Step Climber Data (0x2ACF): byte layout
GATT characteristic · org.bluetooth.characteristic.step_climber_data · read from the Bluetooth SIG’s repository on 2026-10-17 · commit 408f4a0 (2026-10-14)
Step Climber Data is Bluetooth GATT characteristic 0x2ACF, org.bluetooth.characteristic.step_climber_data in the Bluetooth SIG's assigned numbers. The SIG's GATT Specification Supplement file lays its value out as 13 fields: Flags, Floors, Step Count, Steps Per Minute, Average Step Rate and 8 more. The first, Flags, is a boolean[16]; 12 of the others are present only when a bit of it is set as the field's text states, so after the first of those, a field's offset depends on which bits are set.
- UUID
- 0x2ACF
- Identifier
org.bluetooth.characteristic.step_climber_data- The SIG’s description
- The Step Climber Data characteristic is used to represent data related to a step climber device.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.step_climber_data.yaml
Byte layout: 13 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.
| Offset | Field | Type | Size | Present when | Unit |
|---|---|---|---|---|---|
| 0 | Flags | boolean[16] | 2 | Always (fixed size) | — |
| 2 | Floors | uint16 | 0 or 2 | Bit 0 of Flags is 0 | unitlessorg.bluetooth.unit.unitless |
| Depends on Flags (bit 0) | Step Count | uint16 | 0 or 2 | Bit 0 of Flags is 0 | unitlessorg.bluetooth.unit.unitless |
| Depends on Flags (bit 0) | Steps Per Minute | uint16 | 0 or 2 | Bit 1 of Flags is 1 | step (per minute)org.bluetooth.unit.step_per_minute |
| Depends on Flags (bits 0 and 1) | Average Step Rate | uint16 | 0 or 2 | Bit 2 of Flags is 1 | step (per minute)org.bluetooth.unit.step_per_minute |
| Depends on Flags (bits 0, 1 and 2) | Positive Elevation Gain | uint16 | 0 or 2 | Bit 3 of Flags is 1 | length (metre)org.bluetooth.unit.length.metre |
| Depends on Flags (bits 0, 1, 2 and 3) | Total Energy | uint16 | 0 or 2 | Bit 4 of Flags is 1 | energy (kilogram calorie)org.bluetooth.unit.energy.kilogram_calorie |
| Depends on Flags (bits 0, 1, 2, 3 and 4) | Energy Per Hour | uint16 | 0 or 2 | Bit 4 of Flags is 1 | energy (kilogram calorie)org.bluetooth.unit.energy.kilogram_calorie |
| Depends on Flags (bits 0, 1, 2, 3 and 4) | Energy Per Minute | uint8 | 0 or 1 | Bit 4 of Flags is 1 | energy (kilogram calorie)org.bluetooth.unit.energy.kilogram_calorie |
| Depends on Flags (bits 0, 1, 2, 3 and 4) | Heart Rate | uint8 | 0 or 1 | Bit 5 of Flags is 1 | period (beats per minute)org.bluetooth.unit.period.beats_per_minute |
| Depends on Flags (bits 0, 1, 2, 3, 4 and 5) | Metabolic Equivalent | uint8 | 0 or 1 | Bit 6 of Flags is 1 | metabolic equivalentorg.bluetooth.unit.metabolic_equivalent |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5 and 6) | Elapsed Time | uint16 | 0 or 2 | Bit 7 of Flags is 1 | time (second)org.bluetooth.unit.time.second |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5, 6 and 7) | Remaining Time | uint16 | 0 or 2 | Bit 8 of Flags is 1 | time (second)org.bluetooth.unit.time.second |
Field notes
Each field’s text in the SIG’s file, line by line.
- Flags boolean[16] · 2
- See Flags
- Floors uint16 · 0 or 2
- Unit: org.bluetooth.unit.unitlessThe Floors field represents the total number of floors counted by the Server since the beginning of the training session.Present if bit 0 of Flags field is set to 0
- Step Count uint16 · 0 or 2
- Unit: org.bluetooth.unit.unitlessThe Step Count field represents the total number of steps counted by the Server since the beginning of the training sessionPresent if bit 0 of Flags field is set to 0
- Steps Per Minute uint16 · 0 or 2
- Unit: org.bluetooth.unit.step_per_minuteThe Step per Minute Rate field represents the average step rate of a user during a period of one minute.Present if bit 1 of Flags field is set to 1
- Average Step Rate uint16 · 0 or 2
- Unit: org.bluetooth.unit.step_per_minuteThe Average Step Rate field represents the average step rate since the beginning of the training session.Present if bit 2 of Flags field is set to 1
- Positive Elevation Gain uint16 · 0 or 2
- Unit: org.bluetooth.unit.length.metreThe Positive Elevation Gain field represents the positive elevation gain since the beginning of the training session.Present if bit 3 of Flags field is set to 1
- Total Energy uint16 · 0 or 2
- Unit: org.bluetooth.unit.energy.kilogram_calorieThe Total Energy field represents the total expended energy of a user since the training session has started.Present if bit 4 of Flags field is set to 1
- Energy Per Hour uint16 · 0 or 2
- Unit: org.bluetooth.unit.energy.kilogram_calorieThe Energy per Hour field represents the average expended energy of a user during a period of one hour.Present if bit 4 of Flags field is set to 1
- Energy Per Minute uint8 · 0 or 1
- Unit: org.bluetooth.unit.energy.kilogram_calorieThe Energy per Minute field represents the average expended energy of a user during a period of one minute.Present if bit 4 of Flags field is set to 1
- Heart Rate uint8 · 0 or 1
- Unit: org.bluetooth.unit.period.beats_per_minuteThe Heart Rate field represents the current heart rate value of the user (e.g., measured via the contact heart rate or any other means).Present if bit 5 of Flags field is set to 1
- Metabolic Equivalent uint8 · 0 or 1
- Base Unit: org.bluetooth.unit.metabolic_equivalentRepresented values: M = 1, d = -1, b = 0Unit is 1/10 metabolic equivalentThe Metabolic Equivalent field represents the metabolic equivalent of the user.Present if bit 6 of Flags field is set to 1
- Elapsed Time uint16 · 0 or 2
- Unit: org.bluetooth.unit.time.secondThe Elapsed Time field represents the elapsed time of a training session since the training session has started.Present if bit 7 of Flags field is set to 1
- Remaining Time uint16 · 0 or 2
- Unit: org.bluetooth.unit.time.secondThe Remaining Time field represents the remaining time of a selected training session.Present if bit 8 of Flags field is set to 1
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.
