// I2C HMC6352 compass heading (sparkfun breakout) 
// by BARRAGAN (http://barraganstudio.com) 

 
#include <TwoWire.h> 
 
int compassAddress = 0x42 >> 1;  // From datasheet compass address is 0x42 
                                 // shift the address 1 bit right, the Wire library only needs the 7 
                                 // most significant bits for the address 
int reading = 0; 
 
void setup() 
{ 
  Wire.begin();                // join i2c bus (address optional for master) 
  Serial.begin(9600);          // start serial communication at 9600bps 
  pinMode(48, OUTPUT); 
  digitalWrite(48, HIGH); 
} 
  
void loop() 
{ 
  // step 1: instruct sensor to read echoes 
  Wire.beginTransmission(compassAddress); // transmit to device 
                              // the address specified in the datasheet is 66 (0x42) 
                              // but i2c adressing uses the high 7 bits so it's 33 
  Wire.send('A');             // command sensor to measure angle  
  Wire.endTransmission();     // stop transmitting 
 
  // step 2: wait for readings to happen 
  delay(10);                   // datasheet suggests at least 6000 microseconds 
  
  // step 3: request reading from sensor 
  Wire.requestFrom(compassAddress, 2);    // request 2 bytes from slave device #33 
 
  // step 4: receive reading from sensor 
  if(2 <= Wire.available())    // if two bytes were received 
  { 
    reading = Wire.receive();  // receive high byte (overwrites previous reading) 
    reading = reading << 8;    // shift high byte to be high 8 bits 
    reading += Wire.receive(); // receive low byte as lower 8 bits 
    reading /= 10; 
    Serial.println(reading);   // print the reading 
  } 
 
  delay(500);                  // wait for half a second 
}