Distance Meter

The Distance Meter is a tool that allows you to use the JedEye's sensors (Lidar and IMU) to measure distance, azimuth, and pitch in real-time without recording the data as a shot in a survey.

Access

Navigate to OPTIONS > TOOLS > DISTANCE METER in the main menu.

Interface

When active, the screen displays the real-time readings from the sensors:

• Distance: Distance to the target in the selected unit.
• Azimuth: Magnetic heading (compass bearing).
• Pitch: Vertical angle (inclination).

In the menu you can choose:

• MEASURE: Capture the current readings and broadcasts it on Bluetooth
• EXIT: Return to the Tools menu.

Usage

taking a Measurement

1. Aim the device at the target.
2. Ensure the MEASURE option is selected (use the Next button to toggle if needed).
3. Press the Select button.
   • The screen will flash white briefly to confirm the action.
   • The "Saved" values on the screen will update to the captured readings.
   • The captured values (Distance, Azimuth, Pitch) are broadcasted via Bluetooth Low Energy (BLE) to any connected device.

Exiting

1. Press the Next button to select EXIT.
2. Press the Select button to leave the Distance Meter mode.

Bluetooth Broadcasting

While in Distance Meter mode, the JedEye advertises a Bluetooth Low Energy service so survey apps can collect each captured shot in real time. WiFi is turned off automatically when you enter this mode (the radio module does either WiFi or BLE, never both).

The device advertises itself as JedEye_<serial>, where <serial> is the 16-hex-digit unique ID of the underlying processor (e.g. JedEye_009315501C7B8A58).

A small Bluetooth icon appears in the bottom-right corner of the screen when BLE advertising is active.

TopoDroid integration

JedEye is supported as a first-class device in TopoDroid (cave surveying app for Android).

1. On the JedEye, enter the Distance Meter screen so it begins advertising.
2. In TopoDroid, open the Device screen and run BT Scan from the menu. The JedEye appears in the list with model "JedEye".
3. Tap the entry to register it. The pairing only needs to be done once; subsequent connections happen automatically whenever the JedEye is in Distance Meter mode.

Once paired:

• Each measurement you capture on the JedEye (by selecting MEASURE) is streamed to TopoDroid as a single shot — distance, azimuth, clino, and roll — and lands directly in the survey's shot list with auto-assigned station names.
• TopoDroid can also send a remote MEASURE command from the app side, which triggers a capture on the JedEye without touching the device. Useful when the JedEye is mounted on a tripod.
• The JedEye uses continuous streaming only: shots taken while not connected are not buffered and re-transmitted later. Connect TopoDroid before capturing if you want the shots to land in the survey.

Protocol details

For app authors who want to consume the shot stream directly without going through TopoDroid:

Item	UUID	Properties	Format
Service	4A454445-5945-0001-8000-00805F9B34FB	—	—
Shot notification	4A454445-5945-0002-8000-00805F9B34FB	Read + Notify	17 bytes
Command write	4A454445-5945-0003-8000-00805F9B34FB	Write / WriteWithoutResponse	1 byte

Each shot notification is 17 bytes: a 1-byte sequence number followed by four little-endian IEEE-754 float32 values — bearing in degrees, clino in degrees, roll in degrees, distance in metres (in that order). This is the same shot-frame layout as the SAP6 instrument; only the GATT service UUIDs differ.

Single-byte commands accepted on the command characteristic:

Code	Meaning
0x36	Laser on (start the lidar)
0x37	Laser off (stop the lidar)
0x38	Trigger a measurement and emit a shot notification
0x30 / 0x31	Calibration off / on — reserved, currently no-op
0x34	Device off — reserved, currently no-op

NINA firmware requirement. The TopoDroid-compatible BLE protocol requires NINA radio firmware 3.0.1 or newer. Devices shipped with firmware older than v2.3 carry NINA firmware 1.5.0 and need a one-time radio firmware update — see Updating the NINA firmware for the walk-through.