STM32WBA Bluetooth® LE – P2P Router

Coming soon

1. Peer to Peer Router profile

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

• GAP Central & GATT Server (Router Service) device to be connected and controlled by a smartphone or a web page interface
• GAP Peripheral & GATT Client device to control up to seven end devices (P2P Server)

The 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

Overall application diagram

The table below describes the structure of Router service:

Bluetooth® LE Router Service specification
Service Characteristic Mode UUID Size 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 Device info Notify 0000FEB3-8e22-4541-9d4c-21edae82ed19 32

Router service is composed of three characteristics:

• Write forward characteristic :
  • to be used by the smartphone or web Bluetooth^® application to control one of the end device through the P2P router device.

Router service - Write forward characteristic
Byte Index 0 1 Name Index of end device LED level Value 0 to 13 0xFF: All 0x00: LED off 0x01: LED on

• Notify forward characteristic :
  • to be used by the P2P Router application to relay notification from end devices (button pushed) in order to inform smartphone or web Bluetooth^® application

Router service - Notify forward characteristic
Byte Index 0 1 Name Index of end device Switch level Value 0 to 13 0x00: Off 0x01: On

• Device info characteristic:
  • notifies end device information (BD address, Name, ..) to smartphone or web Bluetooth^® application

Router Service - Notify forward characteristic
Byte Index 0 1 [2:7] 8 9 [10:up to 31] Name Index of end device End device status End device BD address End device actual LED Level End device actual switch level End device advertising name Value 0 to 13 0x00: None 0x01: Found 0x02: Connecting 0x03: Discovering 0x04: Connected 0x05: Link lost BD address MSB to LSB 0x00: Off 0x01: On 0x00: Off 0x01: On ASCII string terminated by \0

Example of flow diagram between STM32WBAs & ST BLE Toolbox smartphone application.

1.1. Advertising data

At start up, P2P Router application starts advertising with an interval of approximatively 80-100ms.
Data advertised are composed as following:

Advertising packet
Description Length AD type Value Device Name 0x06 0x09 p2pR_XX as a string Manufacturer Data 0x0F 0xFF See table below Flags 0x02 0x01 0x06 (General discoverable, BrEdr not supported)

Manufacturer data are encoded following STMicroelectronics BlueST SDK v2 as described below:

Advertising manufacturer data STMicroelectronics BlueST SDK v2
Byte index 0 1 2-3 4 5 6 7 8 9 10-15 Function Length Manufacturer ID Company BlueST version Device ID Firmware ID Option 1 Option 2 Option 3 Bluetooth® Device address Value 0x0F 0xFF 0x0030 STMicro 0x02 0x8B Nucleo-WBA 0x85 P2P Router 0x00 0x00 0x00 0x00:80:E1:XX:XX:XX

1.2. On board buttons configuration

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 Starts scanning Starts scanning / / / / /

2. Requirements

2.1. Software and system requirements

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

• IAR Embedded Workbench for ARM (EWARM) toolchain V9.20.1, plus a patch available in WBA Firmware Package: STM32Cube_FW_WBA_Vx.x.x/Utilities/PC_Software/EWARMv8_STM32WBAx_V1.2.zip
• RealView Microcontroller Development Kit (MDK-ARM) toolchain V5.37, plus a patch available in WBA Firmware package: STM32Cube_FW_WBA_Vx.x.x/Utilities/PC_Software/Keil.STM32WBAx_DFP.1.0.0.zip
• STM32CubeIDE toolchain V1.12.0 .

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. Remote interfaces compatible

The STM32CubeWBA P2P Router project is compatible with the following remote interfaces:

• ST BLE ToolBox running on a smartphone or a tablet.
• Web Bluetooth^® interface running into a web browser.

3. STM32WBA P2P Router description

3.1. Project directory

The "BLE_p2pRouter" application is available by downloading STM32CubeWBA MCU Package.

Refer to How to Build a BLE Project wiki page for project directory information.

3.2. Project description

3.2.1. Structure

Software project structure with the most important parts:

P2P Router 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, peripherals) Infinite loop for run mode Initialize the BSP, power mode, trace, memory manager, NVM Wait for initialization done Initialize Bluetooth® LE Host Stack Initialize Bluetooth® LE GATT level Initialize Bluetooth® LE GAP level Reset registered handler count Initialize the context ManageP2P Router service notification Register service handler Update services and characteristics Initialize the context Register client event handler

3.2.3. GAP and GATT initialization and interaction

and The Bluetooth^® LE P2P Router application initialization is done within app_ble.c

• Initialize the BLE stack - initialize the device as peripheral and central - configure and start advertising - APP_BLE_init()
• Call the services controller initialization SVCCTL_Init() - svc_ctl.c
• Manage the GAP event - SVCCTL_App_Notification()
  • HCI_LE_CONNECTION_COMPLETE - provides information of the connection interval, slave latency, supervision timeout
  • HCI_LE_CONNECTION_UPDATE_COMPLETE- provides information of new connection
  • HCI_DISCONNECTION_COMPLETE - informs the application about the link disconnection and the reason

