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Your Chastity Lockbox uses multiple sensors to detect lock state and backplate position. This guide explains how the sensor system works and what the device monitors.

Sensor overview

Your device has two types of sensors:

TMR sensors (paddle detection)

Three TMR (Tunnel Magnetoresistance) sensors detect whether the locking paddle is in the locked or unlocked position.

How they work

  • Sensors detect the magnetic field from the paddle
  • When paddle is in locked position, sensors read LOW
  • When paddle is unlocked, sensors read HIGH

Detection logic

The device considers the paddle locked when:
Any two of three sensors detecting the locked position is sufficient. This provides redundancy—if one sensor fails, lock detection still works.

Why three sensors?

  • Redundancy: Two-of-three voting ensures reliable detection
  • Fault tolerance: Single sensor failure doesn’t break lock detection
  • Accuracy: Multiple sensors reduce false readings

Hall effect sensors (backplate detection)

Two Hall effect sensors detect whether the backplate is properly attached.

How they work

  • Sensors detect magnets embedded in the backplate
  • When backplate is attached, at least one sensor reads LOW
  • When backplate is removed, both sensors read HIGH

Detection logic

The device considers the backplate closed when:
Either sensor detecting the backplate magnet is sufficient.
The device will not allow locking if the backplate is not detected. This is a safety feature to prevent locking without proper closure.

Sensor verification during operations

Lock operation

When you initiate a lock:
  1. Motor drives paddle to lock position
  2. Device waits up to 2 seconds for paddle to reach position
  3. TMR sensors verify paddle is locked
  4. Hall sensors verify backplate is closed
  5. If all checks pass → Lock confirmed
  6. If checks fail → Error displayed

Unlock operation

When the device unlocks:
  1. Motor drives paddle to unlock position
  2. Device waits up to 2 seconds for paddle to move
  3. TMR sensors verify paddle is unlocked
  4. If check passes → Unlock confirmed
  5. If check fails → E-LOCK-2 error displayed

Error conditions

Most sensor errors are caused by physical obstruction. Check that nothing is blocking the paddle movement and that the backplate is properly seated.

Activity logging

When connected to WiFi, your device periodically reports sensor states to the dashboard:

Reported data

When logs are sent

  • On state changes (lock/unlock events)
  • On sensor state changes
  • Periodically during active sessions
This telemetry helps your keyholder monitor device status and allows support to diagnose issues remotely.

Current monitoring

An INA219 current sensor monitors motor current during lock/unlock operations:

Purpose

  • Detect when motor has completed movement
  • Prevent motor damage from stalling
  • Verify proper operation

Current limits

If average current exceeds 50mA for an extended period during motor operation, the motor stops automatically to prevent damage.

Sensor status in UI

The lock icon in the status bar reflects sensor state: See Status Symbols for detailed icon descriptions.

Troubleshooting sensor issues

The TMR sensors don’t detect the paddle in locked position. Check:
  • Nothing blocking the paddle
  • Backplate is properly seated
  • Try recalibrating if issue persists
The TMR sensors still detect the paddle as locked. Check:
  • Nothing preventing paddle movement
  • Device has sufficient battery
  • Contact support if motor sounds but paddle doesn’t move
The Hall sensors don’t detect the backplate. Check:
  • Backplate is fully seated and clicks into place
  • Clean contact area between device and backplate
  • Move away from strong magnetic sources
The backplate indicator shows yellow when Hall sensors don’t detect the backplate. Ensure the backplate is fully attached before locking.

Technical specifications

TMR sensors

Hall effect sensors

Current sensor (INA219)

Device Errors

Troubleshooting error codes.

Status Symbols

Understanding lock and backplate indicators.

Calibration

How calibration configures sensors.