STM32WBA Bluetooth® LE – Peer 2 Peer Applications

1. Peer to Peer Profile

The Peer to Peer Profile is a Generic Attribute Profile (GATT) based low-energy profile defined by STMicroelectronics with proprietary UUIDs(128 bits)
The Peer to Peer Profile, widely used for direct connection, defines the communication between a GATT-server of a Peer to Peer Server device, and a GATT-client Collector device, such as a smartphone, STM32WBA Peer to Peer Client or Peer to Peer Router devices.

• The Peer to Peer Server:
  • Contains the P2P Service, which expose two characteristics (Notification & Write) in order to create a bi-direction data communication.
  • Is the GATT server.
• The Collector:
  • Accesses the information exposed by Peer to Peer Server, controls it with the Write characteristics, receives Notification from it.
  • Is the GATT client.

This wiki page is the description of the Peer to Peer Server and Peer to Peer Client projects provided within the STM32CubeWBA MCU Package

Follow this "link" for Peer to Peer Router project explanation.

Bluetooth® LE Peer to Peer Profile & STM32WBA

1.1. STM32WBA Peer to Peer Server application

The table below describes the structure of Peer to Peer service:

Bluetooth® LE Peer to Peer Service specification
Service Characteristic Mode UUID size P2P Service 0000FE40-cc7a-482a-984a-7f2ed5b3e58f LED Write without Response/Read 0000FE41-8e22-4541-9d4c-21edae82ed19 2 SWITCH Notify 0000FE42-8e22-4541-9d4c-21edae82ed19 2

Peer To Peer Server is exported as a Service

• LED characteristic:
  • Used to control LED1 (Blue) on STM32WBA platform by remote device .

Peer to Peer Service - LED Characteristic
Byte Index 0 1 Name LED Selection LED Level Value 0x01: blue LED 0x00: LEDoff 0x01: LEDon

• SWITCH Characteristic:
  • Used to switch LED or Lamp on Collector device.

Peer to Peer Service - SWITCH Characteristic
Byte Index 0 1 Name Button Selection Status Value 0x01: button1 0x00 or 0x01

Example of flow diagram between STM32WBA & ST BLE Toolbox

At start up, Peer To Peer Server application starts Advertising including the Manufacturer Advertising Elements as described below:

	0	1	2-3	4	5	6	7	8	9	10-15
	Length	Manufacturer ID	Company	BlueSTSDK Version	Device ID	Firmware ID	Option 1	Option 2	Option 3	Device Address
P2P Server	0x0F	0xFF	0x0030 STMicro	0x02	0x8B Nucleo-WBA	0x83	0x00	0x00	0x00	0x08E12Axxxx

Advertising is stopped after 30s, pressing B1 restart it.

1.2. STM32WBA Peer to Peer Client application

It acts as a Central device with the support of GATT Client Layer.
At start up, by pressing B1 button, Peer To Peer Client application:

• Starts scanning to detect Peer To Peer Sever application by filtering the Firmware ID of the STMicroelectronics Manufacturer advertising data
• Stops Scanning once P2P server detected
• Connects to the P2P Server to establish the connection.
• Discovers GATT Service & Characteristics of the P2P server
• Enable all GATT server notification characteristics

Once connected, the Peer To Peer Client application:

• by pressing B1 button, write a message to toggle the Blue LED of the P2P Server
• Receive notification to toggle the on board Blue LED from remote P2P Server Application.

Example of flow diagram between STM32WBA P2P Server & P2P Client

1.3. On board buttons configuration

P2P Applications Nucleo-WBA buttons configuration
Application Condition B1 Click B1 Long Press B2 Click B2 Long Press B3 Click B3 Long Press P2P Server Idle Connected Adv start Notification Clear Sec db Adv start (Multi conn) L2CAP CONN REQ P2P Client Idle Connected Start Scan Write Char Clear Sec db - Change Conn Int

2. Requirements

2.1. Software and system requirements

The software required are the following (minimum IDEs version):

• IAR Embedded Workbench for ARM (EWARM) toolchain V??
• RealView Microcontroller Development Kit (MDK-ARM) toolchain V??
• STM32CubeIDE toolchain V?? .

Programmer:

• STM32CubeProgrammer : To flash the board with an already generated binary

2.2. Hardware requirements

NUCLEO-WBA5 is necessary to install the application.

