Hi! I'm trying to develop an easy auto calibration for the magnetometer. But I don't want to use the 8 calibration because is not user friendly and requires too much time. Do you know some alternatives easier to perform also in the arduino ide???
Welcome to the forum.
The magnetic North is not pointing to the horizon, it is pointing downwards or upwards. That means all three axis are needed. Since the range has to be detected for maximum negative and maximum positive of all three axis, at least 6 measurement points are needed.
There is no easy way.
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Satisfactory calibration requires an offset and scale factor for each axis, so you need determine six independent parameters.
What are your ideas for making this easy?
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I’m sorry I didn’t explain myself well.
I’m trying to find an algorithm that don’t need too much movement in the 3D space like the one that need to move the device in a 8 and at the same time I wanted to be implemented in the ide of arduino not like magneto. I saw there are some type of calibration that are more accurate but they need to compute eigenvalue that are not easy to implement in the arduino ide. Do you have some algorithms already implemented of this type?
I don’t care if required few seconds but I want to reduce the movements required.
In addition my min max algorithm is not accurate for the yaw computation.
#include <Wire.h>
//#include "lib/magnetic.c"
//#include <SoftwareSerial.h>
// See also MPU-9250 Register Map and Descriptions, Revision 4.0, RM-MPU-9250A-00, Rev. 1.4, 9/9/2013 for registers not listed in
// above document; the MPU9250 and MPU9150 are virtually identical but the latter has a different register map
//
//Magnetometer Registers
#define AK8963_ADDRESS 0x0C
#define AK8963_WHO_AM_I 0x00 // should return 0x48
#define AK8963_INFO 0x01
#define AK8963_ST1 0x02 // data ready status bit 0
#define AK8963_XOUT_L 0x03 // data
#define AK8963_XOUT_H 0x04
#define AK8963_YOUT_L 0x05
#define AK8963_YOUT_H 0x06
#define AK8963_ZOUT_L 0x07
#define AK8963_ZOUT_H 0x08
#define AK8963_ST2 0x09 // Data overflow bit 3 and data read error status bit 2
#define AK8963_CNTL 0x0A // Power down (0000), single-measurement (0001), self-test (1000) and Fuse ROM (1111) modes on bits 3:0
#define AK8963_ASTC 0x0C // Self test control
#define AK8963_I2CDIS 0x0F // I2C disable
#define AK8963_ASAX 0x10 // Fuse ROM x-axis sensitivity adjustment value
#define AK8963_ASAY 0x11 // Fuse ROM y-axis sensitivity adjustment value
#define AK8963_ASAZ 0x12 // Fuse ROM z-axis sensitivity adjustment value
#define SELF_TEST_X_GYRO 0x00
#define SELF_TEST_Y_GYRO 0x01
#define SELF_TEST_Z_GYRO 0x02
/*#define X_FINE_GAIN 0x03 // [7:0] fine gain
#define Y_FINE_GAIN 0x04
#define Z_FINE_GAIN 0x05
#define XA_OFFSET_H 0x06 // User-defined trim values for accelerometer
#define XA_OFFSET_L_TC 0x07
#define YA_OFFSET_H 0x08
#define YA_OFFSET_L_TC 0x09
#define ZA_OFFSET_H 0x0A
#define ZA_OFFSET_L_TC 0x0B */
#define SELF_TEST_X_ACCEL 0x0D
