//Arduino 1.0+ Compatible only

// Code to retrieve heartrate information from the Polar Heart Rate Monitor Interface via I2C
// Part: http://www.sparkfun.com/products/8661
// Article:  http://bildr.org/2011/08/heartrate-arduino/

#include <Wire.h>

#define HRMI_I2C_ADDR      127
#define HRMI_HR_ALG        1   // 1= average sample, 0 = raw sample

void setup(){
  setupHeartMonitor(HRMI_HR_ALG);
  Serial.begin(9600);
  
  Wire.begin();
}

void loop()
{
  int heartRate = getHeartRate();
//  Serial.println(heartRate);
  byte heartRateByte=(byte)heartRate;
  Serial.println(heartRateByte);
  Wire.beginTransmission(5);
  Wire.write(heartRateByte);
  Wire.endTransmission();
 /*
  while(Serial.available())
  {
    int r = Serial.read();
    if(r > 0)
    {
      Wire.beginTransmission(5);
      Wire.write(r);
      Wire.endTransmission();
    }
    else if(r == 0)
    {
      Wire.beginTransmission(5);
      Wire.write(0);
      Wire.endTransmission();
    }
  }
 */
  delay(1000); //just here to slow down the checking to once a second
}

void setupHeartMonitor(int type){
  //setup the heartrate monitor
  Wire.begin();
  writeRegister(HRMI_I2C_ADDR, 0x53, type); // Configure the HRMI with the requested algorithm mode
}

int getHeartRate(){
  //get and return heart rate
  //returns 0 if we couldnt get the heart rate
  byte i2cRspArray[3]; // I2C response array
  i2cRspArray[2] = 0;

  writeRegister(HRMI_I2C_ADDR,  0x47, 0x1); // Request a set of heart rate values 

  if (hrmiGetData(127, 3, i2cRspArray)) {
    return i2cRspArray[2];
  }
  else{
    return 0;
  }
}

void writeRegister(int deviceAddress, byte address, byte val) {
  //I2C command to send data to a specific address on the device
  Wire.beginTransmission(deviceAddress); // start transmission to device 
  Wire.write(address);       // send register address
  Wire.write(val);         // send value to write
  Wire.endTransmission();     // end transmission
}

boolean hrmiGetData(byte addr, byte numBytes, byte* dataArray){
  //Get data from heart rate monitor and fill dataArray byte with response
  //Returns true if it was able to get it, false if not
  Wire.requestFrom(addr, numBytes);
  if (Wire.available()) {

    for (int i=0; i<numBytes; i++){
      dataArray[i] = Wire.read();
    }

    return true;
  }
  else{
    return false;
  }
}