L3G4200D.cpp

00001 #include "L3G4200D.h"
00002 
00003 L3G4200D::L3G4200D(PinName sda, PinName scl) : I2C_Sensor(sda, scl, L3G4200D_I2C_ADDRESS)
00004 {
00005     // Turns on the L3G4200D's gyro and places it in normal mode.
00006     // Normal power mode, all axes enabled (for detailed info see datasheet)
00007     
00008     //writeRegister(L3G4200D_CTRL_REG2, 0x05);               // control filter
00009     writeRegister(L3G4200D_CTRL_REG2, 0x00);            // highpass filter disabled
00010     writeRegister(L3G4200D_CTRL_REG3, 0x00);
00011     writeRegister(L3G4200D_CTRL_REG4, 0x20);            // sets acuracy to 2000 dps (degree per second)
00012     
00013     writeRegister(L3G4200D_REFERENCE, 0x00);
00014     //writeRegister(L3G4200D_STATUS_REG, 0x0F);
00015     
00016     writeRegister(L3G4200D_INT1_THS_XH, 0x2C); // TODO: WTF??
00017     writeRegister(L3G4200D_INT1_THS_XL, 0xA4);
00018     writeRegister(L3G4200D_INT1_THS_YH, 0x2C);
00019     writeRegister(L3G4200D_INT1_THS_YL, 0xA4);
00020     writeRegister(L3G4200D_INT1_THS_ZH, 0x2C);
00021     writeRegister(L3G4200D_INT1_THS_ZL, 0xA4);
00022     //writeRegister(L3G4200D_INT1_DURATION, 0x00);
00023     
00024     writeRegister(L3G4200D_CTRL_REG5, 0x00);            // deactivates the filters (only use one of these options)
00025     //writeRegister(L3G4200D_CTRL_REG5, 0x12);          // activates both high and low pass filters
00026     //writeRegister(L3G4200D_CTRL_REG5, 0x01);          // activates high pass filter
00027     
00028     writeRegister(L3G4200D_CTRL_REG1, 0x0F);            // starts Gyro measurement
00029     
00030     //calibrate(50, 0.01);
00031 }
00032 
00033 void L3G4200D::read()
00034 {
00035     readraw();                                          // read raw measurement data
00036     
00037     for (int i = 0; i < 3; i++)
00038             data[i] = (raw[i] - offset[i])*0.07;               // subtract offset from calibration and multiply unit factor (datasheet s.10)
00039 }
00040 
00041 int L3G4200D::readTemp()
00042 {
00043     return (short) readRegister(L3G4200D_OUT_TEMP);     // read the sensors register for the temperature
00044 }
00045 
00046 void L3G4200D::readraw()
00047 {
00048     char buffer[6];                                     // 8-Bit pieces of axis data
00049     
00050     readMultiRegister(L3G4200D_OUT_X_L | (1 << 7), buffer, 6); // read axis registers using I2C   // TODO: why?!   | (1 << 7)
00051     
00052     raw[0] = (short) (buffer[1] << 8 | buffer[0]);     // join 8-Bit pieces to 16-bit short integers
00053     raw[1] = (short) (buffer[3] << 8 | buffer[2]);
00054     raw[2] = (short) (buffer[5] << 8 | buffer[4]);
00055 }
00056 
00057 void L3G4200D::calibrate(int times, float separation_time)
00058 {
00059     // calibrate sensor with an average of count samples (result of calibration stored in offset[])
00060     float calib[3] = {0,0,0};                           // temporary array for the sum of calibration measurement
00061     
00062     for (int i = 0; i < times; i++) {                   // read 'times' times the data in a very short time
00063         readraw();
00064         for (int j = 0; j < 3; j++)
00065             calib[j] += raw[j];
00066         wait(separation_time);
00067     }
00068     
00069     for (int i = 0; i < 3; i++)
00070         offset[i] = calib[i]/times;                     // take the average of the calibration measurements
00071 }