SparkFun: ITG-3200,Triple-Axis Gyro

Overview
The ADXL335 is a three-axis accelerometer that can be purchased from SparkFun. The datasheet describes it:

''The ITG-3200 is the world’s first single-chip, digital-output, 3-axis MEMS gyro IC optimized for gaming, 3D mice, and 3D remote control applications. The part features enhanced bias and sensitivity temperature stability, reducing the need for user calibration. Low frequency noise is lower than previous generation devices, simplifying application development and making for more-responsive remote controls.''

Inputs and Outputs
The ITG-3200 takes a supply voltage (Vs) of 1.8-3.6 V. The analog outputs are scaled proportionally to the supply voltage; at Vs = 3.6 V, the output will change by 2x for the same acceleration as compared to Vs = 1.8 V. Although the output sensitivity is scaled proportionally to the input voltage, noise is not, so higher supply voltages are advisable to reduce the impact of noise.

At all supply voltages, 0 g acceleration corresponds to an output voltage of Vs/2. At Vs = 3.6 V, the datasheet specs the typical sensitivity at 360 mV / g, with g as standard gravitational acceleration.

Bone Usage
Because the ITG-3200 has and I2C port, data can be read into the Bone via the I2C buss pins. One sets of I2C buss pins are required, for the X, Y, Z, and temperature outputs on the gyro. Here we will use the ITG300.h (This header also imports the i2c-dev.h and errno.h automatically, these are necessary to poll the device later on). See the picture on the right for an example wiring configuration.

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Note: There are two unpopulated resistors on the I2C lines, these can be added later by the customer if desired..

Sample C Code
The code shown below is sample code to demonstrate reading the registers via I2C and using the library.

/* * MiniProject02.c * * Created on: Sep 20, 2012 *     Author: Ruffin White */


 * 1) include "Header.h"
 * 2) include 
 * 3) include 
 * 4) include 
 * 5) include 
 * 6) include 
 * 7) include 
 * 8) include 
 * 9) include "ITG-3200.h"

int loop=1;

void signal_handler(int sig) {	printf( "Ctrl-C pressed, cleaning up and exiting..\n" ); loop = 0; }

int main(int argc, char** argv){

//variable declarations struct pollfd fdset[1]; int nfds = 1; int timeout = 100; int rc; char* buf[MAX_BUF]; int gpio1, gpio2; int gpio1_fd, gpio2_fd; int gpio2_value = 0; int pattern =0; int value =0;

int freq = 10; int duty = 25;

int gyroID, gyroTemp, gyroX, gyroY, gyroZ;

// I2C Variables char *end; int res, i2cbus, address, size, file; int daddress;

//check that at least two arguments are passed in	if(argc < 4){ printf("Usage: %s   \n", argv[0]); printf("polls input-gpio, and writes value to output-gpio\n"); fflush(stdout); return 1; }

//set signal handler for Ctrl + C	if (signal(SIGINT, signal_handler) == SIG_ERR) printf("\ncan't catch SIGINT\n");

//assign gpio values gpio1 = atoi(argv[1]); gpio2 = atoi(argv[2]);

//assign I2C values i2cbus  = atoi(argv[3]); address = ITG3200_I2C_ADDRESS; file = initialize(i2cbus, address);

//argument 1 will be input export_gpio(gpio1); set_gpio_direction(gpio1, "in"); set_gpio_edge(gpio1, "falling"); gpio1_fd = gpio_fd_open(gpio1);

//argument 2 will be output export_gpio(gpio2); set_gpio_direction(gpio2, "out"); set_gpio_value(gpio2, gpio2_value); gpio2_fd = gpio_fd_open(gpio2);

set_mux_value("gpmc_a2",6);

while(loop){ memset((void*)fdset, 0, sizeof(fdset));

fdset[0].fd = gpio1_fd; fdset[0].events = POLLPRI;

rc = poll(fdset, nfds, timeout);

if (rc < 0){ printf("\npoll failed!\n"); }

if (rc == 0){ printf("."); }

if((fdset[0].revents & POLLPRI) == POLLPRI) { read(fdset[0].fd, buf, MAX_BUF); printf("interrupt value=%c\n", buf[0]); pattern++; if(pattern == 4){ pattern = 0; }		}

switch(pattern){

// blink led case 0: printf("Case 0\n"); value = read_ain("ain6"); printf("Voltage: %d\n",value); set_pwm("ehrpwm.1:0",10,25); if(gpio2_value){ gpio2_value = 0; }				else{ gpio2_value = 1; }				set_gpio_value(gpio2, gpio2_value); break;

//PWM output case 1:

gyroID = readWhoAmI(file);

printf("gyroID: 0x%02x (%d)\n", gyroID, gyroID); break;

//Read Gyro Temperature case 2: printf("Case 2\n");

gyroTemp = readTemp(file);

printf("gyroTemp: 0x%02x (%d)\n", gyroTemp, gyroTemp); break;

//Read Gyro XYZ case 3: printf("Case 3\n");

gyroX = readX(file); gyroY = readY(file); gyroZ = readZ(file);

printf("gyroX: 0x%02x (%d)\n", gyroX, gyroX); printf("gyroY: 0x%02x (%d)\n", gyroY, gyroY); printf("gyroZ: 0x%02x (%d)\n", gyroZ, gyroZ); break;

default: break; }		}	close(file); gpio_fd_close(gpio1_fd); gpio_fd_close(gpio2_fd); unexport_gpio(gpio1); unexport_gpio(gpio2); fflush(stdout); return 0; }

Header File
The code shown below is header file code used for using the gyro.