#define SELF_TEST_Y_ACCEL 0x0E
#define SELF_TEST_Z_ACCEL 0x0F
#define SELF_TEST_A 0x10
#define XG_OFFSET_H 0x13 // User-defined trim values for gyroscope
#define XG_OFFSET_L 0x14
#define YG_OFFSET_H 0x15
#define YG_OFFSET_L 0x16
#define ZG_OFFSET_H 0x17
#define ZG_OFFSET_L 0x18
#define SMPLRT_DIV 0x19
#define CONFIG 0x1A
#define GYRO_CONFIG 0x1B
#define ACCEL_CONFIG 0x1C
#define ACCEL_CONFIG2 0x1D
#define LP_ACCEL_ODR 0x1E
#define WOM_THR 0x1F
#define MOT_DUR 0x20 // Duration counter threshold for motion interrupt generation, 1 kHz rate, LSB = 1 ms
#define ZMOT_THR 0x21 // Zero-motion detection threshold bits [7:0]
#define ZRMOT_DUR 0x22 // Duration counter threshold for zero motion interrupt generation, 16 Hz rate, LSB = 64 ms
#define FIFO_EN 0x23
#define I2C_MST_CTRL 0x24
#define I2C_SLV0_ADDR 0x25
#define I2C_SLV0_REG 0x26
#define I2C_SLV0_CTRL 0x27
#define I2C_SLV1_ADDR 0x28
#define I2C_SLV1_REG 0x29
#define I2C_SLV1_CTRL 0x2A
#define I2C_SLV2_ADDR 0x2B
#define I2C_SLV2_REG 0x2C
#define I2C_SLV2_CTRL 0x2D
#define I2C_SLV3_ADDR 0x2E
#define I2C_SLV3_REG 0x2F
#define I2C_SLV3_CTRL 0x30
#define I2C_SLV4_ADDR 0x31
#define I2C_SLV4_REG 0x32
#define I2C_SLV4_DO 0x33
#define I2C_SLV4_CTRL 0x34
#define I2C_SLV4_DI 0x35
#define I2C_MST_STATUS 0x36
#define INT_PIN_CFG 0x37
#define INT_ENABLE 0x38
#define DMP_INT_STATUS 0x39 // Check DMP interrupt
#define INT_STATUS 0x3A
#define ACCEL_XOUT_H 0x3B
#define ACCEL_XOUT_L 0x3C
#define ACCEL_YOUT_H 0x3D
#define ACCEL_YOUT_L 0x3E
#define ACCEL_ZOUT_H 0x3F
#define ACCEL_ZOUT_L 0x40
#define TEMP_OUT_H 0x41
#define TEMP_OUT_L 0x42
#define GYRO_XOUT_H 0x43
#define GYRO_XOUT_L 0x44
#define GYRO_YOUT_H 0x45
#define GYRO_YOUT_L 0x46
#define GYRO_ZOUT_H 0x47
#define GYRO_ZOUT_L 0x48
#define EXT_SENS_DATA_00 0x49
#define EXT_SENS_DATA_01 0x4A
#define EXT_SENS_DATA_02 0x4B
#define EXT_SENS_DATA_03 0x4C
#define EXT_SENS_DATA_04 0x4D
#define EXT_SENS_DATA_05 0x4E
#define EXT_SENS_DATA_06 0x4F
#define EXT_SENS_DATA_07 0x50
#define EXT_SENS_DATA_08 0x51
#define EXT_SENS_DATA_09 0x52
#define EXT_SENS_DATA_10 0x53
#define EXT_SENS_DATA_11 0x54
#define EXT_SENS_DATA_12 0x55
#define EXT_SENS_DATA_13 0x56
#define EXT_SENS_DATA_14 0x57
#define EXT_SENS_DATA_15 0x58
#define EXT_SENS_DATA_16 0x59
#define EXT_SENS_DATA_17 0x5A
#define EXT_SENS_DATA_18 0x5B
#define EXT_SENS_DATA_19 0x5C
#define EXT_SENS_DATA_20 0x5D
#define EXT_SENS_DATA_21 0x5E
#define EXT_SENS_DATA_22 0x5F
#define EXT_SENS_DATA_23 0x60
#define MOT_DETECT_STATUS 0x61
#define I2C_SLV0_DO 0x63
#define I2C_SLV1_DO 0x64
#define I2C_SLV2_DO 0x65
#define I2C_SLV3_DO 0x66
#define I2C_MST_DELAY_CTRL 0x67
#define SIGNAL_PATH_RESET 0x68
#define MOT_DETECT_CTRL 0x69
#define USER_CTRL 0x6A // Bit 7 enable DMP, bit 3 reset DMP
#define PWR_MGMT_1 0x6B // Device defaults to the SLEEP mode
#define PWR_MGMT_2 0x6C
#define DMP_BANK 0x6D // Activates a specific bank in the DMP
#define DMP_RW_PNT 0x6E // Set read/write pointer to a specific start address in specified DMP bank
#define DMP_REG 0x6F // Register in DMP from which to read or to which to write
