STM32WB0 Bluetooth^® LE – human interface device

1. Human interface device over generic attribute profile↑

Human interface device over GATT profile (HOGP)^[1] is a low-energy profile, based on the generic attribute profile (GATT) defined by the Bluetooth^® special interest group (SIG)^[2]

This profile is an adaptation of the USB human interface device (HID) specification^[3] to operate over a Bluetooth^® LE wireless link. This profile operates on Bluetooth^® LE transport only.

The profile defines three roles:

The human interface device (HID) is a GATT server.
The boot host is a GATT client.
The report host is a GATT client.

Bluetooth^® LE devices are not supported by PC BIOS, because the Bluetooth^® LE stack and drivers are not loaded at this point yet, so the boot host role cannot be used with clients like PCs, smartphones, or tablets.

Bluetooth^® LE HOGP: report host and HID device

The report host supports the scan client role of the scan parameters profile.

The HID device has:

One or more instances of the HID service.
One or more instances of the battery service.
A single instance of the device information service.
Optionally, one instance of the scan parameters service as part of the scan server role of the scan parameters profile.
Optionally, a single or multiple instances of other services.

This wiki page describes the HID mouse and HID keyboard projects, provided with the STM32CubeWB0 MCU Package^[4]

Bluetooth^® LE HOGP mouse and keyboard profile with STM32WB0

The table below describes the structure of HOGP services:

Bluetooth^® LE HOGP profile specification

Service	Characteristic	Mode	UUID	Size
HID service			0x1812
	Input Report	Read/Write/Notify	0x2A4D	80
	Report Map	Read	0x2A4B	2
	HID information	Read	0x2A4A	4
	HID control point	Write without response	0x2A4C	1
Device information service			0x180A
	Manufacturer Name	Read	0x2A29	32
	Model Number	Read	0x2A24	32
	Firmware Revsion	Read	0x2A26	32
	Software Revsion	Read	0x2A28	32
	PnP ID	Read	0x2A50	7
Battery service			0x180F
	Battery level	Read/Notify	0x2A19	1
Scan Parameter service			0x1813
	Scan Interval Window	Write without response	0x2A4F	4
	Scan Refresh	Notify	0x2A31	1

The table below describes the HID report characteristic descriptors:

Bluetooth^® LE HID report characteristic descriptors specification

Characteristic name	Descriptor name	UUID	Size
Report		0x2A4D
	Client characteristic configuration descriptor	0x2902	1
	Report reference descriptor	0x2908	2

The table below describes the battery level characteristic descriptor:

Bluetooth^® LE battery level characteristic descriptor specification

Characteristic name	Descriptor name	UUID	Size
Battery level		0x2A19
	Client characteristic configuration descriptor	0x2902	1

The table below describes the Scan Refresh characteristic descriptors:

Bluetooth^® LE scan refresh characteristic descriptor specification

Characteristic name	Descriptor name	UUID	Size
Scan Refresh		0x2A19
	Client characteristic configuration descriptor	0x2902	1

HOGP is a combination of a HID device and a report host to connect and exchange data in different applications.

The generic access profile (GAP) defines and manages advertising and connection.

Report host central device and HID peripheral device

The generic attribute profile (GATT) defines and manages in/out data exchanges.

Report host GATT client device and HID GATT service device

Examples of an HID flow diagram between a STM32WB0 Serire board and a Bluetooth^® LE PC or Bluetooth^® LE smartphone

1.1. STMicroelectronics manufacturer advertising data↑

At startup, HID device application (mouse/keyboard) starts fast advertising (80ms/100ms), including the STMicroelectronics manufacturer advertising elements^[5] described below:

HID device STMicroelectronics manufacturer advertising data

	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
HID Device	0x0F	0xFF	0x0030 STMicro	0x02	0x8D Nucleo-WB0	0x8B	0x00	0x00	0x00	0x08E12Axxxx

Advertising is switched to low-power advertising (1s/2.5s) after 60 seconds.

2. Requirements↑

2.1. Software and Hardware requirements↑

For software and hardware requirements refer to STM32WB0 Build BLE Project wiki page.