/* * ITG3200.h * * Created on: Sep 20, 2012 *     Author: Ruffin White */

/** * Includes */
 * 1) include 
 * 2) include "i2c-dev.h"

/** * Defines */
 * 1) define ITG3200_I2C_ADDRESS 0x69 //7-bit address

//--- // Registers //---
 * 1) define WHO_AM_I_REG   0x00
 * 2) define SMPLRT_DIV_REG 0x15
 * 3) define DLPF_FS_REG    0x16
 * 4) define INT_CFG_REG    0x17
 * 5) define INT_STATUS     0x1A
 * 6) define TEMP_OUT_H_REG 0x1B
 * 7) define TEMP_OUT_L_REG 0x1C
 * 8) define GYRO_XOUT_H_REG 0x1D
 * 9) define GYRO_XOUT_L_REG 0x1E
 * 10) define GYRO_YOUT_H_REG 0x1F
 * 11) define GYRO_YOUT_L_REG 0x20
 * 12) define GYRO_ZOUT_H_REG 0x21
 * 13) define GYRO_ZOUT_L_REG 0x22
 * 14) define PWR_MGM_REG    0x3E

// // Low Pass Filter Bandwidths //
 * 1) define LPFBW_256HZ 0x00
 * 2) define LPFBW_188HZ 0x01
 * 3) define LPFBW_98HZ 0x02
 * 4) define LPFBW_42HZ 0x03
 * 5) define LPFBW_20HZ 0x04
 * 6) define LPFBW_10HZ 0x05
 * 7) define LPFBW_5HZ  0x06

//--- // Offsets //--- int TEMP_OUT_OFFSET; int GYRO_XOUT_OFFSET; int GYRO_YOUT_OFFSET; int GYRO_ZOUT_OFFSET;

// // Read Functions //

//This function is used to initialize the gyroscope. The function returns the -errno if an error accrues. int initialize(int i2cbus, int address){

char filename[20]; int file; sprintf(filename, "/dev/i2c-%d", i2cbus); file = open(filename, O_RDWR); if (file<0) { return -errno; }

if (ioctl(file, I2C_SLAVE, address) < 0) { return -errno; }	return file;

}

//This function is used to read the WHO_AM_I_REG of the gyroscope. //Usage: int gyroID = readWhoAmI; int readWhoAmI(int file) { int data=0; data = i2c_smbus_read_byte_data(file, WHO_AM_I_REG);

return data; }

//This function is used to read the temperature of the gyroscope. //Usage: int gyroTemp = readTemp; int readTemp(int file) { int data=0; data = i2c_smbus_read_byte_data(file, TEMP_OUT_H_REG)<<8; data |= i2c_smbus_read_byte_data(file, TEMP_OUT_L_REG);

return data; }

//This function is used to read the X-Axis rate of the gyroscope. The function returns the ADC value from the Gyroscope //NOTE: This value is NOT in degrees per second. //Usage: int xRate = readX; int readX(int file) { int data=0; data = i2c_smbus_read_byte_data(file, GYRO_XOUT_H_REG)<<8; data |= i2c_smbus_read_byte_data(file, GYRO_XOUT_L_REG);

return data; }

//This function is used to read the Y-Axis rate of the gyroscope. The function returns the ADC value from the Gyroscope //NOTE: This value is NOT in degrees per second. //Usage: int yRate = readY; int readY(int file) { int data=0; data = i2c_smbus_read_byte_data(file, GYRO_YOUT_H_REG)<<8; data |= i2c_smbus_read_byte_data(file, GYRO_YOUT_L_REG);

return data; }

//This function is used to read the Z-Axis rate of the gyroscope. The function returns the ADC value from the Gyroscope //NOTE: This value is NOT in degrees per second. //Usage: int zRate = readZ; int readZ(int file) { int data=0; data = i2c_smbus_read_byte_data(file, GYRO_ZOUT_H_REG)<<8; data |= i2c_smbus_read_byte_data(file, GYRO_ZOUT_L_REG);

return data; }

Features
Digital-output X-, Y-, and Z-Axis angular rate sensors (gyros) on one integrated circuit Digitally-programmable low-pass filter Low 6.5mA operating current consumption for long battery life Wide VDD supply voltage range of 2.1V to 3.6V Standby current: 5μA Digital-output temperature sensor Fast Mode I2C (400kHz) serial interface Optional external clock inputs of 32.768kHz or 19.2MHz to synchronize with system clock Pins broken out to a breadboard friendly 7-pin 0.1" pitch header

Dimensions
0.70 x 0.55" (17.78 x 13.97mm)

Documents
Schematic

Eagle Files

Quickstart Guide

ITG-3200 Datasheet

Code (ATmega328)

Example