#define DMP_REG_1 0x70
#define DMP_REG_2 0x71
#define FIFO_COUNTH 0x72
#define FIFO_COUNTL 0x73
#define FIFO_R_W 0x74
#define WHO_AM_I_MPU9250 0x75 // Should return 0x71
#define XA_OFFSET_H 0x77
#define XA_OFFSET_L 0x78
#define YA_OFFSET_H 0x7A
#define YA_OFFSET_L 0x7B
#define ZA_OFFSET_H 0x7D
#define ZA_OFFSET_L 0x7E
// Using the MSENSR-9250 breakout board, ADO is set to 0
// Seven-bit device address is 110100 for ADO = 0 and 110101 for ADO = 1
#define MPU9250_ADDRESS 0x68 // Device address when ADO = 0
#define AK8963_ADDRESS 0x0C // Address of magnetometer
#define AHRS true // set to false for basic data read
#define SerialDebug true // set to true to get Serial output for debugging
#define CALIBRATION
// Set initial input parameters
enum Ascale {
AFS_2G = 0,
AFS_4G,
AFS_8G,
AFS_16G
};
enum Gscale {
GFS_250DPS = 0,
GFS_500DPS,
GFS_1000DPS,
GFS_2000DPS
};
enum Mscale {
MFS_14BITS = 0, // 0.6 mG per LSB
MFS_16BITS // 0.15 mG per LSB
};
// Specify sensor full scale
uint8_t Gscale = 0; //GFS_250DPS;
uint8_t Ascale = 0; //AFS_2G;
uint8_t Mscale = MFS_16BITS; // Choose either 14-bit or 16-bit magnetometer resolution
uint8_t Mmode = 0x02; // 2 for 8 Hz, 6 for 100 Hz continuous magnetometer data read
// scale resolutions per LSB for the sensors
float gRes = 250./32767.5*(PI/180.0);
float mRes = 10.*4219./32760.0;
float aRes = 2./32767.5f;
// Pin definitions
int16_t accelCount[3]; // Stores the 16-bit signed accelerometer sensor output
int16_t gyroCount[3]; // Stores the 16-bit signed gyro sensor output
int16_t magCount[3]; // Stores the 16-bit signed magnetometer sensor output
float magCalibration[3] = {0, 0, 0};
float magbias[6] = {0, 0, 0, 0, 0, 0}; // Factory mag calibration and mag bias
float gyroBias[3] = { -310.4, 135.7, 278.0};
float accelBias[6] = {515.0, 279.0, 1500.0, 5.96e-5, 6.26e-5, 6.06e-5}; // Bias corrections for gyro and accelerometer
// global constants for 9 DoF fusion and AHRS (Attitude and Heading Reference System)
float GyroMeasError = PI * (40.0f / 180.0f); // gyroscope measurement error in rads/s (start at 40 deg/s)
float GyroMeasDrift = PI * (0.0f / 180.0f); // gyroscope measurement drift in rad/s/s (start at 0.0 deg/s/s)
// There is a tradeoff in the beta parameter between accuracy and response speed.
// In the original Madgwick study, beta of 0.041 (corresponding to GyroMeasError of 2.7 degrees/s) was found to give optimal accuracy.
// However, with this value, the LSM9SD0 response time is about 10 seconds to a stable initial quaternion.
// Subsequent changes also require a longish lag time to a stable output, not fast enough for a quadcopter or robot car!
// By increasing beta (GyroMeasError) by about a factor of fifteen, the response time constant is reduced to ~2 sec
// I haven't noticed any reduction in solution accuracy. This is essentially the I coefficient in a PID control sense;
// the bigger the feedback coefficient, the faster the solution converges, usually at the expense of accuracy.
// In any case, this is the free parameter in the Madgwick filtering and fusion scheme.
