Bluetooth GATT Characteristic Reference
Alert Category ID Bit Mask (0x2A42)
The value of the characteristic is a bit mask implemented as an array of unsigned 8 bit integers. The Alert Category ID Bit Mask characteristic defines one bit for each predefined category ID.
Quick Summary
Payload length is 2 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 | Alert Category ID Bit Mask |
| UUID | 0x2A42 |
| Type | org.bluetooth.characteristic.alert_category_id_bit_mask |
| XML Root | Characteristic |
| Source File | org.bluetooth.characteristic.alert_category_id_bit_mask.xml |
| Field Count | 2 |
Field Specification
Parsed field definitions from the source XML value structure.
| Field | Requirement | Format | Unit | Exponent | Notes |
|---|---|---|---|---|---|
| Category ID Bit Mask 0 | Mandatory | uint8 | - | - | - |
| Category ID Bit Mask 1 | Optional | uint8 | - | - | - |
Bit Map
Bit-level enumerations extracted from the XML BitField definition.
| Field | Bit | Size | Name | 0 Means | 1 Means |
|---|---|---|---|---|---|
| Category ID Bit Mask 0 | 0 | 1 | Simple Alert | Not Supported | Supported |
| Category ID Bit Mask 0 | 1 | 1 | Not Supported | Supported | |
| Category ID Bit Mask 0 | 2 | 1 | News | Not Supported | Supported |
| Category ID Bit Mask 0 | 3 | 1 | Call | Not Supported | Supported |
| Category ID Bit Mask 0 | 4 | 1 | Missed Call | Not Supported | Supported |
| Category ID Bit Mask 0 | 5 | 1 | SMS/MMS | Not Supported | Supported |
| Category ID Bit Mask 0 | 6 | 1 | Voice Mail | Not Supported | Supported |
| Category ID Bit Mask 0 | 7 | 1 | Schedule | Not Supported | Supported |
| Category ID Bit Mask 1 | 0 | 1 | High Prioritized Alert | Not Supported | Supported |
| Category ID Bit Mask 1 | 1 | 1 | Instant Message | Not Supported | Supported |
Byte Layout and Decode
Payload length is 2 bytes.
function decodePayload(dataView, offset = 0) {
const category_id_bit_mask_0 = dataView.getUint8(offset + 0);
const category_id_bit_mask_1 = dataView.getUint8(offset + 1);
return { category_id_bit_mask_0, category_id_bit_mask_1 };
}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 Alert Category ID Bit Mask in Bluetooth GATT?
Alert Category ID Bit Mask is defined as a Bluetooth GATT characteristic entry with type org.bluetooth.characteristic.alert_category_id_bit_mask and UUID 0x2A42.
What UUID identifies Alert Category ID Bit Mask?
The UUID for Alert Category ID Bit Mask is 0x2A42.
How should I parse Alert Category ID Bit Mask?
Payload length is 2 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.