diff --git a/MyTracks/src/com/google/android/apps/mytracks/services/sensors/PolarMessageParser.java b/MyTracks/src/com/google/android/apps/mytracks/services/sensors/PolarMessageParser.java new file mode 100644 index 000000000..ee11135a7 --- /dev/null +++ b/MyTracks/src/com/google/android/apps/mytracks/services/sensors/PolarMessageParser.java @@ -0,0 +1,130 @@ +/* + * Copyright 2011 Google Inc. + * + * Licensed under the Apache License, Version 2.0 (the "License"); you may not + * use this file except in compliance with the License. You may obtain a copy of + * the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the + * License for the specific language governing permissions and limitations under + * the License. + */ +package com.google.android.apps.mytracks.services.sensors; + +import android.util.Log; + +import com.google.android.apps.mytracks.Constants; +import com.google.android.apps.mytracks.content.Sensor; + +/** + * An implementation of a SensorData parser for Polar Wearlink Bluetooth HRM. + * + * @author John R. Gerthoffer + */ +public class PolarMessageParser implements MessageParser { + // Last Heart Rate value storage (in case of corrupt buffer) + private int lastHeartRate = 0; + + @Override + public Sensor.SensorDataSet parseBuffer(byte[] buffer) { + StringBuilder sb = new StringBuilder(); + int heartRate = 0; + + // Due to a memory inconsistency issue, the packet does not always start at buffer[0]. + // While it works stepping thru in debug mode, it is not consistent when running real-time. + // Note: After changing the BluetoothConnectionManager to pass a copy of 'buffer', + // the problem was resolved! Passing a buffer copy in threaded comm's is typical in my experience. + + // Minimum length Polar packets is 8, so stop search 8 bytes before buffer ends. + heartRate = lastHeartRate; // Default to use last value. (If our buffer is corrupted). + for (int i = 0; i < buffer.length - 8; i++) { + boolean bHdrOK = ((buffer[i] & 0xFF) == 0xFE); + boolean bChkOK = ((buffer[i+2] & 0xFF) == (0xFF - (buffer[i+1] & 0xFF))); + boolean bSeqOK = ((buffer[i+3] & 0xFF) < 16); + boolean bStatusOK = ((buffer[i+4] & 0xFF) > 128); // I've seen 0xF1 or 0xE1. + + if (bHdrOK && bChkOK && bSeqOK && bStatusOK) { + heartRate = buffer[i + 5] & 0xFF; + lastHeartRate = heartRate; // Remember good value for next time. + break; // Let's go store our data. + } + } + + // Heart Rate + Sensor.SensorData.Builder b = Sensor.SensorData.newBuilder() + .setValue(heartRate) + .setState(Sensor.SensorState.SENDING); + + Sensor.SensorDataSet sds = + Sensor.SensorDataSet.newBuilder() + .setCreationTime(System.currentTimeMillis()) + .setHeartRate(b) + .build(); + + return sds; + } + + /** + * Applies packet validation rule to buffer + * Parsing rule for a good Polar HRM packet; + * boolean goodHdr = ((buffer[0] & 0xFF) == 0xFE); + * boolean goodChk = ((buffer[2] & 0xFF) == (0xFF - (buffer[1] & 0xFF))); + * goodPacket = goodHdr && goodChk; + * + * @param an array of bytes to parse + * @return whether buffer has a valid packet starting at index zero + */ + @Override + public boolean isValid(byte[] buffer) { + /** + * Polar Bluetooth Wearlink packet example; + * Hdr Len Chk Seq Status HeartRate RRInterval_16-bits + * FE 08 F7 06 F1 48 03 64 + * where Hdr always = 0xFE, Chk = 0xFF - Len + * + * Additional packet examples; + * FE 08 F7 06 F1 48 03 64 + * FE 0A F5 06 F1 48 03 64 03 70 + */ + boolean goodHdr = ((buffer[0] & 0xFF) == 0xFE); + boolean goodChk = ((buffer[2] & 0xFF) == (0xFF - (buffer[1] & 0xFF))); + return goodHdr && goodChk; + } + + /** + * Polar uses variable packet sizes; 8, 10, 12, 14 and rarely 16. + * The most frequent are 8 and 10. + * We will wait for 16 bytes. + * This way, we are assured of getting one good one. + * + * @return the size of buffer needed to parse a good packet + */ + @Override + public int getFrameSize() { + return 16; + } + + /** + * Searches buffer for the beginning of a valid packet. + * Parsing rule for a good Polar HRM packet; + * boolean goodHdr = ((buffer[0] & 0xFF) == 0xFE); + * boolean goodChk = ((buffer[2] & 0xFF) == (0xFF - (buffer[1] & 0xFF))); + * goodPacket = goodHdr && goodChk; + * + * @param an array of bytes to parse + */ + @Override + public int findNextAlignment(byte[] buffer) { + // Minimum length Polar packets is 8, so stop search 8 bytes before buffer ends. + for (int i = 0; i < buffer.length - 8; i++) { + if (((buffer[i] & 0xFF) == 0xFE) && ((buffer[i+2] & 0xFF) == (0xFF - (buffer[i+1] & 0xFF)))) { + return i; + } + } + return -1; + } +}