2.2. Collector applications compatible↑

The STM32CubeWB0 HID mouse project is compatible with the following collectors:

The STM32CubeWB0 HID keyboard project is compatible with the following collectors:

3. HID Mouse device example description↑

3.1. Project directory↑

The "BLE_HID_Mouse" application is available by downloading the STM32CubeWB0 MCU Package^[6], in the following folder:

STM32Cube_FW_WB0_Vx.y.z\Projects\NUCLEO-WB05KZ\Applications\BLE\BLE_HID_Mouse
STM32Cube_FW_WB0_Vx.y.z\Projects\NUCLEO-WB07CC\Applications\BLE\BLE_HID_Mouse
STM32Cube_FW_WB0_Vx.y.z\Projects\NUCLEO-WB09KE\Applications\BLE\BLE_HID_Mouse

Refer to How to Build a Bluetooth® Low Energy project Wiki page for project directory information.

3.2. Project description↑

3.2.1. Structure↑

The figure below shows a software project structure, highlighting the most important parts:

HID mouse project structure

Main applicative part files

Service management

Bluetooth^® LE libraries

Bluetooth® LE stack modular configuration options and event dispatcher files

Warning

Do not modify the files in the middleware folder.

3.2.2. Application initialization↑

The figure below details the different steps of the application initialization.

HID mouse project initialization

Initialize the system (HAL, clocks, peripherals).

HAL_Init();
SystemClock_Config();
PeriphCommonClock_Config();
MX_GPIO_Init();
MX_RADIO_Init();
MX_RADIO_TIMER_Init();
MX_PKA_Init();
MX_APPE_Init();

Initialize the RNG, AES block, PKA:

HW_RNG_Init();
HW_AES_Init();
HW_PKA_Init();
APP_BLE_Init();

Initialize the Bluetooth^® LE Host Stack

BLE_Init();

Initialize the Bluetooth^® LE GATT level

Initialize the Bluetooth^® LE GAP level

Initialize the Application/Profile context (Services, Characteristics)

Manage the HID service notification.

Register Service Handler

Update services and characteristics

3.2.3. GAP and GATT initialization and interaction↑

The Bluetooth^® LE HID mouse application initialization is done within app_ble.c.

Initialize the Bluetooth^® LE stack, initialize the device as a peripheral, and configure and start advertising: ADV parameters, local name, and UUID - APP_BLE_init().
Call the services controller initialization BLEEVT_Init() - ble_evt.c.
Manage the GAP event - BLEEVT_App_Notification()
- HCI_LE_CONNECTION_COMPLETE_SUBEVT_CODE- provides information of the connection interval, slave latency, supervision timeout
- HCI_LE_CONNECTION_UPDATE_COMPLETE_SUBEVT_CODE- provides the new information of the connection
- HCI_DISCONNECTION_COMPLETE_EVT_CODE- informs the application about the link disconnection and the reason

Event management is done by the Bluetoooth® LE Event Dispatcher, ble_evt.c.

Initialize the number of registered handler - BLEEVT_Init()
Manage events - BLE_STACK_Event() - from the Bluetooth® LE Host Stack and redirect them to the event handler - BLEEVT_App_Notification

The application level of the HID mouse device is done with hids_app.c.

Initialization of the services:
- HID Service: HIDS_Init() in hids.c
Initialization of the context of the application:
- Report map
- HID information
Receive notifications from the HID service - HIDS_Notification().
When the remote enables the input report characteristic, it's possible to see the mouse pointer move in the display of paired computer or phone. This is a simulation of mouse movement: every 1 second the pointer moves on a fixed coordinate.

The HID service hids.c manages the specification of the service:

Service init (HIDS_Init()):
- Registers the HID event handle to the service controller: BLEEVT_RegisterGattEvtHandler(HIDS_EventHandler).
- Initializes the service UUID and adds the HID service as a primary service.
  - Initializes the report map characteristic.
  - Initializes the HID information characteristic.
Manages the GATT event from the Bluetooth^® LE stack (HIDS_EventHandler()).
- ACI_GATT_SRV_WRITE_VSEVT_CODE:
  - Reception of a write command: HID control point characteristic value.
    - Sending of an aci_gatt_srv_resp() with an OK or KO status.
    - Notification to the application to suspend or exit suspend (HIDS_Notification(HIDS_HCP_WRITE_NO_RESP_EVT)).
- ACI_GATT_SRV_ATTRIBUTE_MODIFIED_VSEVT_CODE:
  - Reception of an attribute modification - input report characteristics description value: enable or disable notification.
    - Notify application of the input report notification (HIDS_Notification(HIDS_INPUTREP_NOTIFY_ENABLED_EVT/HIDS_INPUTREP_NOTIFY_DISABLED_EVT)).

3.2.4. Report map and input report↑

HID report map characteristics should contain the USB HID descriptor, specified in the USB HID specification^[3].

