I love the little Sparkfun Pro Micro 5V. I loaded MultiWii 2.3 onto it. I have an MPU6050 and burned out my HMC5883 magnetometer. I couldnt find an HMC5883 so resorted to the China Junk QMC5883 which they claim is under license from Honeywell. Great, but it is not the same chip.
I found some code on Arduino which gets me x,y,z out of the sensor but it is about 100 x magnitude compared to the Honeywell HMC5883.
The problem is how do I calibrate it and scale the values in MultiWii? I used the QMC5883 library examples and got 6 values for calibration, but when I try to use their compass.setCalibration(x, x, y, y, z, z) function, I get an error that says no function setCalibration(int, int, int, int, int). That’s right, it seems to expect 5 integer values and not 6. This is why I hate Chinese knockoff junk even if it is licensed.
Here’s the code from MultiWii where it gets the magnetometer data.
// ************************************************************************************************************
// I2C Compass HMC5883
// ************************************************************************************************************
// I2C adress: 0x3C (8bit) 0x1E (7bit)
// ************************************************************************************************************
#if defined(HMC5883)
#define HMC58X3_R_CONFA 0
#define HMC58X3_R_CONFB 1
#define HMC58X3_R_MODE 2
#define HMC58X3_X_SELF_TEST_GAUSS (+1.16) //!< X axis level when bias current is applied.
#define HMC58X3_Y_SELF_TEST_GAUSS (+1.16) //!< Y axis level when bias current is applied.
#define HMC58X3_Z_SELF_TEST_GAUSS (+1.08) //!< Y axis level when bias current is applied.
#define SELF_TEST_LOW_LIMIT (243.0/390.0) //!< Low limit when gain is 5.
#define SELF_TEST_HIGH_LIMIT (575.0/390.0) //!< High limit when gain is 5.
#define HMC_POS_BIAS 1
#define HMC_NEG_BIAS 2
#define MAG_ADDRESS 0x0D//0x1E
#define MAG_DATA_REGISTER 0x00//0x03
void Mag_init() {
int32_t xyz_total[3]={0,0,0}; // 32 bit totals so they won't overflow.
bool bret=true; // Error indicator
delay(50); //Wait before start
i2c_writeReg(MAG_ADDRESS, HMC58X3_R_CONFA, 0x010 + HMC_POS_BIAS); // Reg A DOR=0x010 + MS1,MS0 set to pos bias
// Note that the very first measurement after a gain change maintains the same gain as the previous setting.
// The new gain setting is effective from the second measurement and on.
i2c_writeReg(MAG_ADDRESS, HMC58X3_R_CONFB, 2 << 5); //Set the Gain
i2c_writeReg(MAG_ADDRESS,HMC58X3_R_MODE, 1);
delay(100);
getADC(); //Get one sample, and discard it
for (uint8_t i=0; i<10; i++) { //Collect 10 samples
i2c_writeReg(MAG_ADDRESS,HMC58X3_R_MODE, 1);
delay(100);
getADC(); // Get the raw values in case the scales have already been changed.
// Since the measurements are noisy, they should be averaged rather than taking the max.
xyz_total[0]+=imu.magADC[0];
xyz_total[1]+=imu.magADC[1];
xyz_total[2]+=imu.magADC[2];
// Detect saturation.
if (-(1<<12) >= min(imu.magADC[0],min(imu.magADC[1],imu.magADC[2]))) {
bret=false;
break; // Breaks out of the for loop. No sense in continuing if we saturated.
}
}
// Apply the negative bias. (Same gain)
i2c_writeReg(MAG_ADDRESS,HMC58X3_R_CONFA, 0x010 + HMC_NEG_BIAS); // Reg A DOR=0x010 + MS1,MS0 set to negative bias.
for (uint8_t i=0; i<10; i++) {
i2c_writeReg(MAG_ADDRESS,HMC58X3_R_MODE, 1);
delay(100);
getADC(); // Get the raw values in case the scales have already been changed.
// Since the measurements are noisy, they should be averaged.
xyz_total[0]-=imu.magADC[0];
xyz_total[1]-=imu.magADC[1];
xyz_total[2]-=imu.magADC[2];
// Detect saturation.
if (-(1<<12) >= min(imu.magADC[0],min(imu.magADC[1],imu.magADC[2]))) {
bret=false;
break; // Breaks out of the for loop. No sense in continuing if we saturated.
}
}
magGain[0]=fabs(820.0*HMC58X3_X_SELF_TEST_GAUSS*2.0*10.0/xyz_total[0]);
magGain[1]=fabs(820.0*HMC58X3_Y_SELF_TEST_GAUSS*2.0*10.0/xyz_total[1]);
magGain[2]=fabs(820.0*HMC58X3_Z_SELF_TEST_GAUSS*2.0*10.0/xyz_total[2]);
// leave test mode
i2c_writeReg(MAG_ADDRESS ,HMC58X3_R_CONFA ,0x70 ); //Configuration Register A -- 0 11 100 00 num samples: 8 ; output rate: 15Hz ; normal measurement mode
i2c_writeReg(MAG_ADDRESS ,HMC58X3_R_CONFB ,0x20 ); //Configuration Register B -- 001 00000 configuration gain 1.3Ga
i2c_writeReg(MAG_ADDRESS ,HMC58X3_R_MODE ,0x00 ); //Mode register -- 000000 00 continuous Conversion Mode
delay(100);
magInit = 1;
if (!bret) { //Something went wrong so get a best guess
magGain[0] = 1.0;
magGain[1] = 1.0;
magGain[2] = 1.0;
}
} // Mag_init().
#endif
That’s how it handles a genuine HMC5883. The QMC5883 is missing some registers or something, so I cant just change a few hex addresses. Here’s the MultiWii code I found that gets me data but it needs scaled and calibrated somehow.
// ************************************************************************************************************
// I2C Compass QMC5883L
// ************************************************************************************************************
// I2C adress: 0x0D (7bit)
// ************************************************************************************************************
#if defined(QMC5883)
#define MAG_ADDRESS 0x0D
#define MAG_DATA_REGISTER 0x00
//REG CONTROL
#define MAG_CTRL_REG1 0x09
#define QMC_MODE 0xC1 // 11 00 00 01OSR=64(11); Range=2G(00); ODR=10Hz(00); MODE=Cont(01)
#define MAG_CTRL_REG2 0x0A
void Mag_init() {
i2c_writeReg(MAG_ADDRESS,0x0B,0x01);
i2c_writeReg(MAG_ADDRESS,MAG_CTRL_REG1,QMC_MODE);
}
static void getADC() {
i2c_getSixRawADC(MAG_ADDRESS,MAG_DATA_REGISTER);
MAG_ORIENTATION( ((rawADC[1]<<8) | rawADC[0]) ,
((rawADC[3]<<8) | rawADC[2]) ,
((rawADC[5]<<8) | rawADC[4]) );
}
#if !defined(MPU6050_I2C_AUX_MASTER)
static void Device_Mag_getADC() {
getADC();
}
#endif
#endif
How do I scale this data as it is collected?