Flags
The bits of this field are defined below.
| Bit | Description | Fields its condition names |
|---|---|---|
| 0 | More Data | Floors when 0Step Count when 0 |
| 1 | Steps Per Minute present | Steps Per Minute when 1 |
| 2 | Average Step Rate present | Average Step Rate when 1 |
| 3 | Positive Elevation Gain present | Positive Elevation Gain when 1 |
| 4 | Expended Energy present | Total Energy when 1Energy Per Hour when 1Energy Per Minute when 1 |
| 5 | Heart Rate present: | Heart Rate when 1 |
| 6 | Metabolic Equivalent present | Metabolic Equivalent when 1 |
| 7 | Elapsed Time present | Elapsed Time when 1 |
| 8 | Remaining Time present | Remaining Time when 1 |
| 9–15 | Reserved for Future Use | — |
Guides on this site
The connected-device guides that name 0x2ACF:
Questions
- What is the UUID of the Step Climber Data characteristic?
- 0x2ACF. The Bluetooth SIG's characteristic_uuids.yaml lists Step Climber Data as 0x2ACF with the identifier org.bluetooth.characteristic.step_climber_data. No file in the SIG's repository ties it to a service: the repository lists service and characteristic UUIDs separately.
- Which Step Climber Data fields are optional?
- 12 of its 13 fields have a published size that can be zero: Floors (0 or 2; Present if bit 0 of Flags field is set to 0); Step Count (0 or 2; Present if bit 0 of Flags field is set to 0); Steps Per Minute (0 or 2; Present if bit 1 of Flags field is set to 1); Average Step Rate (0 or 2; Present if bit 2 of Flags field is set to 1); Positive Elevation Gain (0 or 2; Present if bit 3 of Flags field is set to 1); Total Energy (0 or 2; Present if bit 4 of Flags field is set to 1); Energy Per Hour (0 or 2; Present if bit 4 of Flags field is set to 1); Energy Per Minute (0 or 1; Present if bit 4 of Flags field is set to 1); Heart Rate (0 or 1; Present if bit 5 of Flags field is set to 1); Metabolic Equivalent (0 or 1; Present if bit 6 of Flags field is set to 1); Elapsed Time (0 or 2; Present if bit 7 of Flags field is set to 1); Remaining Time (0 or 2; Present if bit 8 of Flags field is set to 1). Flags (2) has a fixed size.
- What units does Step Climber Data use?
- The SIG's text names a unit for 12 of the 13 fields: Floors: unitless (org.bluetooth.unit.unitless); Step Count: unitless (org.bluetooth.unit.unitless); Steps Per Minute: step (per minute) (org.bluetooth.unit.step_per_minute); Average Step Rate: step (per minute) (org.bluetooth.unit.step_per_minute); Positive Elevation Gain: length (metre) (org.bluetooth.unit.length.metre); Total Energy: energy (kilogram calorie) (org.bluetooth.unit.energy.kilogram_calorie); Energy Per Hour: energy (kilogram calorie) (org.bluetooth.unit.energy.kilogram_calorie); Energy Per Minute: energy (kilogram calorie) (org.bluetooth.unit.energy.kilogram_calorie); Heart Rate: period (beats per minute) (org.bluetooth.unit.period.beats_per_minute); Metabolic Equivalent: metabolic equivalent (org.bluetooth.unit.metabolic_equivalent); Elapsed Time: time (second) (org.bluetooth.unit.time.second); Remaining Time: time (second) (org.bluetooth.unit.time.second).
- What do the bits of the Step Climber Data Flags field mean?
- The SIG defines them as: bit 0, More Data (Floors when 0, Step Count when 0); bit 1, Steps Per Minute present (Steps Per Minute when 1); bit 2, Average Step Rate present (Average Step Rate when 1); bit 3, Positive Elevation Gain present (Positive Elevation Gain when 1); bit 4, Expended Energy present (Total Energy when 1, Energy Per Hour when 1, Energy Per Minute when 1); bit 5, Heart Rate present: (Heart Rate when 1); bit 6, Metabolic Equivalent present (Metabolic Equivalent when 1); bit 7, Elapsed Time present (Elapsed Time when 1); bit 8, Remaining Time present (Remaining Time when 1). The remaining bits are reserved for future use.
Source
Read on 2026-10-17 from gss/org.bluetooth.characteristic.step_climber_data.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.