STM32WBA Bluetooth® LE – P2P Router

1. Peer to Peer Router Topology

The Peer to Peer Router application is intended to demonstrate multi capabilities of the STM32WBA Bluetooth^® LE solution. It acts as:

• GAP Central & GATT Server (P2P Router Service) device to be connected and controlled by Smartphone
• GAP Peripheral & GATT Client device to control up to seven end devices (P2P Server)

The Peer to Peer Router service is a Generic Attribute Profile (GATT) based low-energy profile defined by STMicroelectronics with proprietary UUIDs(128 bits) including three characteristics

This wiki page is the description of the Peer to Peer Router project provided within the STM32CubeWBA MCU Package

Bluetooth® LE Peer to Peer Router & STM32WBA

The table below describes the structure of the P2P Router service:

Bluetooth® LE P2P Router Service specification
Service Characteristic Mode UUID size P2P Router Service 0000FEB0-cc7a-482a-984a-7f2ed5b3e58f Write forward Write without Response/Read 0000FEB1-8e22-4541-9d4c-21edae82ed19 2 Notif forward Notify 0000FEB2-8e22-4541-9d4c-21edae82ed19 2 LED Notify 0000FEB3-8e22-4541-9d4c-21edae82ed19 16

Health Thermometer is exported as a Service

• Temperature Measurement characteristic (TEMM):
  • send a temperature measurement, and update flags related to these.
• Temperature Type characteristic (MNBS):
  • is one of two methods that are used to describe the type of temperature measurement in relation to the location on the human body at which the temperature was measured.
• Intermediate Temperature characteristic (INT):
  • send intermediate temperature values to a device for display purposes while the measurement is in progress.
• Measurement Interval characteristic (MEI):
  • enables and controls the interval between consecutive temperature measurements.

Device Information (DIS) is exported as a Service

• Manufacturer Name String characteristic (MANS):
  • name of the manufacturer of the device.
• Model Number String characteristic (MONS):
  • model number assigned by the device vendor.
• System ID characteristic (SYID): 
  • structure containing an Organizationally Unique Identifier (OUI) followed by a manufacturer-defined identifier and is unique for each individual instance of the product.

Example of flow diagram between STM32WBA & ST BLE Toolbox

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 Health Thermometer Sensor example description

3.1. Project directory

The "BLE_HealthThermometer" application is available by downloading STM32CubeWBA MCU Package.

Heart Rate project directory

3.2. Project description

3.2.1. Structure

Software project structure with the most important parts:

Heart Rate project structure
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:

Heart Rate project initialization

Initialize the system (HAL, Clock, Power Mode, RTC IP, Timer Server) Infinite loop for run mode Initialize the BSP (LEDs, buttons…), Transport Layer Interface, Debugger Wait for initialization done Initialize the Bluetooth® LE App – GAP level Manage GAP events (advertising,scanning) Initialize the Bluetooth® LE App – GATT level Initialize the Bluetooth® LE Stack Manage GATT events Register Event Handler Initialize and manages services Update characteristic Initialize the context Manage Heart Rate Service notification

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