Support & FAQ

Just Sensors is an iOS app that lets you explore 27+ sensors on your iPhone with real-time visualizations. You can view live data, record sessions, export to CSV or JSON, stream via MQTT, and use the Apple Watch companion. Experimental features include Acoustic Sonar, Doppler Velocity, and Metal Detector.

Just Sensors requires iOS 16.0 or later and works on all iPhones that support iOS 16. However, some sensors are only available on specific models:

• LiDAR Scanner: iPhone 12 Pro and later Pro models
• Face Tracking: iPhone X and later (requires TrueDepth camera)
• NFC Reader: iPhone 7 and later
• Barometer: iPhone 6 and later

Just Sensors offers a free tier that includes access to all 27+ sensors with real-time visualizations — no ads, no account required.

Coming soon: We're working on optional Pro features available as a one-time in-app purchase:

• Unlimited recording sessions
• Extended recording duration
• Advanced export options

The core sensor exploration experience will always remain free.

Not all sensors are available on all iPhone models. The app shows a green indicator for available sensors and a red indicator for unavailable ones.

Common reasons for unavailability:

• LiDAR: Only on Pro models (iPhone 12 Pro+)
• Face Tracking: Requires TrueDepth camera
• Certain motion sensors: May be disabled in Accessibility settings

Some sensors require explicit permission. To grant access:

• Open Settings on your iPhone
• Scroll down and tap Just Sensors
• Enable the required permissions (Location, Camera, Microphone, etc.)

You can also tap the gear icon in the app to see permission status and quickly access Settings.

Just Sensors displays raw data directly from your device's hardware sensors. Accuracy depends on your specific iPhone model and its sensor calibration.

The app is designed for educational and informational purposes. For applications requiring precise measurements, professional calibrated instruments should be used.

The Bluetooth scanner detects nearby Bluetooth Low Energy (BLE) devices and shows:

• Device name (if advertised)
• Signal strength in dBm
• Estimated distance based on signal
• Manufacturer information
• UUID and connection status

The Device Finder feature lets you track a specific device's distance with a radar-style visualization. The app also supports iBeacon scanning — switch to the iBeacons tab to scan for registered iBeacon devices.

Note: This feature only detects Bluetooth Low Energy (BLE) devices. Classic Bluetooth devices (like older headphones or speakers) are not supported due to iOS platform limitations.

Face Tracking uses Apple's TrueDepth camera (the same hardware used for Face ID) to detect and visualize facial expressions in real-time.

What it shows:

• A real-time mesh overlay of your face
• 52 blend shape values (smile, blink, eyebrow raise, etc.)
• Head position and rotation

Privacy note: Face data is processed entirely on your device and is never stored, saved, or transmitted anywhere. When you leave the Face Tracking screen, all data is immediately discarded. See our Privacy Policy for full details.

These features require specific hardware:

• Face Tracking: Requires TrueDepth camera (iPhone X and later with Face ID, or iPad Pro with Face ID). iPhone SE models do not have TrueDepth.
• LiDAR: Requires LiDAR scanner (iPhone 12 Pro and later Pro models, or iPad Pro 2020 and later).

If your device doesn't have the required hardware, the AR Sensors section will appear grayed out with a message explaining why.

To scan an NFC tag:

• Open Just Sensors and scroll to "Radio"
• Tap "NFC Reader"
• Tap the "Scan NFC Tag" button
• Hold the top of your iPhone near an NFC tag
• The tag data will appear on screen

Tips:

• The NFC antenna is at the top of the iPhone
• Hold steady for 1-2 seconds
• Works with NDEF-formatted tags
• Requires iPhone 7 or later

MQTT Export lets you stream live sensor data to any MQTT broker (e.g. Home Assistant, Grafana, Mosquitto). Data is published as you collect it, so you can build dashboards or automate based on sensor values.

To set up:

• Open the app → tap the gear icon (Settings)
• Under Data Export, tap MQTT Export
• Enter your broker host, port, optional username/password, and base topic
• Start a sensor and tap the MQTT/stream button to begin publishing

See our MQTT Integration Guide for topic format, examples, and Home Assistant configuration.

Spatial Radar uses Ultra-Wideband (UWB) to measure precise distance and direction between two devices. It only works as a peer-to-peer demo between two iPhones (iPhone 11 or later) both running Just Sensors with the UWB screen open.

It cannot detect AirTags, HomePods, or other UWB devices — Apple restricts those to their own apps. If you see a network error, check Settings → Privacy & Security → Local Network and ensure Just Sensors is allowed.

Experimental features are optional and can be toggled in Settings → Beta Features → Experimental Features.

