File content as of revision 0:9a72d42c0da3:

/* This file is part of the Razor AHRS Firmware */
#include "Razor_AHRS.h"

// I2C code to read the sensors

// Sensor I2C addresses
#define ACCEL_READ  0xA7
#define ACCEL_WRITE 0xA6
#define MAGN_WRITE  0x3C 
#define MAGN_READ   0x3D 
#define GYRO_WRITE  0xD0
#define GYRO_READ   0xD1

void IMU::I2C_Init()
{
  Wire.frequency(100000);
}

void IMU::Accel_Init()
{
  char tx[2];
  tx[0] = 0x2D; // Power register
  tx[1] = 0x08; // Power register
  Wire.write(ACCEL_WRITE, tx, 2);
  wait_ms(5);
  tx[0] = 0x31; // Data format register
  tx[1] = 0x08; // Set to full resolution
  Wire.write(ACCEL_WRITE, tx, 2);
  wait_ms(5);
  
  // Because our main loop runs at 50Hz we adjust the output data rate to 50Hz (25Hz bandwidth)
  tx[0] = 0x2C;  // Rate
  tx[1] = 0x09;  // Set to 50Hz, normal operation
  Wire.write(ACCEL_WRITE, tx, 2);
  wait_ms(5);
}

// Reads x, y and z accelerometer registers
void IMU::Read_Accel()
{
  char buff[6];
  char tx = 0x32;  // Send address to read from
 
  Wire.write(ACCEL_WRITE, &tx, 1);
  
  if (Wire.read(ACCEL_READ, buff, 6) == 0) // All bytes received?
  {
    // No multiply by -1 for coordinate system transformation here, because of double negation:
    // We want the gravity vector, which is negated acceleration vector.
    accel[0] = (int)buff[3] << 8 | (int)buff[2]; // X axis (internal sensor y axis)
    accel[1] = (int)buff[1] << 8 | (int)buff[0]; // Y axis (internal sensor x axis)
    accel[2] = (int)buff[5] << 8 | (int)buff[4]; // Z axis (internal sensor z axis)
  }
  else
  {
    num_accel_errors++;
    if (output_errors) pc.printf("!ERR: reading accelerometer" NEW_LINE);
  }
}

void IMU::Magn_Init()
{
  char tx[2];
  tx[0] = 0x02; // Mode
  tx[1] = 0x00; // Set continuous mode (default 10Hz)
  Wire.write(MAGN_WRITE, tx, 2);
  wait_ms(5);

  tx[0] = 0x00; // CONFIG_A 
  tx[1] = 0x18; // Set 50Hz
  Wire.write(MAGN_WRITE, tx, 2);
  wait_ms(5);
}

void IMU::Read_Magn()
{
  char buff[6];
  char tx = 0x03;  // Send address to read from 

  Wire.write(MAGN_WRITE, &tx, 1);
  
  if (Wire.read(MAGN_READ, buff, 6) == 0)  // All bytes received?
  {
// 9DOF Razor IMU SEN-10125 using HMC5843 magnetometer
#if HW__VERSION_CODE == 10125
    // MSB byte first, then LSB; X, Y, Z
    magnetom[0] = -1 * (((int) buff[2]) << 8) | buff[3];  // X axis (internal sensor -y axis)
    magnetom[1] = -1 * (((int) buff[0]) << 8) | buff[1];  // Y axis (internal sensor -x axis)
    magnetom[2] = -1 * (((int) buff[4]) << 8) | buff[5];  // Z axis (internal sensor -z axis)
// 9DOF Razor IMU SEN-10736 using HMC5883L magnetometer
#elif HW__VERSION_CODE == 10736
    // MSB byte first, then LSB; Y and Z reversed: X, Z, Y
    magnetom[0] = -1 * (((int) buff[4]) << 8) | buff[5];  // X axis (internal sensor -y axis)
    magnetom[1] = -1 * (((int) buff[0]) << 8) | buff[1];  // Y axis (internal sensor -x axis)
    magnetom[2] = -1 * (((int) buff[2]) << 8) | buff[3];  // Z axis (internal sensor -z axis)
// 9DOF Sensor Stick SEN-10183 and SEN-10321 using HMC5843 magnetometer
#elif (HW__VERSION_CODE == 10183) || (HW__VERSION_CODE == 10321)
    // MSB byte first, then LSB; X, Y, Z
    magnetom[0] = (((int) buff[0]) << 8) | buff[1];       // X axis (internal sensor x axis)
    magnetom[1] = -1 * (((int) buff[2]) << 8) | buff[3];  // Y axis (internal sensor -y axis)
    magnetom[2] = -1 * (((int) buff[4]) << 8) | buff[5];  // Z axis (internal sensor -z axis)
// 9DOF Sensor Stick SEN-10724 using HMC5883L magnetometer
#elif HW__VERSION_CODE == 10724
    // MSB byte first, then LSB; Y and Z reversed: X, Z, Y
    magnetom[0] =  1 * ((int)buff[0] << 8 | (int)buff[1]); // X axis (internal sensor x axis)
    magnetom[1] = -1 * ((int)buff[4] << 8 | (int)buff[5]); // Y axis (internal sensor -y axis)
    magnetom[2] = -1 * ((int)buff[2] << 8 | (int)buff[3]); // Z axis (internal sensor -z axis)
#endif
  }
  else
  {
    num_magn_errors++;
    if (output_errors) pc.printf("!ERR: reading magnetometer" NEW_LINE);
  }
}

void IMU::Gyro_Init()
{
  char tx[2];
  
  // Power up reset defaults
  tx[0] = 0x3E; // Power management
  tx[1] = 0x80; // ?
  Wire.write(GYRO_WRITE, tx, 2);
  wait_ms(5);
  
  // Select full-scale range of the gyro sensors
  // Set LP filter bandwidth to 42Hz
  tx[0] = 0x16; // 
  tx[1] = 0x1B; // DLPF_CFG = 3, FS_SEL = 3
  Wire.write(GYRO_WRITE, tx, 2);
  wait_ms(5);
  
  // Set sample rato to 50Hz
  tx[0] = 0x15; //
  tx[1] = 0x0A; //  SMPLRT_DIV = 10 (50Hz)
  Wire.write(GYRO_WRITE, tx, 2);
  wait_ms(5);

  // Set clock to PLL with z gyro reference
  tx[0] = 0x3E;
  tx[1] = 0x00;
  Wire.write(GYRO_WRITE, tx, 2);
  wait_ms(5);
}

// Reads x, y and z gyroscope registers
void IMU::Read_Gyro()
{
  char buff[6];
  char tx = 0x1D; // Sends address to read from
  
  Wire.write(GYRO_WRITE, &tx, 1);
  
  if (Wire.read(GYRO_READ, buff, 6) == 0)  // All bytes received?
  {
    gyro[0] = -1 * ((int)buff[2] << 8 | (int)buff[3]);   // X axis (internal sensor -y axis)
    gyro[1] = -1 * ((int)buff[0] << 8 | (int)buff[1]);   // Y axis (internal sensor -x axis)
    gyro[2] = -1 * ((int)buff[4] << 8 | (int)buff[5]);   // Z axis (internal sensor -z axis)
  }
  else
  {
    num_gyro_errors++;
    if (output_errors) pc.printf("!ERR: reading gyroscope" NEW_LINE);
  }
}