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

• Initialize the number of registered handler - SVCCTL_Init()
• Manage events - SVCCTL_UserEvtRx()- from the BLE Host Stack and redirect them to the gap event handler - SVCCTL_App_Notification

The application level of P2P Router is done with p2pr_app.c:

• Initialization of P2P Router service by calling P2PR_Init() - p2pr.c
• Initialization context of application applicative part:
  • Creation of some tasks
  • Setup data tables holding links status
• Receive notification from the P2P Router service - P2PR_Notification()

The P2P Router service p2pr.c manages the specification of the service:

• Service applicative part initialization - P2PR_Init()
  • Register P2P Router Event Handler to Service Controller - SVCCTL_RegisterSvcHandler(P2PR_EventHandler)
  • Initialize service, add P2P Router service as primary service
    • Initialize write forward (WRITEFWD) characteristic
    • Initialize notif forward (NOTIFFWD) characteristic
    • Initialize device info (DEVINFO) characteristic
• Manage the GATT event from BLE Stack - P2PR_EventHandler()
  • ACI_GATT_ATTRIBUTE_MODIFIED_VSEVT_CODE
    • Reception of an attribute modification packet
      • Update notification state for characteristics supporting it
      • Transfer packet to applicative part by calling P2PR_Notification() function

Client links are managed into file gatt_client_app.c

• Initialize the number of registered handler - SVCCTL_Init()
• Manage events - SVCCTL_UserEvtRx()- from the BLE Host Stack and redirect them to GATT client event handler - Event_Handler

Software module interaction

3.3. How to use

Once the BLE P2P Router application is installed on STM32WBA platform, launch ST BLE ToolBox smartphone or web Bluetooth^® application.
Then, scan and connect to device called p2pR_XX (where XX is replaced by the last byte of the BD address)
On release v1.0.0 total link count is limited to 8. Once the Bluetooth® LE connection is established and notifications are enabled by the smartphone:

• Pressing button 1 will allows to add an additional end device to P2P Router network by following steps:
  • Scan is started (blue LED turned on), reports are analysed, looking for a P2P Server application running around
  • Scan is stopped once a valid end device is found or scan timeout appends (blue LED turned off).
  • A valid end device is detected thanks to FW_ID present in advertising manufacturer data.
  • A connection is initiated and once done:
    • MTU configuration is exchanged - aci_gatt_exchange_config()
    • Services discovery is started - aci_gatt_disc_all_primary_services()
    • Then characteristics are discovered - aci_gatt_disc_all_char_of_service()
    • Then descriptors are discovered - aci_gatt_disc_all_char_desc()
    • For characteristics supporting notifications, there are enabled.

P2P Router application maintain tables containing information on connected end device referenced by a device index.
This device index can be from 0 to 13, see details below:

Table name a_P2PR_device_...	status[ ]	connHdl[ ]	bd_addr[ ]	char_write_level[ ]	char_notif_level[ ]	name[ ]	name_len[ ]
description	0x00: None 0x01: Found 0x02: Connecting 0x03: Discovering 0x04: Connected 0x05: Link lost	Connection handle	Bluetooth® Device Address	Level of write characteristic	Level of notification characteristic	Advertising name as a string	Advertising name string length

Updates of this table are sent to the remote interface by sending notifications on device info characteristic (format described in chapter 1).