Hardware platform illustration

2.3. Collector applications compatible

The STM32CubeWBA Health Thermometer Sensor project is compatible with the following collector:

• ST BLE Sensor
• ST BLE ToolBox
• Web bluetooth interface

3. STM32WBA P2P Server & P2P Client examples description

3.1. Project directory

The "BLE_p2pserver" & "BLE_p2pclient"applications are available by downloading STM32CubeWBA MCU Package. LINK TO UPDATE

P2P Server & Client projects directory
File:Connectivity WBA P2Ps dir.png

3.2. Project description

3.2.1. Structure

Software project structure with the most important parts:

P2P Server / Client project structure
File:Connectivity WBA P2Ps Archi.png	File:Connectivity WBA P2Pc Archi.png Main applicative part files Bluetooth® LE Stack API Interface Services management System commands Transport Layer Interface WARNING: Do not modify the files in Middlewares folder

3.2.2. Application initialization

The different steps of the application initialization are described below:

P2P Server project initialization
Initialize the system (HAL, clocks, peripherals) Infinite loop for run mode Initialize the BSP, Power Mode, trace, memory manager, NVM Wait for initialization done Initialize the Bluetooth® LE Host Stack Initialize the Bluetooth® LE GATT level Initialize the Bluetooth® LE GAP level Reset the number of registered handler Initialize the context Manage Heart Rate Service notification Register Service Handler Update services and characteristics
P2P Client project initialization
Initialize the system (HAL, clocks, peripherals) Infinite loop for run mode Initialize the BSP, Power Mode, trace, memory manager, NVM Wait for initialization done Initialize the Bluetooth® LE Host Stack Initialize the Bluetooth® LE GATT level Initialize the Bluetooth® LE GAP level Reset the number of registered handler Initialize the context Register Client Handler

3.2.3. GAP and GATT initialization and interaction

The Bluetooth LE Heart Rate Sensor application initialization is done within app_ble.c

• Start the BLE stack - initialize the device as peripheral - configure and start advertising: ADV parameters, local name, UUID - APP_BLE_init()
• Call the services controller initialization SVCCTL_Init() - svc_ctl.c
• Manage the GAP event - SVCCTL_App_Notification()
  • EVT_LE_CONN_COMPLETE - provides information of the connection interval, slave latency, supervision timeout
  • EVT_LE_CONN_UPDATE_COMPLETE - provides the new information of the connection
  • EVT_DISCONN_COMPLETE - informs the application about the link disconnection and the reason
  • EVT_ENCRYPT_CHANGE - informs the application weather the link is encrypted

The Services management is done by the service controller - svc_ctl.c

• Call the Initialization function of all the developed services - SVCCTL_SvcInit()
  • Heart Rate Service - HRS_Init() - hrs.c
  • Device Information service - DIS_Init() - dis.c
• Register Services Event Handler - SVCCTL_RegisterSvcHandler(...)
• Manage events - SVCCTL_UserEvtRx ()- from the BLE Host Stack and redirect them to the services registered - HearRate_Event_Handler() - or gap event handler - SVCCTL_App_Notification

The Heart Rate Service hrs.c manages the specification of the service:

• Service Init - HRS_Init()
  • Register Heart Rate Event Handle to Service Controller - SVCCTL_RegisterSvcHandler(HearRate_Event_Handler);
  • Initialize Service UUID – add Heart Rate service as Primary services
    • Initialize Heart rate measurement characteristic
    • Initialize Body Sensor location characteristic
• Update Heart Rate measurement characteristic - HRS_UpdateChar()
• Update Body Sensor location characteristic Value - HRS_UpdateChar()
• Manage the GATT event from BLE Stack - HeartRate_Event_Handler()
  • ACI_GATT_WRITE_PERMIT_REQ_VSEVT_CODE
    • Reception of a Write Command: HR Control Point Characterictic Value
      • Send an aci_gatt_write_response() with an OK or KO status.
      • Notify the application to Reset Energy Expended - HRS_Notification(HRS_RESET_ENERGY_EXPENDED_EVT)
  • ACI_GATT_ATTRIBUTE_MODIFIED_VSEVT_CODE
    • Reception of an attribute modification - HR Measurement Characteristics Description Value : ENABLE or DISABLE Notification
      • Notify application of the Measurement Notification - HRS_Notification(HRS_NOTIFICATION_ENABLED/DISABLED)

Heart Rate Sensor software module interaction

The application level of the Heart Rate Sensor is done with hrs_app.c:

• Initialization of the context of the application
  • Measurement value flags support
  • Body sensor location - HRS_BODY_SENSOR_LOCATION_HAND
• Receive notification from the Heart Rate Service - HRS_Notification()
• When Heart rate measurement characteristics are enabled by the remote, simulate every 1 s the Heart Rate Measure (HRSAPP_Measurement) and increase the energy expended to transfer to the remote device (collector) - HRS_UpdateChar()

3.3. Build and install

Follow the steps described in Bluetooth^® LE Build and Install Application page, applying them for STM32WBA BLE_HealthThermometer project.

