gyro.py

#!/usr/bin/python

from time import sleep
#import smbus to access i2c port
import smbus
import string

#converts 16 bit two's compliment reading to signed int
def getSignedNumber(number):
    if number & (1 << 15):
        return number | ~65535
    else:
        return number & 65535

#open /dev/i2c-1
i2c_bus=smbus.SMBus(1)
#i2c slave address of the L3G4200D
i2c_address=0x69

#initialise the L3G4200D

#normal mode and all axes on to control reg1
i2c_bus.write_byte_data(i2c_address,0x20,0x0F)
#full 2000dps to control reg4
i2c_bus.write_byte_data(i2c_address,0x23,0x20)

#read lower and upper bytes, combine and display
while True:


                i2c_bus.write_byte(i2c_address,0x28)
                X_L = i2c_bus.read_byte(i2c_address)
                i2c_bus.write_byte(i2c_address,0x29)
                X_H = i2c_bus.read_byte(i2c_address)
                X = X_H << 8 | X_L

                i2c_bus.write_byte(i2c_address,0x2A)
                Y_L = i2c_bus.read_byte(i2c_address)
                i2c_bus.write_byte(i2c_address,0x2B)
                Y_H = i2c_bus.read_byte(i2c_address)
                Y = Y_H << 8 | Y_L

                i2c_bus.write_byte(i2c_address,0x2C)
                Z_L = i2c_bus.read_byte(i2c_address)
                i2c_bus.write_byte(i2c_address,0x2D)
                Z_H = i2c_bus.read_byte(i2c_address)
                Z = Z_H << 8 | Z_L

                X = getSignedNumber(X)
                Y = getSignedNumber(Y)
                Z = getSignedNumber(Z)

                print string.rjust(`X`, 10),
                print string.rjust(`Y`, 10),
                print string.rjust(`Z`, 10)
                sleep(0.02)