iLDM 150 - lz1asl/CaveSurvey GitHub Wiki

Device

Cheap device with 70m range and +/-65' clinometer. Precision of 1.5mm for the distance and 0.5' from the clinometer.

http://www.cem-instruments.in/product.php?pname=iLDM-150

Specifications

Usage

To use with CaveSurvey:

• Configure to work in meters and degrees, distance and inclination over Bluetooth.
• For distance select a cell and press the measurement button on the device twice.
• For inclination switch to the "inclination" mode and select the inclination cell. You should see the measurements updated in real time. Press a key to fix the current value.

iLDM Bluetooth Protocol

Note, only a subset of the protocol will be used for this project.

To establish connection:

• Discover the device
• Cancel the discovery
• Get BluetoothSocket as a client calling createInsecureRfcommSocketToServiceRecord to 00001101-0000-1000-8000-00805F9B34FB (see http://developer.android.com/reference/android/bluetooth/BluetoothDevice.html - createInsecureRfcommSocketToServiceRecord(UUID))

To send a message:

• Prepare command as a hexadecimal String and encode to byte array: "D5 F0 " + command + " 0D" (spaces were used for clarity), where command codes vary from "E0" to "EF"
• Write to the BluetoothSocket.getOutputStream()

To handle the response:

• Thread to retry reading in a byte buffer
• Messages are 25b long
• Starting "-43" bytes are removed
• Valid packet is extracted
• bytes:
  • byte 0:
  • byte 5: error code
  • byte 6: recording mode:
    • 1 from top of the device
    • 2 from bottom of the device
  • byte 7: measure unit, index for " ", "m", "in", "in+", "ft", "ft&in"
  • 4 measures, each encoded in 4 bytes: int measure = (0xFF000000 & buffer[(8 + j * 4)] << 24 | 0xFF0000 & buffer[(9 + j * 4)] << 16 | 0xFF00 & buffer[(10 + j * 4)] << 8 | 0xFF & buffer[(11 + j * 4)]); where:
    • missing values are encoded as large negative values, e.g. -26843545
    • 10.1' angle is represented as "101"
    • 2.43m distance is represented as "2430"
    • depending of the mode the places of the measures may vary
  • byte 25: should be 13 (data validation)

MeterMode Commands:

• 0 = Single
• 1 = Continuous
• 2 = Area
• 3 = Volume
• 4 = TwoTriangle
• 5 = ThreeTriangle1
• 6 = ThreeTriangle2
• 7 = DipDistance
• 8 = Addition
• 9 = subtraction
• 10 = Timing
• 11 = Stakeout
• 12 = AutoHorizontal
• 13 = AutoVertical
• 14 = AutoThreeTriangle1
• 15 = AutoThreeTriangle2