BLE API Reference

Every Sticky is an independent BLE peripheral exposing a role-specific GATT service — Sensing or Feedback — depending on which firmware it runs (see Stickies + Your Own Control Layer). You can build your own software against this API directly, without using the companion app.

Sensing service (0x0001)

Characteristic	UUID	Direction	Format
Capabilities	0x0001	Read	u8 flags (bit 0: tactile present)
IMU Data	0x0002	Notify	u8 sample_count; per sample: i16×3 accel, i16×3 gyro, u32 timestamp
Tactile Data	0x0005	Notify	u32 timestamp; u8[64] 8×8 pressure matrix
Config	0x0003	Write	u8 imu_rate_hz; u8 tactile_rate_hz
Echo	0x0004	Write / Notify	—

A sensing sticky automatically detects whether a tactile extension is attached at boot, so no manual device-type selection is needed. IMU streaming defaults to 100 Hz; tactile streaming defaults to 30 Hz, both reconfigurable via the Config characteristic.

Feedback service (0x0002)

Characteristic	UUID	Direction	Format
Motor Command (Stop)	0x0001	Write	u8 cmd = 0x00; u8 motor_id
Motor Command (Play)	0x0001	Write	u8 cmd = 0x01, u8 motor_id; u16 duration_ms, u8 count; u16 gap_ms, u8 intensity
Echo	0x0002	Write / Notify	—

Feedback firmware renders vibration patterns locally from a single Motor Command (Play) write — duration, repeat count, inter-pulse gap, and intensity are all specified in one command, so the host doesn't need to drive timing itself.

Notes

• Echo on both services is used for latency measurement (periodic echo request/response), not application data.
• Both services expose device identity over BLE so a host app can distinguish sensing vs. feedback stickies without manual selection.
• This API is deliberately raw/streaming — task semantics (metrics, calibration, feedback policies) are a host-side concern. See Reference Implementations for how the companion app builds on top of it.