STM32WBA Bluetooth® LE – Health Thermometer Project

1. Health Thermometer Profile

Health Thermometer Profile (HTP) is a Generic Attribute Profile (GATT) based low-energy profile defined by the Bluetooth^® Special Interest Group
Health Thermometer Profile is a combination of a Health Thermometer Collector and a Health Thermometer Sensor to connect and exchange data in different applications.
The Health Thermometer Sensor:

• Measures the temperature and exposes it via the Health Thermometer Service
• Contains the Device Information Service to be identified by the remote device
• Is the GATT server.

The Health Thermometer Collector:

• Accesses the information exposed by the Health Thermometer Sensor and can for example display it to the end user or store it on nonvolatile memory for later analysis.
• Is the GATT client.

This wiki page is the description of the Health Thermometer Sensor project provided within the STM32CubeWBA MCU Package

Bluetooth® LE Health Thermometer Profile & STM32WBA

The table below describes the structure of Health Thermometer Sensor services:

Bluetooth® LE Health Thermometer Service specification
Service Characteristic Property UUID size Health Thermometer Service 0x180D Temperature Measurement Indicate 0x2A1C 13 Temperature Type Read 0x2A1D 1 Intermediate Temperature Notify 0x2A1E 13 Measurement Interval Read,Write,Indicate 0x2A21 2 Device Information Service 0x180A Manufacturer Name String Read 0x2A29 32 Model Number String Read 0x2A24 32 System ID Read 0x2A29 8

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_HeartRate 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. Optimize low power

The project is delivered with the full system low-power enabled:

• no debug trace
• no debugger

The evaluation boards include the components to support the SMPS (switched mode power supply) integrated in microcontrollers.

• P-NUCLEO-WB55 pack including a USB dongle and a Nucleo-64 board with STM32WB55 MCU
• NUCLEO-WB15CC
• STM32WB5MM-DK Discovery

It is possible to enable the feature within app_ble.h

/**
 * SMPS supply
 * SMPS not used when Set to 0
 * SMPS used when Set to 1
 */
#define CFG_USE_SMPS    1

3.6. 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

4. Heart Rate Collector

4.1. ST BLE Sensor application - smartphones

Once the BLE Heart Rate application is installed on the STM32WB platform, launch the ST BLE Sensor smartphone application. Click on the interface Connect one Device. Then your device should be visible and connectable by clicking on it. Now bpm measurement is displayed in real time.

BLE Heart Rate application on ST BLE Sensor

4.2. ST BLE ToolBox application - smartphones

Once the BLE Heart Rate application is installed on the STM32WB platform, launch the ST BLE ToolBox smartphone application. The application starts scanning and allows to see advertisement data or to connect to the device. Once the device is connected bpm and kcal measurements are displayed in real time.

BLE Heart Rate application on ST BLE ToolBox

With the Discovery kit platform, the Heart Rate is also visible from the board LCD screen, and the heart pulse is illustrated below:

Heart Rate on DK illustration