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Vectronix Terrapin-X laser rangefinder protocol
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@platypii
platypii committed Oct 26, 2024
1 parent 1d830c4 commit 8e99e47
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50 changes: 50 additions & 0 deletions app/src/main/java/com/platypii/baseline/lasers/rangefinder/Crc16.java
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package com.platypii.baseline.lasers.rangefinder;

class Crc16 {
/**
* Computes the CRC16 checksum for a given byte array.
*/
public static short crc16(byte[] byteArray) {
int crc = 65535;
for (byte b : byteArray) {
int index = (crc ^ (b & 0xff)) & 0xff;
crc = (crc >> 8) ^ CRC16_LOOKUP_TABLE[index];
}
return (short) crc;
}

private static final int[] CRC16_LOOKUP_TABLE = {
0, 4489, 8978, 12955, 17956, 22445, 25910, 29887,
35912, 40385, 44890, 48851, 51820, 56293, 59774, 63735,
4225, 264, 13203, 8730, 22181, 18220, 30135, 25662,
40137, 36160, 49115, 44626, 56045, 52068, 63999, 59510,
8450, 12427, 528, 5017, 26406, 30383, 17460, 21949,
44362, 48323, 36440, 40913, 60270, 64231, 51324, 55797,
12675, 8202, 4753, 792, 30631, 26158, 21685, 17724,
48587, 44098, 40665, 36688, 64495, 60006, 55549, 51572,
16900, 21389, 24854, 28831, 1056, 5545, 10034, 14011,
52812, 57285, 60766, 64727, 34920, 39393, 43898, 47859,
21125, 17164, 29079, 24606, 5281, 1320, 14259, 9786,
57037, 53060, 64991, 60502, 39145, 35168, 48123, 43634,
25350, 29327, 16404, 20893, 9506, 13483, 1584, 6073,
61262, 65223, 52316, 56789, 43370, 47331, 35448, 39921,
29575, 25102, 20629, 16668, 13731, 9258, 5809, 1848,
65487, 60998, 56541, 52564, 47595, 43106, 39673, 35696,
33800, 38273, 42778, 46739, 49708, 54181, 57662, 61623,
2112, 6601, 11090, 15067, 20068, 24557, 28022, 31999,
38025, 34048, 47003, 42514, 53933, 49956, 61887, 57398,
6337, 2376, 15315, 10842, 24293, 20332, 32247, 27774,
42250, 46211, 34328, 38801, 58158, 62119, 49212, 53685,
10562, 14539, 2640, 7129, 28518, 32495, 19572, 24061,
46475, 41986, 38553, 34576, 62383, 57894, 53437, 49460,
14787, 10314, 6865, 2904, 32743, 28270, 23797, 19836,
50700, 55173, 58654, 62615, 32808, 37281, 41786, 45747,
19012, 23501, 26966, 30943, 3168, 7657, 12146, 16123,
54925, 50948, 62879, 58390, 37033, 33056, 46011, 41522,
23237, 19276, 31191, 26718, 7393, 3432, 16371, 11898,
59150, 63111, 50204, 54677, 41258, 45219, 33336, 37809,
27462, 31439, 18516, 23005, 11618, 15595, 3696, 8185,
63375, 58886, 54429, 50452, 45483, 40994, 37561, 33584,
31687, 27214, 22741, 18780, 15843, 11370, 7921, 3960
};
}
1 change: 1 addition & 0 deletions app/src/main/java/com/platypii/baseline/lasers/rangefinder/RangefinderService.java
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Expand Up @@ -30,6 +30,7 @@ public class RangefinderService {
private final BleProtocol protocols[] = {
new ATNProtocol(),
new SigSauerProtocol(),
new TerrapinProtocol(),
new UineyeProtocol()
};

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235 changes: 235 additions & 0 deletions app/src/main/java/com/platypii/baseline/lasers/rangefinder/TerrapinProtocol.java
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package com.platypii.baseline.lasers.rangefinder;

import com.platypii.baseline.bluetooth.BleException;
import com.platypii.baseline.bluetooth.BleProtocol;
import com.platypii.baseline.lasers.LaserMeasurement;
import com.platypii.baseline.util.Exceptions;

import android.bluetooth.le.ScanRecord;
import android.os.ParcelUuid;
import android.util.Log;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import com.welie.blessed.BluetoothPeripheral;
import com.welie.blessed.WriteType;
import java.util.Arrays;
import java.util.List;
import java.util.UUID;
import org.greenrobot.eventbus.EventBus;

import static com.platypii.baseline.bluetooth.BluetoothUtil.byteArrayToHex;
import static com.platypii.baseline.bluetooth.BluetoothUtil.toManufacturerString;