A USB HID descriptor is a hard-coded array of bytes describing the data packets of the device, including:

The number of packets supported
The packet size
The purpose of each byte and bit in the packet

The figures below show an example of a USB mouse HID descriptor for a three-button mouse with X and Y axes and a wheel.

USB mouse HID descriptor

uint8_t reportDesc[] = {
  0x05, 0x01,        //USAGE_PAGE(Generic Desktop)
  0x09, 0x02,        //USAGE(Mouse)
  0xA1, 0x01,        //COLLECTION(Application)
  0x85, REPORT_ID,   // REPORT ID
  0x09, 0x01,        //USAGE(Pointer)
  0xA1, 0x00,        //COLLECTION(Physical)
  0x05, 0x09,        //USAGE_PAGE(Button)
  0x19, 0x01,        //USAGE_MINIMUM(Button 1)
  0x29, 0x03,        //USAGE_MAXIMUM(Button 3)
  0x15, 0x00,        //LOGICAL_MINIMUM(0)
  0x25, 0x01,        //LOGICAL_MAXIMUM(1)
  0x75, 0x01,        //REPORT_SIZE(1)
  0x95, 0x03,        //REPORT_COUNT(3)
  0x81, 0x02,        //INPUT(Data, Variable, Absolute) ; Button states
  0x75, 0x05,        //REPORT_SIZE(5)
  0x95, 0x01,        //REPORT_COUNT(1)
  0x81, 0x01,        //INPUT(Constant, Variable, Absolute) ; Reserved bits
  0x05, 0x01,        //USAGE_PAGE(Generic Desktop) 
  0x09, 0x30,        //USAGE(X)
  0x09, 0x31,        //USAGE(Y)
  0x16, 0x01, 0xF8,  //LOGICAL_MINIMUM(-2047)
  0x26, 0xFF, 0x07,  //LOGICAL_MAXIMUM(2047)
  0x75, 0x0C,        //REPORT_SIZE(12 bits)
  0x95, 0x02,        //REPORT_COUNT(2)
  0x81, 0x06,        //INPUT(Data, Variable, Relative) ; X & Y
  0x09, 0x38,        //USAGE(Z)
  0x15, 0x81,        //LOGICAL_MINIMUM(-127)
  0x25, 0x7F,        //LOGICAL_MAXIMUM(127)
  0x75, 0x08,        //REPORT_SIZE(8)
  0x95, 0x01,        //REPORT_COUNT(1)
  0x81, 0x06,        //INPUT(Data, Variable, Relative) ; Z
  0xC0,              //END_COLLECTION
  0xC0               //END_COLLECTION
};

Three-button mouse with X and Y axes and a wheel

All hard-coded bytes are described in the USB HID usage tables document^[7].This USB HID descriptor also defines the data structure sent in the associated reports (input, output, or feature).

In this USB mouse HID descriptor example, you can find:

Highlighted in green, the definition of three buttons represented by the first three bits of a byte that can have the boolean state 0 or 1. Bits 0, 1, and 2 represent the states of respectively the left, middle, and right buttons of the mouse. The remaining bits of the byte are unused.
Highlighted in blue, the definition of three bytes for the X and Y axes for relative movement and wheel rotation. Each byte represents a signed integer that can take a value comprised between -127 to 127.

The figure below shows an example of the input report associated with the USB mouse HID descriptor.

Data structure for a three-button mouse with X and Y axes and a wheel

3.3. How to use the Bluetooth^® LE HID mouse application↑

Once the Bluetooth^® LE HID mouse application is installed on the STM32WB0 nucleo board, launch a Bluetooth^® LE connection on a smartphone or a PC. Then, scan and connect the device called HID_XX (where XX is replaced by the last byte of the BD address) to the application.

3.3.1. Android Bluetooth^® LE HID mouse↑

Android Bluetooth^® LE HID mouse connection – How to

3.3.2. PC Bluetooth^® LE HID mouse↑

PC Bluetooth^® LE HID mouse – How to

PC Bluetooth^® LE HID mouse – How to

PC Bluetooth^® LE HID mouse – How to
	PC HID CONNECTED

PC Bluetooth^® LE HID mouse – How to

3.3.3. Bluetooth^® LE HID mouse how to↑

Once the Bluetooth® LE connection is established and the notification enabled by the smartphone or the PC, the HID input report is sent every 1 second and the smartphone or the PC pointer moves on a fixed coordinate (This is a simulation of mouse movement).