• Acoustic Sonar: Uses near-ultrasonic frequency sweeps to estimate distance. Results vary with surface and orientation; use background calibration for best accuracy.
• Doppler Velocity: Transmits a 20 kHz tone and measures frequency shift from moving objects to estimate velocity. Best for motion toward or away from the device.
• Metal Detector: Uses the magnetometer to detect ferromagnetic metals (iron, steel, etc.). Sensitivity varies by device; best for close-range detection.

These may have accuracy limitations or unexpected behavior. They are intended for experimentation and education.

To record sensor data:

• Open any sensor detail view
• Tap the Start button to begin collecting data
• Tap Record to start saving the session
• Tap Stop Rec when finished

Your recording will be saved automatically and available in the Recordings list.

To export recordings:

• Tap the clipboard icon in the top right corner
• Find your recording in the list
• Tap the share button
• Choose CSV (for spreadsheets) or JSON (for developers)
• Save to Files, email, AirDrop, or any other app

CSV (Comma-Separated Values):

• Best for spreadsheet apps (Excel, Google Sheets, Numbers)
• Easy to open and analyze with charts
• Format: timestamp,x,y,z,magnitude

JSON (JavaScript Object Notation):

• Best for developers and programming
• Includes metadata (session ID, sensor type, start/end times)
• Easily parsed by Python, JavaScript, Swift, etc.

No. Just Sensors is built with privacy as a core principle:

• All sensor data stays on your device
• No accounts or sign-ups required
• No analytics or tracking
• No ads or advertising SDKs
• No data sent to any servers

Read our full Privacy Policy for more details.

Absolutely not. Just Sensors has zero tracking:

• No user analytics or behavior tracking
• No crash reporting services that collect data
• No third-party SDKs that phone home
• No location tracking in the background
• No data shared with advertisers or data brokers

The app works entirely offline. Your sensor data never leaves your device unless you choose to export and share it.

Recordings are stored locally in the app's private storage on your device. They are:

• Only accessible by the Just Sensors app
• Included in iCloud backups (if enabled)
• Deleted when you uninstall the app

You can delete individual recordings anytime from the Recordings list.

Since Just Sensors stores all data locally on your device, you have complete control:

To delete individual recordings:

• Tap the clipboard icon to open Recordings
• Swipe left on a recording
• Tap Delete

To delete all app data:

• Uninstall the Just Sensors app from your device
• This removes all recordings and settings

Note: No data is stored on external servers, so there's nothing to delete remotely. Uninstalling the app completely removes all traces of your data.

No. Face Tracking and LiDAR data exist only in real-time while those features are active:

• When you leave the Face Tracking or LiDAR screen, all data is immediately discarded
• No facial geometry, images, or depth maps are ever saved
• If you record a session, only numerical values are saved (blend shape percentages for Face Tracking, distance values for LiDAR)
• No images, 3D models, or identifiable data is ever stored

See our Privacy Policy for complete details on how we handle TrueDepth and LiDAR data.

Sensor monitoring can use battery, especially GPS, camera, and AR features. To reduce battery usage:

• Return to the home screen when not actively viewing sensors
• Tap Stop on sensors you're not using
• Avoid leaving AR sensors (LiDAR, Face Tracking) running
• Close the app completely when done

If GPS isn't working:

• Ensure Location permission is set to "While Using" in Settings
• Make sure you're not in Airplane Mode
• Try going outdoors for better GPS signal
• Restart the app if location seems stuck

If the microphone isn't detecting sound:

• Check that Microphone permission is granted in Settings
• Make sure no other app is using the microphone
• Ensure your device isn't in Silent Mode (though this shouldn't affect input)
• Try restarting the app

If Face Tracking isn't working:

• Make sure you're using a device with TrueDepth camera (iPhone X or later with Face ID)
• Ensure adequate lighting — the TrueDepth camera works best in good light
• Hold your face 10-20 inches from the screen
• Make sure nothing is covering the TrueDepth camera (top notch area)
• Remove any screen protectors that might block the sensors
• Try restarting the app

If NFC scanning isn't working:

• Make sure you're using iPhone 7 or later
• Hold the top of your iPhone near the tag (that's where the NFC antenna is)
• Hold steady for 1-2 seconds
• Try removing your phone case — thick cases can interfere
• Make sure the tag is NDEF-formatted (most commercial NFC tags are)
• Ensure no metal is between the phone and the tag
• Some tags require very close proximity — try touching the tag

If the Bluetooth scanner shows no devices:

• Make sure Bluetooth permission is granted in Settings
• Check that Bluetooth is enabled on your device
• The scanner only detects Bluetooth Low Energy (BLE) devices — older Classic Bluetooth devices won't appear
• Make sure nearby devices are powered on and advertising
• Try moving closer to known BLE devices (AirPods, Apple Watch, fitness trackers)
• Pull down to refresh the scan