/**
* This class contains ids, commands, and decoders for Vectronix Terrapin-X laser rangefinders.
*/
class TerrapinProtocol extends BleProtocol {
private static final String TAG = "TerrapinProtocol";

// Manufacturer ID
private static final int manufacturerId1 = 1164;
private static final byte[] manufacturerData1 = {1, -96, -1, -1, -1, -1, 0}; // 01-a0-ff-ff-ff-ff-00

// Terrapin service
private static final UUID terrapinService = UUID.fromString("81480000-b0b7-4074-8a24-ae554e5cdbc4");
// Terrapin characteristic: read, indicate
private static final UUID terrapinCharacteristic1 = UUID.fromString("81480100-b0b7-4074-8a24-ae554e5cdbc4");
// Terrapin characteristic: notify, write
private static final UUID terrapinCharacteristic2 = UUID.fromString("81480200-b0b7-4074-8a24-ae554e5cdbc4");

private static final String factoryModeSecretKey = "b6987833";

// Terrapin packet types
private static final short packetTypeCommand = 0x0000;
private static final short packetTypeData = 0x0300;
private static final short packetTypeAck = 0x0400;
private static final short packetTypeNack = 0x0500;

// Terrapin commands
private static final short commandNewMeasurementAvailable = 0x0010;
private static final short commandStartMeasurement = 0x0110;
private static final short commandGetLastRange = 0x0210;
private static final short commandGetLastInclination = 0x0310;
private static final short commandGetLastDirection = 0x0410;
private static final short commandGetLastTemperature = 0x0510;
private static final short commandGetLastPressure = 0x0610;
private static final short commandGetLastEHR = 0x0710;

// private static final short commandGetComVersion = 0x0100;
// private static final short commandGetSupportedCommandSet = 0x0200;
// private static final short commandGetSerialNumber = 0x0300;
// private static final short commandActivateFactoryMode = 0x0400;
// private static final short commandGetHardwareRevision = 0x0500;
// private static final short commandGetFirmwareVersion = 0x0600;
// private static final short commandGetBatteryLevel = 0x0700;
// private static final short commandGetDeviceName = 0x0800;
// private static final short commandSetDeviceName = 0x0900;
// private static final short commandGetDeviceId = 0x0a00;

@Override
public void onServicesDiscovered(@NonNull BluetoothPeripheral peripheral) {
try {
// Request rangefinder service
Log.i(TAG, "app -> rf: subscribe");
peripheral.setNotify(terrapinService, terrapinCharacteristic1, true);
} catch (Throwable e) {
Log.e(TAG, "rangefinder handshake exception", e);
}
}

@Override
public void processBytes(@NonNull BluetoothPeripheral peripheral, @NonNull byte[] value) {
Log.d(TAG, "rf -> app: process " + byteArrayToHex(value));
if (value[0] != 0x7e || value[value.length - 1] != 0x7e) {
Log.w(TAG, "rf -> app: invalid command " + byteArrayToHex(value));
return;
}

// Remove frame
byte[] frame = Arrays.copyOfRange(value, 1, value.length - 1);
// Unescape special characters 0x7e and 0x7d
frame = unescape(frame);

// Check checksum
final int checksum = frame[frame.length - 2] + (frame[frame.length - 1] << 8);
if (Crc16.crc16(frame) != checksum) {
Log.w(TAG, "rf -> app: invalid checksum " + byteArrayToHex(frame) + " " + Integer.toHexString(Crc16.crc16(frame)) + " != " + Integer.toHexString(checksum));
}

// Packet types
if (frame[0] + (frame[1] << 8) == packetTypeCommand) {
// Data length
int dataLength = frame[3] + (frame[2] << 8);
if (dataLength == 512) dataLength = 0;
// Command
final int command = frame[5] + (frame[4] << 8);
final byte[] data = Arrays.copyOfRange(frame, 6, frame.length - 2);
if (command == commandNewMeasurementAvailable) {
Log.i(TAG, "rf -> app: new measurement available " + byteArrayToHex(data));
getLastRange(peripheral);
} else {
Log.w(TAG, "rf -> app: command unknown 0x" + Integer.toHexString(command) + " " + dataLength + " " + byteArrayToHex(data));
}
} else if (frame[0] + (frame[1] << 8) == packetTypeData) {
Log.i(TAG, "rf -> app: data " + byteArrayToHex(frame));
} else if (frame[0] + (frame[1] << 8) == packetTypeAck) {
Log.i(TAG, "rf -> app: ack " + byteArrayToHex(frame));
} else if (frame[0] + (frame[1] << 8) == packetTypeNack) {
Log.i(TAG, "rf -> app: nack " + byteArrayToHex(frame));
} else {
Log.w(TAG, "rf -> app: unknown " + byteArrayToHex(frame));
}
}