NUCLEO-WB05KZ/NUCLEO-WB07CC/NUCLEO-WB09KE are necessary to install the application.

Hardware platform illustration
NUCLEO-WB05KZ	NUCLEO-WB07CC	NUCLEO-WB09KE

3.4. Low-power optimization↑

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

Debug trace enabled
Debugger enabled, even in Low-power mode

It is possible to enable/disable the low-power feature within app_conf.h:

/******************************************************************************
 * Low Power
 *
 *  When CFG_FULL_LOW_POWER is set to 1, the system is configured in full
 *  low power mode. It means that all what can have an impact on the consumptions
 *  are powered down.(For instance LED, Access to Debugger, Etc.)
 *
 *  When CFG_LPM_SUPPORTED and CFG_FULL_LOW_EMULATED are both set to 1, the system is configured to
 *  emulate the Deepstop mode without losing the debugger connection and breakpoints nor watchpoints.
 *
 ******************************************************************************/

#define CFG_FULL_LOW_POWER       (0)

#define CFG_LPM_SUPPORTED        (0)

#define CFG_LPM_EMULATED         (0)

3.5. UART debug trace↑

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

To enable the traces within the project, enable them in app_conf.h as described below:

/*****************************************************************************
 * Traces
 * Enable or Disable traces in application
 * When CFG_DEBUG_TRACE is set, traces are activated
 *
 * Note : Refer to utilities_conf.h file in order to details
 *        the level of traces : CFG_DEBUG_TRACE_FULL or CFG_DEBUG_TRACE_LIGHT
 *****************************************************************************/
/**
 * Enable or disable debug prints.
 */
#define CFG_DEBUG_APP_TRACE             (1)

/**
 * Use or not advanced trace module. UART interrupts to be enabled.
 */
#define CFG_DEBUG_APP_ADV_TRACE         (0)

#define ADV_TRACE_TIMESTAMP_ENABLE      (0)

HID mouse - initialization phase

HID mouse - connected phase

 ==>> Start BLE_Init function
  Success: aci_hal_set_tx_power_level command
  Success: aci_gatt_srv_profile_init command
  Success: aci_gap_init command
  Static Random Bluetooth Address: e3:39:09:d2:dc:fb
  Success: Gap_profile_set_dev_name - Device Name
  Success: Gap_profile_set_appearance - Appearance
  Success: aci_gap_set_io_capability command
  Success: aci_gap_set_security_requirements command
  Success: aci_gap_configure_filter_accept_and_resolving_list command
==>> End BLE_Init function

Services and Characteristics creation
  Success: aci_gatt_srv_add_service command: HIDS
  Success: aci_gatt_srv_add_service command: DIS
  Success: aci_gatt_srv_add_service command: BAS
  Success: aci_gatt_srv_add_service command: SCPS
End of Services and Characteristics creation

==>> Success: aci_gap_set_advertising_configuration
==>> Success: aci_gap_set_advertising_data
==>> Success: aci_gap_set_advertising_enable

>>== hci_le_connection_complete_event - Connection handle: 0x0801
     - Connection established with @:7a:1b:79:e0:18:34
     - 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_EVENT: 0x08
>>== ACI_GAP_PAIRING_COMPLETE_VSEVT_CODE
     - Pairing Success

!!! Start virtual timer to update mouse coordinates!
HCI_VENDOR_EVT: 0x0C03
>>== HCI_LE_CONNECTION_UPDATE_COMPLETE_SUBEVT_CODE
     - Connection Interval:   48.75 ms
     - Connection latency:    0
     - Supervision Timeout:   5000 ms
Report Data: 0 - 32 - 0 - 0 - 0
  Success: aci_gatt_srv_notify INPUTREP command
Report Data: 0 - 0 - 20 - 3 - 0
  Success: aci_gatt_srv_notify INPUTREP command
Report Data: 0 - ce - f - 0 - 0
  Success: aci_gatt_srv_notify INPUTREP command
Report Data: 0 - 0 - e0 - fc - 0
  Success: aci_gatt_srv_notify INPUTREP command
Report Data: 0 - 32 - 0 - 0 - 0
  Success: aci_gatt_srv_notify INPUTREP command
Report Data: 0 - 0 - 20 - 3 - 0
  Success: aci_gatt_srv_notify INPUTREP command
Report Data: 0 - ce - f - 0 - 0
  Success: aci_gatt_srv_notify INPUTREP command
Report Data: 0 - 0 - e0 - fc - 0
  Success: aci_gatt_srv_notify INPUTREP command
Report Data: 0 - 32 - 0 - 0 - 0
  Success: aci_gatt_srv_notify INPUTREP command
Report Data: 0 - 0 - 20 - 3 - 0
  Success: aci_gatt_srv_notify INPUTREP command
Report Data: 0 - ce - f - 0 - 0
  Success: aci_gatt_srv_notify INPUTREP command
Report Data: 0 - 0 - e0 - fc - 0
  Success: aci_gatt_srv_notify INPUTREP command