3.4. 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

Initialization and remote interface connection phase
==>> 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:e1:2a:7e:05 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: aci_gatt_update_char_value - Device Name Success: aci_gatt_update_char_value - Appearance 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 Services and Characteristics creation Success: aci_gatt_add_service command: p2pR Success: aci_gatt_add_char command  : WRITEFWD Success: aci_gatt_add_char command  : NOTIFFWD Success: aci_gatt_add_char command  : DEVINFO End of Services and Characteristics creation Success: aci_hal_set_radio_activity_mask command ==>> aci_gap_set_discoverable - Success ==>> Success: Start Advertising >>== HCI_LE_CONNECTION_COMPLETE_SUBEVT_CODE - Connection handle: 0x0001 - Connection established with @:4f:5d:ff:57:3b:1e - Connection Interval: 30.00 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: 30.00 ms - Connection latency: 0 - Supervision Timeout: 5000 ms
Scan and connection to an end device
==>> aci_gap_start_general_discovery_proc - Success p2pServer name: p2pSext_F5, db addr: 0x00:80:E1:2A:7B:F5 -> stored into p2pRouter table at index 0 Success: aci_gatt_update_char_value DEVINFO command ==>> aci_gap_terminate_gap_proc - Success >>== ACI_GAP_PROC_COMPLETE_VSEVT_CODE -- GAP_GENERAL_DISCOVERY_PROC completed Create connection to p2pServer stored in table at index 0 wait for event HCI_LE_CONNECTION_COMPLETE_SUBEVT_CODE >>== ACI_GAP_PROC_COMPLETE_VSEVT_CODE >>== HCI_LE_CONNECTION_COMPLETE_SUBEVT_CODE - Connection handle: 0x0002 - Connection established with @:00:80:e1:2a:7b:f5 - Connection Interval: 50.00 ms - Connection latency: 0 - Supervision Timeout: 5000 ms Success: MTU exchange MTU exchanged size = 247 MTU exchanged size = 247 Discover services, characteristics and descriptors for table index 0 GATT services discovery ACI_ATT_READ_BY_GROUP_TYPE_RESP_VSEVT_CODE - ConnHdl=0x0002 1/2 short UUID=0x1801, handle [0x0001 - 0x0004], GENERIC_ATTRIBUTE_SERVICE_UUID found 2/2 short UUID=0x1800, handle [0x0005 - 0x000B], GAP_SERVICE_UUID found ACI_ATT_READ_BY_GROUP_TYPE_RESP_VSEVT_CODE - ConnHdl=0x0002 1/1 short UUID=0xFE40, handle [0x000C - 0x0011], P2P_SERVICE_UUID found PROC_GATT_DISC_ALL_PRIMARY_SERVICES services discovered Successfully DISCOVER_ALL_CHARS ConnHdl=0x0002 ALLServiceHandle[0x0001 - 0x0011] ACI_ATT_READ_BY_TYPE_RESP_VSEVT_CODE - ConnHdl=0x0002 ConnHdl=0x0002, number of value pair = 4 1/4 short UUID=0x2A05, Properties=0x0020, CharHandle [0x0002 - 0x0003], GATT SERVICE_CHANGED_CHARACTERISTIC_UUID charac found 2/4 short UUID=0x2A00, Properties=0x000A, CharHandle [0x0006 - 0x0007], GAP DEVICE_NAME charac found 3/4 short UUID=0x2A01, Properties=0x0002, CharHandle [0x0008 - 0x0009], GAP APPEARANCE charac found 4/4 short UUID=0x2A04, Properties=0x0002, CharHandle [0x000A - 0x000B] ACI_ATT_READ_BY_TYPE_RESP_VSEVT_CODE - ConnHdl=0x0002 ConnHdl=0x0002, number of value pair = 2 1/2 short UUID=0xFE41, Properties=0x0006, CharHandle [0x000D - 0x000E], ST_P2P_WRITE_CHAR_UUID charac found 2/2 short UUID=0xFE42, Properties=0x0010, CharHandle [0x000F - 0x0010], ST_P2P_NOTIFY_CHAR_UUID charac found All characteristics discovered Successfully DISCOVER_ALL_CHAR_DESCS [0x0001 - 0x0011] ACI_ATT_FIND_INFO_RESP_VSEVT_CODE - ConnHdl=0x0002 reset - UUID & handle - CHARACTERISTIC_UUID=0x2803 CharStartHandle=0x0002 UUID=0x2A05, handle=0x0003, found GATT SERVICE_CHANGED_CHARACTERISTIC_UUID Descriptor UUID=0x2902, handle=0x0002-0x0003-0x0004, Service Changed found PRIMARY_SERVICE_UUID=0x2800 handle=0x0005 reset - UUID & handle - CHARACTERISTIC_UUID=0x2803 CharStartHandle=0x0006 UUID=0x2A00, handle=0x0007, found GAP DEVICE_NAME_UUID reset - UUID & handle - CHARACTERISTIC_UUID=0x2803 CharStartHandle=0x0008 UUID=0x2A01, handle=0x0009, found GAP APPEARANCE_UUID reset - UUID & handle - CHARACTERISTIC_UUID=0x2803 CharStartHandle=0x000A UUID=0x2A04, handle=0x000B PRIMARY_SERVICE_UUID=0x2800 handle=0x000C reset - UUID & handle - CHARACTERISTIC_UUID=0x2803 CharStartHandle=0x000D ACI_ATT_FIND_INFO_RESP_VSEVT_CODE - ConnHdl=0x0002 UUID=0xFE41, handle=0x000E, found ST_P2P_WRITE_CHAR_UUID ACI_ATT_FIND_INFO_RESP_VSEVT_CODE - ConnHdl=0x0002 reset - UUID & handle - CHARACTERISTIC_UUID=0x2803 CharStartHandle=0x000F ACI_ATT_FIND_INFO_RESP_VSEVT_CODE - ConnHdl=0x0002 UUID=0xFE42, handle=0x0010, found ST_P2P_NOTIFY_CHAR_UUID ACI_ATT_FIND_INFO_RESP_VSEVT_CODE - ConnHdl=0x0002 Descriptor UUID=0x2902, handle=0x000F-0x0010-0x0011P2PNotification found : Desc UUID=0x2902 handle=0x000F-0x0010-0x0011 All characteristic descriptors discovered Successfully ServiceChangedCharDescHdl =0x0004 P2PNotificationDescHdl =0x0011 All notifications enabled Successfully Success: aci_gatt_update_char_value DEVINFO command