Bluetooth GATT Characteristic Reference
HID Information (0x2A4A)
The HID Information Characteristic contains the HID attributes. The value of this Characteristic is static and can be cached for the lifetime of the bond between the HID device and the HID host.
Quick Summary
Payload length is 4 bytes. This page is generated from official GATT XML and presented as implementation-ready guidance.
At a Glance
Key reference details for BLE implementation, interoperability testing, and AI-assisted troubleshooting.
| Property | Value |
|---|---|
| Name | HID Information |
| UUID | 0x2A4A |
| Type | org.bluetooth.characteristic.hid_information |
| XML Root | Characteristic |
| Source File | org.bluetooth.characteristic.hid_information.xml |
| Field Count | 3 |
Field Specification
Parsed field definitions from the source XML value structure.
| Field | Requirement | Format | Unit | Exponent | Notes |
|---|---|---|---|---|---|
| bcdHID | Mandatory | uint16 | - | - | 16-bit unsigned integer representing version number of base USB HID Specification implemented by HID Device |
| bCountryCode | Mandatory | 8bit | - | - | Identifies which country the hardware is localized for. Most hardware is not localized and thus this value would be zero (0). |
| Flags | Mandatory | 8bit | - | - | - |
Bit Map
Bit-level enumerations extracted from the XML BitField definition.
| Field | Bit | Size | Name | 0 Means | 1 Means |
|---|---|---|---|---|---|
| Flags | 0 | 1 | RemoteWake | The device is not designed to be capable of providing wake-up signal to a HID host | The device is designed to be capable of providing wake-up signal to a HID host |
| Flags | 1 | 1 | NormallyConnectable | The device is not normally connectable | The device is normally connectable |
Byte Layout and Decode
Payload length is 4 bytes.
function decodePayload(dataView, offset = 0) {
const bcdhid = dataView.getUint16(offset + 0, true);
// Parse bcountrycode (8bit) according to Bluetooth format rules.
// Parse flags (8bit) according to Bluetooth format rules.
return { bcdhid, bcountrycode, flags };
}Use Cases and Integration Notes
BLE Telemetry
Map characteristic values into dashboards and alerts for device observability.
Firmware Regression
Compare decoded fields across builds to detect protocol or scaling changes.
App Integration
Build stable parsing paths that convert raw payloads into typed app models.
Implementation Checklist
- Validate payload length and mandatory fields before decode.
- Decode with Bluetooth-specified signedness, unit, and exponent handling.
- Convert units at presentation boundaries to avoid drift in business logic.
- Persist raw packets and decoded values for reproducible troubleshooting.
FAQ
What is HID Information in Bluetooth GATT?
HID Information is defined as a Bluetooth GATT characteristic entry with type org.bluetooth.characteristic.hid_information and UUID 0x2A4A.
What UUID identifies HID Information?
The UUID for HID Information is 0x2A4A.
How should I parse HID Information?
Payload length is 4 bytes.
Where does this definition come from?
This page is generated from the Bluetooth SIG mirror XML in the oesmith/gatt-xml repository.
How does this page support BLE implementation?
The page combines structured tables, practical Q&A, and JSON-LD metadata to help teams validate integrations and troubleshoot consistently.