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Vectronix Terrapin-X laser rangefinder protocol
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‎app/src/main/java/com/platypii/baseline/lasers/rangefinder/Crc16.java

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package com.platypii.baseline.lasers.rangefinder;
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class Crc16 {
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/**
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* Computes the CRC16 checksum for a given byte array.
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*/
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public static short crc16(byte[] byteArray) {
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int crc = 0xffff;
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// Process bytes in pairs (LSB first)
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for (int i = 0; i < byteArray.length; i++) {
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int b = byteArray[i] & 0xFF;
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crc ^= b;
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// Process each bit
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for (int j = 0; j < 8; j++) {
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if ((crc & 0x0001) != 0) {
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crc = (crc >> 1) ^ 0x8408; // 0x8408 is reversed polynomial
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} else {
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crc = crc >> 1;
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}
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}
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}
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// XOR with 0xfff
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crc ^= 0xffff;
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// Swap the bytes of the result
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crc = ((crc & 0xFF) << 8) | ((crc >> 8) & 0xFF);
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return (short) crc;
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}
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private static final int[] CRC16_LOOKUP_TABLE = {
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0, 4489, 8978, 12955, 17956, 22445, 25910, 29887,
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35912, 40385, 44890, 48851, 51820, 56293, 59774, 63735,
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4225, 264, 13203, 8730, 22181, 18220, 30135, 25662,
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40137, 36160, 49115, 44626, 56045, 52068, 63999, 59510,
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8450, 12427, 528, 5017, 26406, 30383, 17460, 21949,
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44362, 48323, 36440, 40913, 60270, 64231, 51324, 55797,
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12675, 8202, 4753, 792, 30631, 26158, 21685, 17724,
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48587, 44098, 40665, 36688, 64495, 60006, 55549, 51572,
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16900, 21389, 24854, 28831, 1056, 5545, 10034, 14011,
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52812, 57285, 60766, 64727, 34920, 39393, 43898, 47859,
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21125, 17164, 29079, 24606, 5281, 1320, 14259, 9786,
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57037, 53060, 64991, 60502, 39145, 35168, 48123, 43634,
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25350, 29327, 16404, 20893, 9506, 13483, 1584, 6073,
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61262, 65223, 52316, 56789, 43370, 47331, 35448, 39921,
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29575, 25102, 20629, 16668, 13731, 9258, 5809, 1848,
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65487, 60998, 56541, 52564, 47595, 43106, 39673, 35696,
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33800, 38273, 42778, 46739, 49708, 54181, 57662, 61623,
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2112, 6601, 11090, 15067, 20068, 24557, 28022, 31999,
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38025, 34048, 47003, 42514, 53933, 49956, 61887, 57398,
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6337, 2376, 15315, 10842, 24293, 20332, 32247, 27774,
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42250, 46211, 34328, 38801, 58158, 62119, 49212, 53685,
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10562, 14539, 2640, 7129, 28518, 32495, 19572, 24061,
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46475, 41986, 38553, 34576, 62383, 57894, 53437, 49460,
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14787, 10314, 6865, 2904, 32743, 28270, 23797, 19836,
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50700, 55173, 58654, 62615, 32808, 37281, 41786, 45747,
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19012, 23501, 26966, 30943, 3168, 7657, 12146, 16123,
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54925, 50948, 62879, 58390, 37033, 33056, 46011, 41522,
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23237, 19276, 31191, 26718, 7393, 3432, 16371, 11898,
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59150, 63111, 50204, 54677, 41258, 45219, 33336, 37809,
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27462, 31439, 18516, 23005, 11618, 15595, 3696, 8185,
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63375, 58886, 54429, 50452, 45483, 40994, 37561, 33584,
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31687, 27214, 22741, 18780, 15843, 11370, 7921, 3960
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};
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}

‎app/src/main/java/com/platypii/baseline/lasers/rangefinder/RangefinderService.java

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@@ -30,6 +30,7 @@ public class RangefinderService {
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private final BleProtocol protocols[] = {
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new ATNProtocol(),
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new SigSauerProtocol(),
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new TerrapinProtocol(),
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new UineyeProtocol()
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};
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‎app/src/main/java/com/platypii/baseline/lasers/rangefinder/TerrapinProtocol.java

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package com.platypii.baseline.lasers.rangefinder;
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import com.platypii.baseline.bluetooth.BleException;
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import com.platypii.baseline.bluetooth.BleProtocol;
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import com.platypii.baseline.lasers.LaserMeasurement;
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import com.platypii.baseline.util.Exceptions;
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import android.bluetooth.le.ScanRecord;
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import android.os.ParcelUuid;
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import android.util.Log;
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import androidx.annotation.NonNull;
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import androidx.annotation.Nullable;
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import com.welie.blessed.BluetoothPeripheral;
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import com.welie.blessed.WriteType;
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import java.util.Arrays;
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import java.util.List;
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import java.util.UUID;
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import org.greenrobot.eventbus.EventBus;
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import static com.platypii.baseline.bluetooth.BluetoothUtil.byteArrayToHex;
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import static com.platypii.baseline.bluetooth.BluetoothUtil.toManufacturerString;
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/**
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* This class contains ids, commands, and decoders for Vectronix Terrapin-X laser rangefinders.
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*/
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class TerrapinProtocol extends BleProtocol {
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private static final String TAG = "TerrapinProtocol";
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// Manufacturer ID
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private static final int manufacturerId1 = 1164;
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private static final byte[] manufacturerData1 = {1, -96, -1, -1, -1, -1, 0}; // 01-a0-ff-ff-ff-ff-00
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// Terrapin service
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private static final UUID terrapinService = UUID.fromString("81480000-b0b7-4074-8a24-ae554e5cdbc4");
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// Terrapin characteristic: read, indicate
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private static final UUID terrapinCharacteristic1 = UUID.fromString("81480100-b0b7-4074-8a24-ae554e5cdbc4");
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// Terrapin characteristic: notify, write
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private static final UUID terrapinCharacteristic2 = UUID.fromString("81480200-b0b7-4074-8a24-ae554e5cdbc4");
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private static final String factoryModeSecretKey = "b6987833";
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// Terrapin packet types
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private static final short packetTypeCommand = 0x0000;
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private static final short packetTypeData = 0x0300;
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private static final short packetTypeAck = 0x0400;
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private static final short packetTypeNack = 0x0500;
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// Terrapin commands
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private static final short commandNewMeasurementAvailable = 0x0010;
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private static final short commandStartMeasurement = 0x0110;
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private static final short commandGetLastRange = 0x0210;
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private static final short commandGetLastInclination = 0x0310;
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private static final short commandGetLastDirection = 0x0410;
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private static final short commandGetLastTemperature = 0x0510;
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private static final short commandGetLastPressure = 0x0610;
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private static final short commandGetLastEHR = 0x0710;
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private static final short commandGetLaserMode = 0x2210;
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private static final short commandGetDeclination = 0x2710;
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private static final short commandGetRangeGate = 0x2810;
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private static final short commandGetLastSNR = 0x06f0;
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// private static final short commandGetComVersion = 0x0100;
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// private static final short commandGetSupportedCommandSet = 0x0200;
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// private static final short commandGetSerialNumber = 0x0300;
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// private static final short commandActivateFactoryMode = 0x0400;
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// private static final short commandGetHardwareRevision = 0x0500;
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// private static final short commandGetFirmwareVersion = 0x0600;
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// private static final short commandGetBatteryLevel = 0x0700;
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// private static final short commandGetDeviceName = 0x0800;
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// private static final short commandSetDeviceName = 0x0900;
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// private static final short commandGetDeviceId = 0x0a00;
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@Override
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public void onServicesDiscovered(@NonNull BluetoothPeripheral peripheral) {
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try {
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// Request rangefinder service
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Log.i(TAG, "app -> rf: subscribe");
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peripheral.setNotify(terrapinService, terrapinCharacteristic1, true);
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} catch (Throwable e) {
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Log.e(TAG, "rangefinder handshake exception", e);
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}
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}
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@Override
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public void processBytes(@NonNull BluetoothPeripheral peripheral, @NonNull byte[] value) {
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Log.d(TAG, "rf -> app: processBytes " + byteArrayToHex(value));
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if (value[0] != 0x7e || value[value.length - 1] != 0x7e) {
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Log.w(TAG, "rf -> app: invalid command " + byteArrayToHex(value));
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return;
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}
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// Remove frame
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byte[] frame = Arrays.copyOfRange(value, 1, value.length - 1);
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// Unescape special characters 0x7e and 0x7d
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frame = unescape(frame);
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// Check checksum
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final int checksumValue = getShort(frame, frame.length - 2);
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byte[] checksumContent = Arrays.copyOfRange(frame, 0, frame.length - 2);
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final short checksumComputed = Crc16.crc16(checksumContent);
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if (checksumValue != checksumComputed) {
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Log.w(TAG, "rf -> app: invalid checksum " + byteArrayToHex(checksumContent) + " " + shortToHex(checksumValue) + " != " + shortToHex(checksumComputed));
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}
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// Packet types
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final short packetType = getShort(frame, 0);
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if (packetType == packetTypeCommand) {
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// Data length
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int dataLength = getShort(frame, 2);
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if (dataLength == 512) dataLength = 0;
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// Command
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final int command = getShort(frame, 4);
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final byte[] data = Arrays.copyOfRange(frame, 6, frame.length - 2);
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if (command == commandNewMeasurementAvailable) {
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Log.i(TAG, "rf -> app: new measurement available");
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getLastRange(peripheral);
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} else {
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Log.w(TAG, "rf -> app: command unknown 0x" + shortToHex(command) + " " + dataLength + " " + byteArrayToHex(data));
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}
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} else if (packetType == packetTypeData) {
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Log.i(TAG, "rf -> app: data " + byteArrayToHex(frame));
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} else if (packetType == packetTypeAck) {
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Log.i(TAG, "rf -> app: ack " + byteArrayToHex(frame));
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} else if (packetType == packetTypeNack) {
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Log.i(TAG, "rf -> app: nack " + byteArrayToHex(frame));
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} else {
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Log.w(TAG, "rf -> app: unknown packet type " + shortToHex(packetType) + " " + byteArrayToHex(frame));
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}
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}
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private String shortToHex(int value) {
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return Integer.toHexString(value & 0xffff);
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}
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private void processMeasurement(@NonNull byte[] value) {
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Log.d(TAG, "rf -> app: measure " + byteArrayToHex(value));
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// TODO
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EventBus.getDefault().post(new LaserMeasurement(0, 0));
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}
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private void startMeasurement(@NonNull BluetoothPeripheral peripheral) {
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Log.i(TAG, "app -> rf: start measurement");
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sendCommand(peripheral, commandStartMeasurement, null);
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}
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private void getLastRange(@NonNull BluetoothPeripheral peripheral) {
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Log.i(TAG, "app -> rf: get last range");
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sendCommand(peripheral, commandGetLastRange, null);
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}
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private void sendCommand(@NonNull BluetoothPeripheral peripheral, short command, @Nullable byte[] data) {
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final int dataLength = data == null ? 0 : data.length; // TODO: / 2 ?
