NOT FINISHED YET!!! My first try to get a self built fully working Quadrocopter based on an mbed, a self built frame and some other more or less cheap parts.
Sensors/Comp/HMC5883.cpp
- Committer:
- maetugr
- Date:
- 2012-10-29
- Revision:
- 15:753c5d6a63b3
- Parent:
- 14:cf260677ecde
- Child:
- 17:e096e85f6c36
File content as of revision 15:753c5d6a63b3:
#include "mbed.h" #include "HMC5883.h" HMC5883::HMC5883(PinName sda, PinName scl) : i2c(sda, scl), local("local") { i2c.frequency(400000); // TODO: zu testen!! // load calibration values FILE *fp = fopen("/local/compass.txt", "r"); for(int i = 0; i < 3; i++) fscanf(fp, "%f", &scale[i]); for(int i = 0; i < 3; i++) fscanf(fp, "%f", &offset[i]); fclose(fp); // initialize HMC5883 for scaling writeReg(HMC5883_CONF_REG_A, 0x19); // 8 samples, 75Hz output, test mode for scaling! writeReg(HMC5883_CONF_REG_B, 0x20); // Gain for +- 1.3 gauss (earth compass ~0.6 gauss) writeReg(HMC5883_MODE_REG, 0x00); // continuous measurement-mode /* (not important, just from data sheet) // Scaling with testmode for(int j = 0; j < 3; j++) // set all scales to 1 first so the measurement for scaling is not already scaled scale[j] = 1; int data50[3] = {0,0,0}; // to save the 50 measurements for(int i = 0; i < 50; i++) // measure 50 times the testmode value to get an average { read(); for(int j = 0; j < 3; j++) data50[j] += data[j]; } scale[0] = (1.16 * 1090)/(data50[0]/50.0); // value that it should be with selftest of 1.1 Gauss * 1090 LSB/Gauss / the value it is scale[1] = (1.16 * 1090)/(data50[1]/50.0); scale[2] = (1.08 * 1090)/(data50[2]/50.0); */ // set normal mode writeReg(HMC5883_CONF_REG_A, 0x78); // 8 samples, 75Hz output, normal mode } void HMC5883::read() { readraw(); for(int i = 0; i < 3; i++) data[i] = scale[i] * (float)(raw[i]) + offset[i]; } void HMC5883::calibrate(int s) { Timer calibrate_timer; calibrate_timer.start(); while(calibrate_timer.read() < s) { readraw(); for(int i = 0; i < 3; i++) { Min[i]= Min[i] < raw[i] ? Min[i] : raw[i]; Max[i]= Max[i] > raw[i] ? Max[i] : raw[i]; //Scale und Offset aus gesammelten Min Max Werten berechnen //Die neue Untere und obere Grenze bilden -1 und +1 scale[i]= 2000 / (float)(Max[i]-Min[i]); offset[i]= 1000 - (float)(Max[i]) * scale[i]; } } // save values FILE *fp = fopen("/local/compass.txt", "w"); for(int i = 0; i < 3; i++) fprintf(fp, "%f\r\n", scale[i]); for(int i = 0; i < 3; i++) fprintf(fp, "%f\r\n", offset[i]); fclose(fp); } void HMC5883::readraw() { char buffer[6]; readMultiReg(HMC5883_DATA_OUT_X_MSB, buffer, 6); // read the raw data from I2C // join MSB and LSB of X, Z and Y (yes, order is so stupid, see datasheet) raw[0] = (short) (buffer[0] << 8 | buffer[1]); raw[1] = (short) (buffer[4] << 8 | buffer[5]); raw[2] = (short) (buffer[2] << 8 | buffer[3]); } void HMC5883::writeReg(char address, char data){ char tx[2]; tx[0] = address; tx[1] = data; i2c.write(I2CADR_W(HMC5883_ADDRESS), tx, 2); } void HMC5883::readMultiReg(char address, char* output, int size) { i2c.write(I2CADR_W(HMC5883_ADDRESS), &address, 1, true); //tell it where to read from i2c.read(I2CADR_R(HMC5883_ADDRESS) , output, size, true); //tell it where to store the data read } float HMC5883::get_angle() { #define Rad2Deg 57.295779513082320876798154814105 float Heading; Heading = Rad2Deg * atan2(data[0],data[1]); Heading += 1.367; //bei Ost-Deklination += DecAngle, bei West-Deklination -= DecAngle //Missweisung = Winkel zwischen geographischer und magnetischer Nordrichtung //Bern ca. 1.367 Grad Ost //http://www.swisstopo.admin.ch/internet/swisstopo/de/home/apps/calc/declination.html if(Heading < 0) Heading += 360; // minimum 0 degree if(Heading > 360) Heading -= 360; // maximum 360 degree return Heading; }