For information on what versions of Code Composer Studio and IAR Embedded Workbench to use, see the Release Notes file provided in the SDK. For information on how to import this project into your IDE workspace and build/run, please refer to the device's Platform section in the BLE5-Stack User's Guide.

Service/Profile Table

This project contains 1 service, which has 5 characteristics.

Note that BLE Scanner may report 128 bit UUIDs, but the project is generating 16 bit UUIDs.

Characteristic UUID Format Properties Profile Source
1 FFF1 1 Byte Integer Read/Write simple_peripheral.c/simple_gatt_profile.c
2 FFF2 1 Byte Integer Read simple_peripheral.c/simple_gatt_profile.c
3 FFF3 1 Byte Integer Write simple_peripheral.c/simple_gatt_profile.c
4 FFF4 1 Byte Integer Notify simple_peripheral.c/simple_gatt_profile.c
5 FFF5 5 Byte Integer Read simple_peripheral.c/simple_gatt_profile.c

Usage

This application uses the UART peripheral to provide an interface for the application. The UART is only used for display messages.

This document will use a terminal program (Tera Term, PuTTY, etc.) to serve as the display for the output of the LaunchPad, and it will use a BLE phone app, such as BLE Scanner (Android) or LightBlue Explorer (iOS), that will act as the central device that will connect to the Simple Peripheral device. This document will be using Tera Term and BLE Scanner. Note that any other serial terminal and smartphone BLE application can be used. The following default parameters are used for the UART peripheral for display:

UART Param Default Values
Baud Rate 115200
Data length 8 bits
Parity None
Stop bits 1 bit
Flow Control None

Once the Simple Peripheral sample application starts, the output to the terminal will report it's address and the fact that it is advertising. further more there is an option to set the peripheral to be a AutoConnect node as shown below:

Advertising is enabled by default upon startup, so there is no need to physically press a button to start advertising. if AutoConnect selected, the user will have to choose which group to be associated with Group A , Group B or Disable (none as default). Selecting a specific group will change the value of the Shortened local name (opcode 0x07) in the adv data. Group A will be set to GA Group B will be set to GB and the default if not setting any group or choosing Disable will be set to SP.

Using BLE Scanner to scan for the device, you should see a device with the name of SimplePeripheral (note that the navigation might be slightly different depending on your mobile application):

If there is more than 1 device called SimplePeripheral, the RSSI value in the colored circles on the left can be used to find which device you are trying to connect to. Press the "connect" button to connect to the device. Once connected, the terminal window will show the address of the connected device (smartphone):

After a connection is formed, you will also have the option to switch which physical layer (PHY) preference is used. Use the left button (BTN-1) to move to the next option and the right button (BTN-2) to select an option. For more information on the differences between the PHY options, see the PHY section of the BLE5-Stack User's Guide.

In BLE Scanner, you should be able to see various information about the Simple Peripheral device:

You should see 1 service, which is labeled as "CUSTOM SERVICE" (this may be slightly different for other smartphone applications). It will also provide its UUID. Clicking on this service will display the 5 characteristics that it contains, with information about each characteristic:

Scrolling down should show all 5 characteristics. The following sections detail the functions and operations of each of the characteristics.

Characteristic 1 (UUID: FFF1)

This characteristic demonstrates both read and write properties, and it contains a 1-byte-long value. As shown below, there are 2 circles, one with an "R" and one with a "W", next to "CUSTOM CHARACTERISTIC":

These are the buttons used for read and write operations. The value for this characteristic is set to "01" by default, and it can be changed by pressing the write button. Upon pressing the write button, you will see the following menu:

To write a new byte value to it, click on "Text" to change it to "Byte Array", and then enter the value that you want to write to the characteristic (in hexadecimal) in the field below. Press ok, and then you will be able to see that the value has changed by looking at the terminal window. The example below shows a write of 0x42 which is decimal for 66:

Note that the terminal window will print the value in decimal. The value will also be updated in BLE Scanner:

The read button can be used to read a value. If the Simple Peripheral device has changed the value of the characteristic (i.e. by using a button press), then pressing the read button will show the updated value in BLE scanner as shown above.

There is also a circle with an "R" next to "Characteristic User Description". Pressing this will show the name of the characteristic, as shown below:

Characteristic 2 (UUID: FFF2)

This characteristic has read property only. Its value can be read following the same procedure as is detailed for characteristic 1. It has a default value of 0x02.

Characteristic 3 (UUID: FFF3)

This characteristic has write property only. Its value can be written to following the same procedure as is detailed for characteristic 1. It has a default value of 0x03.

Characteristic 4 (UUID: FFF4)

This characteristic has notify property only. It is a single byte, and it is set to whatever value is contained in characteristic 3 (this value can be changed by writing to characteristic 3). Next to "CUSTOM CHARACTERISTIC" there is a circle with an "N". Pressing this button will enable notifications, and this characteristic will be updated and will display the value contained in characteristic 3: