initial support for Bosch ebike BLE power sensor

README_TESTED_SENSORS.md

@@ -112,3 +112,15 @@ Here is a list of the smartphones tested:
 | Google  | Nexus 4            | LineageOS 18.1  | Ok                                                                             |
 | Samsung | S4                 | Android 11      | Ok                                                                             |
 | Sony    | Xperia XZ1 Compact | LineageOS 16.1  | Failure                                                                        |
+
+## Bosch Smart System eBike
+
+OpenTracks also supports Bosch Smart System eBikes via Bosch's custom BLE service `00000010-eaa2-11e9-81b4-2a2ae2dbcce4`.
+
+Tested with:
+
+* Bosch Perfomance Line CX (SW-Version 16.9.0) / Kiox 300 (SW-Version 16.4.0)
+
+Currently supported measurements:
+
+* Human power

src/androidTest/java/de/dennisguse/opentracks/sensors/driver/BoschEbikeParserTest.java

@@ -0,0 +1,137 @@
+package de.dennisguse.opentracks.sensors.driver;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import org.junit.Test;
+
+public class BoschEbikeParserTest {
+
+    @Test
+    public void parse_multipleFrames_returnsCombinedMeasurements() {
+        byte[] raw = new byte[] {
+                // Bosch cadence frame
+                0x30, 0x04, (byte) 0x98, 0x5A, 0x08, 0x76,
+                // Bosch human power frame
+                0x30, 0x05, (byte) 0x98, 0x5B, 0x08, (byte) 0x83, 0x01,
+                // Bosch speed frame
+                0x30, 0x07, (byte) 0x98, 0x2D, 0x08, (byte) 0x94, 0x0B, 0x10, 0x01
+        };
+
+        BoschEbikeParser.Data data = BoschEbikeParser.parse(raw);
+
+        assertNotNull(data);
+        assertEquals(59.0f, data.cadence().getRPM(), 0.01f);
+        assertEquals(131.0f, data.humanPower().getW(), 0.01f);
+        assertEquals(14.28 / 3.6, data.speed().toMPS(), 0.0001);
+    }
+
+    @Test
+    public void parse_multiByteVarint_returnsScaledSpeed() {
+        // Bosch speed frame using a multi-byte varint
+        BoschEbikeParser.Data data = BoschEbikeParser.parse(new byte[] {
+                0x30, 0x07, (byte) 0x98, 0x2D, 0x08, (byte) 0xE1, 0x0E, 0x10, 0x01
+        });
+
+        assertNotNull(data);
+        assertEquals(18.89 / 3.6, data.speed().toMPS(), 0.0001);
+    }
+
+    @Test
+    public void parse_zeroValueFrame_returnsZeroCadence() {
+        // Bosch zero-value cadence frame
+        BoschEbikeParser.Data data = BoschEbikeParser.parse(new byte[] {
+                0x30, 0x02, (byte) 0x98, 0x5A
+        });
+
+        assertNotNull(data);
+        assertEquals(0.0f, data.cadence().getRPM(), 0.01f);
+        assertNull(data.speed());
+        assertNull(data.humanPower());
+    }
+
+    @Test
+    public void parse_unsupportedMeasurementsOnly_returnsNull() {
+        // Bosch frame for message 0x9865, which the parser does not map to a measurement.
+        BoschEbikeParser.Data data = BoschEbikeParser.parse(new byte[] {
+                0x30, 0x02, (byte) 0x98, 0x65
+        });
+
+        assertNull(data);
+    }
+
+    @Test
+    public void parse_unimplementedMeasurementsOnly_returnsNull() {
+        // Bosch motor power frame: message 0x985D with value 0x42, currently ignored.
+        BoschEbikeParser.Data data = BoschEbikeParser.parse(new byte[] {
+                0x30, 0x04, (byte) 0x98, 0x5D, 0x08, 0x42
+        });
+
+        assertNull(data);
+    }
+
+    @Test
+    public void parse_malformedVarint_returnsNull() {
+        // Truncated Bosch speed frame: starts like a real 0x982D frame but the varint is incomplete.
+        BoschEbikeParser.Data data = BoschEbikeParser.parse(new byte[] {
+                0x30, 0x04, (byte) 0x98, 0x2D, 0x08, (byte) 0x94
+        });
+
+        assertNull(data);
+    }
+
+    @Test
+    public void parse_varintLargerThan32Bit_returnsNull() {
+        BoschEbikeParser.Data data = BoschEbikeParser.parse(new byte[] {
+                0x30, 0x08, (byte) 0x98, 0x2D, 0x08,
+                (byte) 0x80, (byte) 0x80, (byte) 0x80, (byte) 0x80, (byte) 0x80, 0x01
+        });
+
+        assertNull(data);
+    }
+
+    @Test
+    public void parse_validMeasurementBeforeMalformedFrame_returnsValidMeasurement() {
+        BoschEbikeParser.Data data = BoschEbikeParser.parse(new byte[] {
+                // Bosch cadence frame: message 0x985A with value 0x76
+                0x30, 0x04, (byte) 0x98, 0x5A, 0x08, 0x76,
+                // Truncated Bosch speed frame: malformed trailing frame should not discard the valid cadence above.
+                0x30, 0x04, (byte) 0x98, 0x2D, 0x08, (byte) 0x94
+        });
+
+        assertNotNull(data);
+        assertEquals(59.0f, data.cadence().getRPM(), 0.01f);
+        assertNull(data.speed());
+    }
+
+    @Test
+    public void parse_malformedVarintDoesNotConsumeNextFrameStartByte() {
+        BoschEbikeParser.Data data = BoschEbikeParser.parse(new byte[] {
+                // Truncated Bosch speed frame: the varint continuation bit is set, but the frame ends
+                // before the next varint byte. The following frame start byte must not be consumed.
+                0x30, 0x04, (byte) 0x98, 0x2D, 0x08, (byte) 0x94,
+                // Bosch cadence frame: message 0x985A with value 0x76
+                0x30, 0x04, (byte) 0x98, 0x5A, 0x08, 0x76
+        });
+
+        assertNotNull(data);
+        assertNull(data.speed());
+        assertEquals(59.0f, data.cadence().getRPM(), 0.01f);
+    }
+
+    @Test
+    public void parse_leadingNoise_ignored() {
+        byte[] raw = new byte[] {
+                // Noise bytes to verify the parser resynchronizes on the Bosch frame start byte 0x30.
+                0x01, 0x02, 0x03,
+                // Bosch cadence frame: message 0x985A with value 0x76
+                0x30, 0x04, (byte) 0x98, 0x5A, 0x08, 0x76
+        };
+
+        BoschEbikeParser.Data data = BoschEbikeParser.parse(raw);
+
+        assertNotNull(data);
+        assertEquals(59.0f, data.cadence().getRPM(), 0.01f);
+    }
+}

src/androidTest/java/de/dennisguse/opentracks/sensors/driver/CyclingPowerBluetoothTest.java

@@ -1,6 +1,7 @@
 package de.dennisguse.opentracks.sensors.driver;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
 
 import android.bluetooth.BluetoothGattCharacteristic;
 
@@ -35,4 +36,27 @@ public class CyclingPowerBluetoothTest {
         assertEquals(17125, powerCadence.crank().crankRevolutionsTime());
     }
 
-}
+    @Test
+    public void parsePayload_boschPower() {
+        BluetoothGattCharacteristic characteristic = new BluetoothGattCharacteristic(BoschEbikeParser.BOSCH_EBIKE.measurementUUID(), 0, 0);
+        // Bosch human power frame: message 0x985B with value 0x7B => 123 W.
+        characteristic.setValue(new byte[] { 0x30, 0x04, (byte) 0x98, 0x5B, 0x08, 0x7B });
+
+        CyclingPowerBluetooth.Data power = new CyclingPowerBluetooth().parsePayload(BoschEbikeParser.BOSCH_EBIKE, null, characteristic);
+
+        assertEquals(123, power.power().getW(), 0.01);
+        assertNull(power.crank());
+    }
+
+    @Test
+    public void parsePayload_boschCadenceOnly_returnsNull() {
+        BluetoothGattCharacteristic characteristic = new BluetoothGattCharacteristic(BoschEbikeParser.BOSCH_EBIKE.measurementUUID(), 0, 0);
+        // Bosch cadence-only frame: message 0x985A with value 0x01B8 => 220 / 2 = 110 rpm, so power parsing should ignore it.
+        characteristic.setValue(new byte[] { 0x30, 0x05, (byte) 0x98, 0x5A, 0x08, (byte) 0xB8, 0x01 });
+
+        CyclingPowerBluetooth.Data power = new CyclingPowerBluetooth().parsePayload(BoschEbikeParser.BOSCH_EBIKE, null, characteristic);
+
+        assertNull(power);
+    }
+
+}

src/main/java/de/dennisguse/opentracks/sensors/driver/BoschEbikeParser.java

@@ -0,0 +1,217 @@
+package de.dennisguse.opentracks.sensors.driver;
+
+import android.util.Log;
+
+import androidx.annotation.Nullable;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.UUID;
+
+import de.dennisguse.opentracks.data.models.Cadence;
+import de.dennisguse.opentracks.data.models.Power;
+import de.dennisguse.opentracks.data.models.Speed;
+import de.dennisguse.opentracks.sensors.ServiceMeasurementUUID;
+
+// Implementation of metrics from a Bosch Smart System eBike via BLE.
+// as described and implemented here: https://github.com/RobbyPee/Bosch-Smart-System-Ebike-Garmin-Android
+//
+// The bike exposes a single custom BLE service with one notification characteristic onto
+// which all measurements are multiplexed as concatenated frames.
+//
+// ```
+// 30  <length>  <id-hi>  <id-lo>  [08  <varint...>]
+// ```
+//
+// Frame format
+//
+// - `30` : start byte
+// - `<length>` - number of payload bytes following (min 2, which means value = 0)
+// - two-byte big-endian message ID
+// - `08` : varint type tag (absent when value is 0)
+// - varint : strip MSB from each byte, 7-bit groups, little-endian concatenation
+//
+// Multiple frames may be packed into a single characteristic notification.
+//
+
+public final class BoschEbikeParser {
+
+    private static final String TAG = BoschEbikeParser.class.getSimpleName();
+
+    private static final int MESSAGE_ID_CADENCE = 0x985A;
+    private static final int MESSAGE_ID_HUMAN_POWER = 0x985B;
+    private static final int MESSAGE_ID_SPEED = 0x982D;
+    private static final int MESSAGE_ID_MOTOR_POWER = 0x985D;
+    private static final int MESSAGE_ID_BATTERY = 0x8088;
+    private static final int MESSAGE_ID_ASSIST_MODE = 0x9809;
+
+    private static final int START_BYTE = 0x30;
+    private static final int VARINT_TAG = 0x08;
+    private static final int MAX_VARINT_32_BIT_BYTES = 5;
+
+    public static final ServiceMeasurementUUID BOSCH_EBIKE = new ServiceMeasurementUUID(
+            UUID.fromString("00000010-eaa2-11e9-81b4-2a2ae2dbcce4"),
+            UUID.fromString("00000011-eaa2-11e9-81b4-2a2ae2dbcce4"));
+
+    private BoschEbikeParser() {
+    }
+
+    /**
+     * Decodes a single varint from {@code data}. Uses little-endian 7-bit groups; MSB=1 means another byte follows.
+     */
+    private static Integer decodeVarint(byte[] data) {
+        if (data == null || data.length == 0) {
+            Log.d(TAG, "Malformed varint: empty payload");
+            return null;
+        }
+
+        int result = 0;
+
+        for (int i = 0; i < data.length; i++) {
+            if (i >= MAX_VARINT_32_BIT_BYTES) {
+                Log.d(TAG, "Malformed varint: exceeds 32-bit limit after " + i + " bytes");
+                return null;
+            }
+
+            int byteValue = data[i] & 0x7F;
+            result |= byteValue << (7 * i);
+
+            if ((data[i] & 0x80) == 0) {
+                return result;
+            }
+        }
+
+        Log.d(TAG, "Malformed varint: truncated after " + data.length + " bytes");
+        return null;
+    }
+
+    /**
+     * Parses one Bosch notification payload, which may contain multiple concatenated frames, and returns the measurements recognized in that payload.
+     */
+    static Data parse(byte[] raw) {
+        if (raw == null || raw.length == 0) {
+            return null;
+        }
+
+        Data data = splitFrames(raw).stream()
+                .filter(BoschEbikeParser::isValidFrame)
+                .filter(BoschEbikeParser::isSupportedFrame)
+                .map(BoschEbikeParser::decodeFrame)
+                .filter(decodedFrame -> decodedFrame != null)
+                .reduce(null,
+                        BoschEbikeParser::processMessage,
+                        (left, right) -> right);
+        Log.d(TAG, "Parsed Bosch data: " + data);
+        return data;
+    }
+