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byte[] frame = new byte[8 + dataLength];
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// Packet type
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frame[0] = (byte) (packetTypeCommand & 0xff);
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frame[1] = (byte) ((packetTypeCommand >> 8) & 0xff);
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// Data length
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if (data != null) {
158+
frame[2] = (byte) (dataLength & 0xff);
159+
frame[3] = (byte) ((dataLength >> 8) & 0xff);
160+
System.arraycopy(data, 0, frame, 6, data.length);
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} else {
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frame[2] = 2;
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frame[3] = 0;
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}
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// Command
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frame[4] = (byte) (command & 0xff);
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frame[5] = (byte) ((command >> 8) & 0xff);
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// Checksum
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final int checksum = Crc16.crc16(Arrays.copyOfRange(frame, 0, frame.length - 2));
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frame[frame.length - 2] = (byte) (checksum & 0xff);
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frame[frame.length - 1] = (byte) ((checksum >> 8) & 0xff);
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// Escape special characters 0x7e and 0x7d
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frame = escape(frame);
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// Wrap frame
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byte[] wrapped = new byte[frame.length + 2];
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wrapped[0] = 0x7e;
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System.arraycopy(frame, 0, wrapped, 1, frame.length);
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wrapped[wrapped.length - 1] = 0x7e;
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Log.d(TAG, "app -> rf: send command " + byteArrayToHex(wrapped));
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peripheral.writeCharacteristic(terrapinService, terrapinCharacteristic2, wrapped, WriteType.WITH_RESPONSE);
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}
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/**
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* Return true iff a bluetooth scan result looks like a rangefinder
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*/
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@Override
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public boolean canParse(@NonNull BluetoothPeripheral peripheral, @Nullable ScanRecord record) {
188+
final String deviceName = peripheral.getName();
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if (record != null && Arrays.equals(record.getManufacturerSpecificData(manufacturerId1), manufacturerData1)) {
190+
return true; // Manufacturer match (kenny's laser)
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} else if (
192+
(record != null && hasRangefinderService(record))
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|| deviceName.startsWith("FastM")
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|| deviceName.startsWith("Terrapin")) {
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// Send manufacturer data to firebase
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final String mfg = toManufacturerString(record);
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Exceptions.report(new BleException("Terrapin laser unknown mfg data: " + deviceName + " " + mfg));
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return true;
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} else {
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return false;
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}
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}
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private boolean hasRangefinderService(@NonNull ScanRecord record) {
205+
final List<ParcelUuid> uuids = record.getServiceUuids();
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return uuids != null && uuids.contains(new ParcelUuid(terrapinService));
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}
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private byte[] escape(byte[] data) {
210+
final byte[] escaped = new byte[data.length * 2];
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int j = 0;
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for (byte b : data) {
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if (b == 0x7e) {
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escaped[j++] = 0x7d;
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escaped[j++] = 0x5e;
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} else if (b == 0x7d) {
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escaped[j++] = 0x7d;
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escaped[j++] = 0x5d;
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} else {
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escaped[j++] = b;
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}
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}
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return Arrays.copyOf(escaped, j);
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}
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private byte[] unescape(byte[] data) {
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final byte[] unescaped = new byte[data.length];
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int j = 0;
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for (int i = 0; i < data.length; i++) {
230+
if (data[i] == 0x7d) {
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if (data[i + 1] == 0x5e) {
232+
unescaped[j++] = 0x7e;
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} else if (data[i + 1] == 0x5d) {
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unescaped[j++] = 0x7d;
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} else {
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Log.w(TAG, "rf -> app: invalid escape sequence " + byteArrayToHex(data));
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}
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i++;
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} else {
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unescaped[j++] = data[i];
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}
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}
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return Arrays.copyOf(unescaped, j);
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}
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@NonNull
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private byte[] swapEndianness(@NonNull byte[] data) {
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if (data.length % 2 != 0) {
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Log.w(TAG, "rf -> app: data length must be even " + byteArrayToHex(data));
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}
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final byte[] swapped = new byte[data.length];
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for (int i = 0; i < data.length; i += 2) {
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swapped[i] = data[i + 1];
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swapped[i + 1] = data[i];
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}
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return swapped;
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}
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/**
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* Endian-swapped short from byte array
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*/
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private short getShort(@NonNull byte[] data, int offset) {
263+
return (short) ((data[offset + 1] & 0xff) | (data[offset] << 8));
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}
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}

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