visionos-esp32-sensor-bridge

Overview

Firmware for ESP32 that reads BNO055 orientation (roll, pitch, yaw) and ThinPot analog depth, applies motion-aware filtering (median for spikes, raw while moving, heavy Kalman + EMA + SMA when stationary), and streams telemetry over BLE for VisionOS/VR clients.

Features

• Sensors: Adafruit BNO055 + ThinPot.
• Adaptive filtering:
  • Median filter (window=5) to de-spike input.
  • Motion detection via recent variation.
  • While moving → raw values for responsiveness.
  • When stationary → Kalman + exponential smoothing (α=0.02) + 10-sample moving average.
  • Auto-reset of filter state at motion→stationary transition to prevent lag.
• BLE telemetry: NimBLE-based server with notifications at 10 Hz (delay(100)).

BLE

• Service UUID: "180C"
• Characteristic UUID: "2A56" (notify + read)
• Payload (CSV): roll_deg,pitch_deg,yaw_deg,depth_mm
  Example: 12.34,-1.02,178.90,57.3

Build & Dependencies

• Board: ESP32 Nano
• Baud: 115200
• Libraries:
  • Adafruit_BNO055
  • Adafruit Unified Sensor
  • NimBLE-Arduino
• Notes: bno.setExtCrystalUse(true) enabled.

Calibration

On boot, you’ll see a prompt; place the sensor in the desired starting orientation. After ~3 s, the code captures zero offsets (setZero()).

Tuning

Key parameters near the top of the sketch:

• MOTION_THRESHOLD (mm), MOTION_SAMPLES
• MEDIAN_WINDOW
• Stationary filter: Q, R, alpha, and STATIONARY_THRESHOLD

Wiring (typical)

• BNO055: SDA → ESP32 SDA, SCL → ESP32 SCL, 3V3, GND
• ThinPot: Wiper → THINPOT_PIN (ADC), ends to 3V3 and GND

Output Rate

~10 Hz notifications (adjust delay(100)).

Use Cases

• VisionOS / VR dashboards
• Haptics/robot control panels that need stable depth at rest and low-latency motion updates