4. HID Keyboard device example description↑

4.1. Project directory↑

The "BLE_HID_Keyboard" application is available by downloading the STM32CubeWB0 MCU Package^[6], in the following folder:

STM32Cube_FW_WB0_Vx.y.z\Projects\NUCLEO-WB05KZ\Applications\BLE\BLE_HID_Keyboard
STM32Cube_FW_WB0_Vx.y.z\Projects\NUCLEO-WB07CC\Applications\BLE\BLE_HID_Keyboard
STM32Cube_FW_WB0_Vx.y.z\Projects\NUCLEO-WB09KE\Applications\BLE\BLE_HID_Keyboard

Refer to How to Build a Bluetooth® LE project Wiki page for project directory information.

4.2. Project description↑

4.2.1. Structure↑

The figure below shows a software project structure, highlighting the most important parts:

HID Keyboard project structure

Main applicative part files

Service management

Bluetooth^® LE libraries

Bluetooth® LE stack modular configuration options and event dispatcher files

Warning

Do not modify the files in the middleware folder.

4.2.2. Application initialization↑

The figure below details the different steps of the application initialization.

HID Keyboard project initialization

Initialize the system (HAL, clocks, peripherals).

HAL_Init();
SystemClock_Config();
PeriphCommonClock_Config();
MX_GPIO_Init();
MX_RADIO_Init();
MX_RADIO_TIMER_Init();
MX_PKA_Init();
MX_APPE_Init();

Initialize the RNG, AES block, PKA:

HW_RNG_Init();
HW_AES_Init();
HW_PKA_Init();
APP_BLE_Init();

Initialize the Bluetooth^® LE Host Stack

BLE_Init();

Initialize the Bluetooth^® LE GATT level

Initialize the Bluetooth^® LE GAP level

Initialize the Application/Profile context (Services, Characteristics)

Manage the HID service notification.

Register Service Handler

Update services and characteristics

4.2.3. GAP and GATT initialization and interaction↑

The Bluetooth^® LE HID Keyboard application initialization is done within app_ble.c.

Initialize the Bluetooth^® LE stack, initialize the device as a peripheral, and configure and start advertising: ADV parameters, local name, and UUID - APP_BLE_init().
Call the services controller initialization BLEEVT_Init() - ble_evt.c.
Manage the GAP event - BLEEVT_App_Notification()
- HCI_LE_CONNECTION_COMPLETE_SUBEVT_CODE- provides information of the connection interval, slave latency, supervision timeout
- HCI_LE_CONNECTION_UPDATE_COMPLETE_SUBEVT_CODE- provides the new information of the connection
- HCI_DISCONNECTION_COMPLETE_EVT_CODE- informs the application about the link disconnection and the reason

Event management is done by the Bluetoooth® LE Event Dispatcher, ble_evt.c.

Initialize the number of registered handler - BLEEVT_Init()
Manage events - BLE_STACK_Event() - from the Bluetooth® LE Host Stack and redirect them to the event handler - BLEEVT_App_Notification

The application level of the HID mouse device is done with hids_app.c.

Initialization of the services:
- HID Service: HIDS_Init() in hids.c
Initialization of the context of the application:
- Report map
- HID information
Receive notifications from the HID service - HIDS_Notification().

The HID service hids.c manages the specification of the service:

Service init (HIDS_Init()):
- Registers the HID event handle to the service controller: BLEEVT_RegisterGattEvtHandler(HIDS_EventHandler).
- Initializes the service UUID and adds the HID service as a primary service.
  - Initializes the report map characteristic.
  - Initializes the HID information characteristic.
Manages the GATT event from the Bluetooth^® LE stack (HIDS_EventHandler()).
- ACI_GATT_SRV_WRITE_VSEVT_CODE:
  - Reception of a write command: HID control point characteristic value.
    - Sending of an aci_gatt_srv_resp() with an OK or KO status.
    - Notification to the application to suspend or exit suspend (HIDS_Notification(HIDS_HCP_WRITE_NO_RESP_EVT)).
- ACI_GATT_SRV_ATTRIBUTE_MODIFIED_VSEVT_CODE:
  - Reception of an attribute modification - input report characteristics description value: enable or disable notification.
    - Notify application of the input report notification (HIDS_Notification(HIDS_INPUTREP_NOTIFY_ENABLED_EVT/HIDS_INPUTREP_NOTIFY_DISABLED_EVT)).