private void processMeasurement(@NonNull byte[] value) {
Log.d(TAG, "rf -> app: measure " + byteArrayToHex(value));
// TODO
EventBus.getDefault().post(new LaserMeasurement(0, 0));
}
private void startMeasurement(@NonNull BluetoothPeripheral peripheral) {
Log.i(TAG, "app -> rf: start measurement");
sendCommand(peripheral, commandStartMeasurement, null);
}

private void getLastRange(@NonNull BluetoothPeripheral peripheral) {
Log.i(TAG, "app -> rf: get last range");
sendCommand(peripheral, commandGetLastRange, null);
}

private void sendCommand(@NonNull BluetoothPeripheral peripheral, short command, @Nullable byte[] data) {
final int dataLength = data == null ? 0 : data.length; // TODO: / 2 ?
byte[] frame = new byte[dataLength + 6];
// Packet type
frame[0] = (byte) (packetTypeCommand & 0xff);
frame[1] = (byte) ((packetTypeCommand >> 8) & 0xff);
// Data length
if (data != null) {
frame[2] = (byte) (dataLength & 0xff);
frame[3] = (byte) ((dataLength >> 8) & 0xff);
System.arraycopy(data, 0, frame, 6, data.length);
} else {
frame[2] = 2;
frame[3] = 0;
}
// Command
frame[4] = (byte) (command & 0xff);
frame[5] = (byte) ((command >> 8) & 0xff);
// Data
// Checksum
final int checksum = Crc16.crc16(Arrays.copyOfRange(frame, 1, 7));
frame[frame.length - 2] = (byte) (checksum & 0xff);
frame[frame.length - 1] = (byte) ((checksum >> 8) & 0xff);
// Escape special characters 0x7e and 0x7d
frame = escape(frame);
// Wrap frame
byte[] wrapped = new byte[frame.length + 2];
wrapped[0] = 0x7e;
System.arraycopy(frame, 0, wrapped, 1, frame.length);
wrapped[wrapped.length - 1] = 0x7e;
Log.d(TAG, "app -> rf: send command " + byteArrayToHex(wrapped));
peripheral.writeCharacteristic(terrapinService, terrapinCharacteristic2, wrapped, WriteType.WITH_RESPONSE);
}

/**
* Return true iff a bluetooth scan result looks like a rangefinder
*/
@Override
public boolean canParse(@NonNull BluetoothPeripheral peripheral, @Nullable ScanRecord record) {
final String deviceName = peripheral.getName();
if (record != null && Arrays.equals(record.getManufacturerSpecificData(manufacturerId1), manufacturerData1)) {
return true; // Manufacturer match (kenny's laser)
} else if (
(record != null && hasRangefinderService(record))
|| deviceName.startsWith("FastM")
|| deviceName.startsWith("Terrapin")) {
// Send manufacturer data to firebase
final String mfg = toManufacturerString(record);
Exceptions.report(new BleException("Terrapin laser unknown mfg data: " + deviceName + " " + mfg));
return true;
} else {
return false;
}
}

private boolean hasRangefinderService(@NonNull ScanRecord record) {
final List<ParcelUuid> uuids = record.getServiceUuids();
return uuids != null && uuids.contains(new ParcelUuid(terrapinService));
}

private byte[] escape(byte[] data) {
final byte[] escaped = new byte[data.length * 2];
int j = 0;
for (byte b : data) {
if (b == 0x7e) {
escaped[j++] = 0x7d;
escaped[j++] = 0x5e;
} else if (b == 0x7d) {
escaped[j++] = 0x7d;
escaped[j++] = 0x5d;
} else {
escaped[j++] = b;
}
}
return Arrays.copyOf(escaped, j);
}

private byte[] unescape(byte[] data) {
final byte[] unescaped = new byte[data.length];
int j = 0;
for (int i = 0; i < data.length; i++) {
if (data[i] == 0x7d) {
if (data[i + 1] == 0x5e) {
unescaped[j++] = 0x7e;
} else if (data[i + 1] == 0x5d) {
unescaped[j++] = 0x7d;
} else {
Log.w(TAG, "rf -> app: invalid escape sequence " + byteArrayToHex(data));
}
i++;
} else {
unescaped[j++] = data[i];
}
}
return Arrays.copyOf(unescaped, j);
}
}

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