3.4. How to use

Once the BLE Heart Rate application is installed on the STM32WB platform, launch ST BLE Sensor or ST BLE ToolBox smartphone application. Then, scan and connect the device called HRSTM to the application.
Once the Bluetooth® LE connection is established and the notification enabled by the smartphone:

• Heart Rate measurement is provided to remote every 1 s.
  • thanks to the timer server and the task manager

BLE Heart Rate application support the pairing procedure

• SW1 allows to clear the security database
• SW2 allows to request pairing

With the WB55.Nucleo board, it is possible to change RF PHY modulation

• SW3 allows to switch to 2 Mbits or 1 Mbits PHY

3.5. UART debug trace

Thanks to the debug log via UART interface, it is possible to trace the application project.

To enable the traces within the project, enable them within app_ble.c as described below:

/**
 * When set to 1, the traces are enabled in the BLE services
 */
#define CFG_DEBUG_BLE_TRACE     1
/**
 * Enable or Disable traces in application
 */
#define CFG_DEBUG_APP_TRACE     1

Heart Rate Sensor - Initialization phase

Connected Phase

Wireless Firmware version 1.13.0 Wireless Firmware build 5 FUS version 1.2.0 >>== SHCI_SUB_EVT_CODE_READY >>== WIRELESS_FW_RUNNING >>== DBGMCU_GetRevisionID= 2001 ==>> Start Ble_Hci_Gap_Gatt_Init function Success: hci_reset command Success: aci_hal_write_config_data command - CONFIG_DATA_PUBADDR_OFFSET Public Bluetooth Address: 00:80:e1:26:ff:eb Success: aci_hal_write_config_data command - CONFIG_DATA_IR_OFFSET Success: aci_hal_write_config_data command - CONFIG_DATA_ER_OFFSET Success: aci_hal_set_tx_power_level command Success: aci_gatt_init command Success: aci_gap_init command Success: hci_le_set_default_phy command Success: aci_gap_set_io_capability command Success: aci_gap_set_authentication_requirement command Success: aci_gap_configure_whitelist command ==>> End Ble_Hci_Gap_Gatt_Init function Device Information Service (DIS) is added Successfully 000C Manufacturer Name Characteristic Added Successfully 000D Model Number String Characteristic Added Successfully 000F Heart Rate Service (HRS) is added Successfully 0011 Heart Rate Measurement Characteristic Added Successfully 0012 Sensor Location Characteristic Added Successfully 0015 Control Point Characteristic Added Successfully 0017 ==>> aci_gap_set_discoverable - Success ==>> Success: Start Fast Advertising

>>== HCI_LE_CONNECTION_COMPLETE_SUBEVT_CODE - Connection handle: 0x801 - Connection established with Central: @:72:16:9d:9e:d5:8e - Connection Interval: 48.75 ms - Connection latency: 0 - Supervision Timeout: 5000 ms >>== HCI_LE_CONNECTION_UPDATE_COMPLETE_SUBEVT_CODE - Connection Interval: 7.50 ms - Connection latency: 0 - Supervision Timeout: 5000 ms >>== HCI_LE_CONNECTION_UPDATE_COMPLETE_SUBEVT_CODE - Connection Interval: 48.75 ms - Connection latency: 0 - Supervision Timeout: 5000 ms ACI_GATT_ATTRIBUTE_MODIFIED_VSEVT_CODE HRS_NOTIFICATION_ENABLED ==>> hci_le_read_phy - Success ==>> PHY Param TX= 1, RX= 1 ==>> hci_le_set_phy PHY Param TX= 2, RX= 2 - Success ==>> HCI_LE_PHY_UPDATE_COMPLETE_SUBEVT_CODE - status ok ==>> hci_le_read_phy - Success ==>> PHY Param TX= 2, RX= 2