4.2.4. Report map and input report↑

HID report map characteristics should contain the USB HID descriptor, specified in the USB HID specification^[3].

A USB HID descriptor is a hard-coded array of bytes describing the data packets of the device, including:

The number of packets supported
The packet size
The purpose of each byte and bit in the packet

The figures below show an example of a USB keyboard HID descriptor.

USB keyboard HID descriptor

uint8_t reportDesc[] = {
    0x05, 0x01,                 // Usage Page (Generic Desktop)        
	0x09, 0x06,                 // Usage (Keyboard)        
	0xA1, 0x01,                 // Collection (Application)        
	0x05, 0x07,                 //     Usage Page (Key Codes)        
	0x19, 0xe0,                 //     Usage Minimum (224)        
	0x29, 0xe7,                 //     Usage Maximum (231)        
	0x15, 0x00,                 //     Logical Minimum (0)        
	0x25, 0x01,                 //     Logical Maximum (1)        
	0x75, 0x01,                 //     Report Size (1)        
	0x95, 0x08,                 //     Report Count (8)        
	0x81, 0x02,                 //     Input (Data, Variable, Absolute)            
	0x95, 0x01,                 //     Report Count (1)        
	0x75, 0x08,                 //     Report Size (8)        
	0x81, 0x01,                 //     Input (Constant) reserved byte(1)            
	0x95, 0x05,                 //     Report Count (5)        
	0x75, 0x01,                 //     Report Size (1)        
	0x05, 0x08,                 //     Usage Page (Page# for LEDs)        
	0x19, 0x01,                 //     Usage Minimum (1)        
	0x29, 0x05,                 //     Usage Maximum (5)        
	0x91, 0x02,                 //     Output (Data, Variable, Absolute), Led report        
	0x95, 0x01,                 //     Report Count (1)        
	0x75, 0x03,                 //     Report Size (3)        
	0x91, 0x01,                 //     Output (Data, Variable, Absolute), Led report padding
	0x95, 0x06,                 //     Report Count (6)        
	0x75, 0x08,                 //     Report Size (8)        
	0x15, 0x00,                 //     Logical Minimum (0)        
	0x25, 0x65,                 //     Logical Maximum (101)        
	0x05, 0x07,                 //     Usage Page (Key codes)        
	0x19, 0x00,                 //     Usage Minimum (0)        
	0x29, 0x65,                 //     Usage Maximum (101)        
	0x81, 0x00,                 //     Input (Data, Array) Key array(6 bytes)            
	0x09, 0x05,                 //     Usage (Vendor Defined)        
	0x15, 0x00,                 //     Logical Minimum (0)        
	0x26, 0xFF, 0x00,           //     Logical Maximum (255)        
	0x75, 0x08,                 //     Report Count (2)        
	0x95, 0x02,                 //     Report Size (8 bit)        
	0xB1, 0x02,                 //     Feature (Data, Variable, Absolute)        
	0xC0                        // End Collection (Application)    
};

All hard-coded bytes are described in the USB HID usage tables document^[7]. This USB HID descriptor also defines the data structure sent in the associated reports (input, output, or feature).

4.3. How to use the Bluetooth^® LE HID keyboard application↑

Once the Bluetooth^® LE HID keyboard application is installed on the STM32WB0 nucleo board, launch a Bluetooth^® LE connection on a smartphone or a PC. Then, scan and connect the device called HID_XX (where XX is replaced by the last byte of the BD address) to the application.

4.3.1. Android Bluetooth^® LE HID keyboard↑

Android Bluetooth^® LE HID keyboard connection – How to

4.3.2. PC Bluetooth^® LE HID keyboard↑

PC Bluetooth^® LE HID keyboard – How to

PC Bluetooth^® LE HID keyboard – How to

PC Bluetooth^® LE HID keyboard – How to
	PC HID CONNECTED

PC Bluetooth^® LE HID keyboard – How to

4.3.3. Bluetooth^® LE HID keyboard how to↑

Once the Bluetooth® LE connection is established and the devices are bonded, it is possible to enter data using keyboard on serial terminal: each char is sent to peer device.