+    private static List<byte[]> splitFrames(byte[] raw) {
+        List<byte[]> frames = new ArrayList<>();
+
+        int i = 0;
+        while (i < raw.length) {
+            if (raw[i] != START_BYTE) {
+                i++;
+                continue;
+            }
+
+            if (i + 1 >= raw.length) {
+                Log.d(TAG, "Malformed frame at offset " + i + ": missing length byte (raw length=" + raw.length + ")");
+                i++;
+                continue;
+            }
+
+            int length = raw[i + 1] & 0xFF;
+            int frameEnd = i + length + 2;
+            frames.add(Arrays.copyOfRange(raw, i, Math.min(frameEnd, raw.length)));
+            i = frameEnd;
+        }
+
+        return frames;
+    }
+
+    private static boolean isValidFrame(byte[] frame) {
+        int length = getFrameLength(frame);
+        if (length < 2) {
+            Log.d(TAG, "Malformed frame: payload length " + length + " is shorter than minimum 2 bytes");
+            return false;
+        }
+
+        if (frame.length != length + 2) {
+            Log.d(TAG, "Malformed frame: expected " + (length + 2) + " bytes, got " + frame.length);
+            return false;
+        }
+
+        return true;
+    }
+
+    private static boolean isSupportedFrame(byte[] frame) {
+        boolean supported = getFrameLength(frame) == 2 || (frame[4] & 0xFF) == VARINT_TAG;
+        if (!supported) {
+            Log.d(TAG, "Unsupported frame: tag 0x" + String.format("%02X", frame[4] & 0xFF));
+        }
+        return supported;
+    }
+
+    @Nullable
+    private static DecodedFrame decodeFrame(byte[] frame) {
+        if (getFrameLength(frame) == 2) {
+            return new DecodedFrame(getMessageId(frame), 0);
+        }
+
+        Integer varintResult = decodeVarint(Arrays.copyOfRange(frame, 5, frame.length));
+        if (varintResult == null) {
+            return null;
+        }
+
+        return new DecodedFrame(getMessageId(frame), varintResult);
+    }
+
+    private static int getFrameLength(byte[] frame) {
+        return frame[1] & 0xFF;
+    }
+
+    private static int getMessageId(byte[] frame) {
+        return (frame[2] & 0xFF) << 8 | (frame[3] & 0xFF);
+    }
+
+    /**
+     * Processes a message ID and value, updating the data with any measurements.
+     */
+    @Nullable
+    private static Data processMessage(@Nullable Data data, DecodedFrame decodedFrame) {
+        switch (decodedFrame.messageId()) {
+            case MESSAGE_ID_CADENCE:
+                return new Data(null, Cadence.of(decodedFrame.value() / 2.0f), null, data);
+            case MESSAGE_ID_HUMAN_POWER:
+                return new Data(null, null, Power.of((float) decodedFrame.value()), data);
+            case MESSAGE_ID_SPEED:
+                double speed_kmh = decodedFrame.value() / 100.0;
+                return new Data(Speed.ofKMH(speed_kmh), null, null, data);
+            case MESSAGE_ID_MOTOR_POWER:
+            case MESSAGE_ID_BATTERY:
+            case MESSAGE_ID_ASSIST_MODE:
+                Log.d(TAG, "Ignoring unimplemented message: raw=" + decodedFrame.value());
+                return data;
+        }
+        Log.d(TAG, "Ignoring unknown message: raw=" + decodedFrame.value());
+        return data;
+    }
+
+    public record Data(
+            @Nullable Speed speed,
+            @Nullable Cadence cadence,
+            @Nullable Power humanPower) {
+
+        public Data(@Nullable Speed speed, @Nullable Cadence cadence, @Nullable Power humanPower, @Nullable Data oldData) {
+            this(
+                    speed != null ? speed : oldData != null ? oldData.speed() : null,
+                    cadence != null ? cadence : oldData != null ? oldData.cadence() : null,
+                    humanPower != null ? humanPower : oldData != null ? oldData.humanPower() : null);
+        }
+    }
+
+    private record DecodedFrame(int messageId, int value) {
+    }
+}

