#!/usr/bin/python
# HMC5883

import smbus
import time

address = 0x1E

# Get I2C bus
bus = smbus.SMBus(1)

# Select configuration register A, 0x00
# 0x70 == 8-average, Data output rate = 15 Hz, Normal measurement configuration
bus.write_byte_data(address, 0x00, 0x70)

# Select configuration register B, 0x01
# 0xA0 == Gain=5 (440 LSb/Gauss)
bus.write_byte_data(address, 0x01, 0xA0)

# Select mode register, 0x02
# 0x00 == Continuous measurement mode
bus.write_byte_data(address, 0x02, 0x00)

time.sleep(0.5)

# Read data back from 0x03, 6 bytes
# X-Axis MSB, X-Axis LSB, Z-Axis MSB, Z-Axis LSB, Y-Axis MSB, Y-Axis LSB
data = bus.read_i2c_block_data(address, 0x03, 6)

# Convert the data
xMag = data[0] * 256 + data[1]
if xMag > 32767 :
	xMag -= 65536

zMag = data[2] * 256 + data[3]
if zMag > 32767 :
	zMag -= 65536

yMag = data[4] * 256 + data[5]
if yMag > 32767 :
	yMag -= 65536

# Output data to screen
print "Magnetic field in X-Axis : %d" %xMag
print "Magnetic field in Y-Axis : %d" %yMag
print "Magnetic field in Z-Axis : %d" %zMag