SC Control Point (0x2A55): byte layout
GATT characteristic · org.bluetooth.characteristic.sc_control_point · read from the Bluetooth SIG’s repository on 2026-10-17 · commit 408f4a0 (2026-10-14)
SC Control Point is Bluetooth GATT characteristic 0x2A55, org.bluetooth.characteristic.sc_control_point in the Bluetooth SIG's assigned numbers. The SIG's GATT Specification Supplement file lays its value out as 2 fields: Op Code and Parameter.
- UUID
- 0x2A55
- Identifier
org.bluetooth.characteristic.sc_control_point- The SIG’s description
- The SC Control Point characteristic is used to enable device-specific procedures related to a speed and cadence (SC) sensor.The structure of this characteristic is defined below.
- Service the SIG’s files tie it to
- None: no file in the repository lists this characteristic under a service.
- Source file
- gss/org.bluetooth.characteristic.sc_control_point.yaml
Byte layout: 2 fields
In the order the SIG’s structure lists them. Type and size are as published; sizes count octets except where a struct is marked as sized in bits. The offset is printed only where every earlier field has a fixed size; where an earlier field can be absent or vary, the cell names what it depends on. “Present when” is read from the field’s own “Present if” line, shown in full in the field notes below.
Field notes
Each field’s text in the SIG’s file, line by line.
- Op Code uint8 · 1
- See Op Code and Parameter
- Parameter struct · 0–18
- See Op Code and Parameter
Flags and value tables
The definitions the SIG’s file gives for its fields, every row as published. On a flags table the last column lists the fields whose “Present if” line names that bit.
Op Code and Parameter fields
The values of these fields are defined below.
| Op code | Definition | Parameter | Parameter type | Description |
|---|---|---|---|---|
| 0x00 | Reserved for Future Use | N/A | N/A | N/A |
| 0x01 | Set Cumulative Value | Cumulative Value as defined per service | Defined per service | Initiate the procedure to set a cumulative value. The new value is sent as parameter following op code (parameter defined per service).The response to this control point is Op Code 0x10 followed by the appropriate Response Value. |
| 0x02 | Start Sensor Calibration | N/A | N/A | Starts the calibration of the sensor.The response to this control point is Op Code 0x10 followed by the appropriate Response Value. |
| 0x03 | Update Sensor Location | Sensor Location Value (See Sensor Location in Sensor Location) | uint8 | Update to the location of the sensor with the value sent as parameter to this op code.The response to this control point is Op Code 0x10 followed by the appropriate Response Value. |
| 0x04 | Request Supported Sensor Locations | N/A | N/A | Request a list of supported locations for sensor attachment.The response to this control point is Op Code 0x10 followed by the appropriate Response Value, including a list of supported sensor locations (See Sensor Location (0x2A5D)) in the Response Parameter. |
| 0x05–0x0F | Reserved for Future Use | N/A | N/A | N/A |
| 0x10 | Response Code | Request Op Code, Response Code Value | N/A | See Response Code Values |
| 0x11–0xFF | Reserved for Future Use | N/A | N/A | N/A |
Response Code Values
The Response Code Values associated with the SC Control Point are defined below.
| Response code | Definition | Response parameter | Description |
|---|---|---|---|
| 0x00 | Reserved For Future Use | N/A | N/A |
| 0x01 | Success | Defined per service | Normal response for successful operation. |
| 0x02 | Op Code not supported | N/A | Response if unsupported Op Code is received |
| 0x03 | Invalid Operand | N/A | Response if Parameter received does not meet the requirements of the service. |
| 0x04 | Operation Failed | N/A | Response if the requested procedure failed. |
| 0x05–0xFF | Reserved for Future Use | N/A | N/A |
Guides on this site
No guide on this site names 0x2A55 yet. The connected-devices guides cover pairing, subscribing and testing for the device types they do name.
Questions
- What is the UUID of the SC Control Point characteristic?
- 0x2A55. The Bluetooth SIG's characteristic_uuids.yaml lists SC Control Point as 0x2A55 with the identifier org.bluetooth.characteristic.sc_control_point. No file in the SIG's repository ties it to a service: the repository lists service and characteristic UUIDs separately.
- Which SC Control Point fields are optional?
- 1 of its 2 fields has a published size that can be zero: Parameter (0–18; no “Present if” line in its text). Op Code (1) has a fixed size.
- Which values does the SC Control Point Op Code and Parameter table define?
- 0x01: Set Cumulative Value; 0x02: Start Sensor Calibration; 0x03: Update Sensor Location; 0x04: Request Supported Sensor Locations; 0x10: Response Code. The other rows are reserved for future use or carry no text.
Source
Read on 2026-10-17 from gss/org.bluetooth.characteristic.sc_control_point.yaml and assigned_numbers/uuids/characteristic_uuids.yaml in the Bluetooth SIG’s public repository (branch main, commit 408f4a0, committed 2026-10-14), by scripts/fetch-bluetooth-gatt.mjs. The file’s notice says it is proprietary to Bluetooth SIG, that furnishing it grants no licence, and that it is subject to change without notice; it is © Bluetooth SIG, Inc., and its text is quoted here for identification. Generated by AIFitnessAPI, which is not affiliated with Bluetooth SIG; the SIG’s file remains the authority. The full notice and the conventions used on these pages are on the reference hub.