src/main/java/de/dennisguse/opentracks/sensors/driver/CyclingPowerBluetooth.java

@@ -18,14 +18,28 @@ public class CyclingPowerBluetooth implements BluetoothDriver.BluetoothParser<Cy
             new UUID(0x2A6300001000L, 0x800000805f9b34fbL)
     );
 
+    public static final List<ServiceMeasurementUUID> SUPPORTED_SERVICES = List.of(
+            CYCLING_POWER,
+            BoschEbikeParser.BOSCH_EBIKE
+    );
+
     @Override
     public List<ServiceMeasurementUUID> getServices() {
-        return List.of(CYCLING_POWER);
+        return SUPPORTED_SERVICES;
     }
 
     @Override
     public CyclingPowerBluetooth.Data parsePayload(@NonNull ServiceMeasurementUUID serviceMeasurementUUID, String sensorName, BluetoothGattCharacteristic characteristic) {
-        return parseCyclingPower(characteristic);
+        if (serviceMeasurementUUID.equals(CYCLING_POWER)) {
+            return parseCyclingPower(characteristic);
+        }
+        if (serviceMeasurementUUID.equals(BoschEbikeParser.BOSCH_EBIKE)) {
+            BoschEbikeParser.Data boschData = BoschEbikeParser.parse(characteristic.getValue());
+            if (boschData != null && boschData.humanPower() != null) {
+                return new Data(boschData.humanPower(), null);
+            }
+        }
+        return null;
     }
 
 

src/main/java/de/dennisguse/opentracks/settings/bluetooth/BluetoothLeCyclingPowerPreference.java

@@ -4,9 +4,6 @@ import android.content.Context;
 import android.util.AttributeSet;
 
 import androidx.preference.PreferenceDialogFragmentCompat;
-
-import java.util.List;
-
 import de.dennisguse.opentracks.sensors.driver.CyclingPowerBluetooth;
 
 public class BluetoothLeCyclingPowerPreference extends BluetoothLeSensorPreference {
@@ -29,6 +26,8 @@ public class BluetoothLeCyclingPowerPreference extends BluetoothLeSensorPreferen
 
     @Override
     public PreferenceDialogFragmentCompat createInstance() {
-        return BluetoothLeSensorPreference.BluetoothLeSensorPreferenceDialog.newInstance(getKey(), List.of(CyclingPowerBluetooth.CYCLING_POWER));
+        return BluetoothLeSensorPreference.BluetoothLeSensorPreferenceDialog.newInstance(
+                getKey(),
+                CyclingPowerBluetooth.SUPPORTED_SERVICES);
     }
-}
+}