float beta = sqrt(3.0f / 4.0f) * GyroMeasError; // compute beta
float zeta = sqrt(3.0f / 4.0f) * GyroMeasDrift; // compute zeta, the other free parameter in the Madgwick scheme usually set to a small or zero value
#define Kp 2.0f * 5.0f // these are the free parameters in the Mahony filter and fusion scheme, Kp for proportional feedback, Ki for integral
#define Ki 0.0f
uint32_t delt_t = 0; // used to control display output rate
uint32_t count = 0, sumCount = 0; // used to control display output rate
float pitch = 0;
float yaw = 0;
float roll = 0;
float deltat = 0.0f, sum = 0.0f; // integration interval for both filter schemes
uint32_t lastUpdate = 0, firstUpdate = 0; // used to calculate integration interval
uint32_t Now = 0; // used to calculate integration interval
float ax, ay, az, gx, gy, gz, mx, my, mz; // variables to hold latest sensor data values
float q[4] = {1.0f, 0.0f, 0.0f, 0.0f}; // vector to hold quaternion
float eInt[3] = {0.0f, 0.0f, 0.0f}; // vector to hold integral error for Mahony method
float offset=0;
int a = 0, x = 1;
float acc_cal[3] = {0, 0, 0};
int16_t calaX, calaY, calaZ;
float gyro_cal[3] = {0, 0, 0};
int16_t calgX, calgY, calgZ;
float r11, r12, r13, r21, r22, r23, r31, r32, r33;
float aX = 0;
float aY = 0;
float aZ = 0;
float vX, vY, vZ;
float X, Y, Z;
float aX_1, aY_1, aZ_1;
float yaw_1, pitch_1, roll_1;
float accX[4]={0, 0, 0, 0}, accY[4]={0, 0, 0, 0}, accZ[4]={0, 0, 0, 0};
float velX[4]={0, 0, 0, 0}, velY[4]={0, 0, 0, 0}, velZ[4]={0, 0, 0, 0};
long timer;
int i1 = 0, i2 = 0;
String sensorData = "";
void setup()
{
Wire.begin();
// TWBR = 12; // 400 kbit/sec I2C speed
Serial.begin(9600);
// Read the WHO_AM_I register, this is a good test of communication
byte c = readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250); // Read WHO_AM_I register for MPU-9250
Serial.print("MPU9250 "); Serial.print("I AM "); Serial.print(c, HEX); Serial.print(" I should be "); Serial.println(0x71, HEX);
delay(500);
if (c == 0x71) // WHO_AM_I should always be 0x68
{
//Serial.println("MPU9250 is online...");
delay(500);
initMPU9250();
Serial.println("MPU9250 initialized for active data mode...."); // Initialize device for active mode read of acclerometer, gyroscope, and temperature
// Read the WHO_AM_I register of the magnetometer, this is a good test of communication
byte d = readByte(AK8963_ADDRESS, AK8963_WHO_AM_I); // Read WHO_AM_I register for AK8963
//Serial.print("AK8963 "); Serial.print("I AM "); Serial.print(d, HEX); Serial.print(" I should be "); Serial.println(0x48, HEX);
delay(500);
// Get magnetometer calibration from AK8963 ROM
initAK8963(magCalibration); // Serial.println("AK8963 initialized for active data mode...."); // Initialize device for active mode read of magnetometer
int8_t rawData[6];
for (int i=0; i<1000; i++)
{
readBytes(MPU9250_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array
calaX = ((int16_t)rawData[0] << 8) | rawData[1] ; // Turn the MSB and LSB into a signed 16-bit value
calaY = ((int16_t)rawData[2] << 8) | rawData[3] ;
calaZ = ((int16_t)rawData[4] << 8) | rawData[5] ;
acc_cal[0] += calaX;
acc_cal[1] += calaY;
acc_cal[2] += calaZ;
readBytes(MPU9250_ADDRESS,GYRO_XOUT_H , 6, &rawData[0]); // Read the six raw data registers into data array
calgX = ((int16_t)rawData[0] << 8) | rawData[1] ; // Turn the MSB and LSB into a signed 16-bit value
calgY = ((int16_t)rawData[2] << 8) | rawData[3] ;
calgZ = ((int16_t)rawData[4] << 8) | rawData[5] ;
gyro_cal[0] += calgX;
gyro_cal[1] += calgY;
gyro_cal[2] += calgZ;
}
accelBias[0] = (acc_cal[0] / 1000) * aRes * 9.81;
accelBias[1] = (acc_cal[1] / 1000) * aRes * 9.81;
accelBias[2] = (acc_cal[2] / 1000 )* aRes * 9.81 - 9.81;
gyroBias[0] = gyro_cal[0] / 1000;
gyroBias[1] = gyro_cal[1] / 1000;
gyroBias[2] = gyro_cal[2] / 1000;
///*
Serial.print("Calibration data ");
Serial.print(acc_cal[0] / 1000);
Serial.print(", ");
Serial.print(acc_cal[1]/ 1000);
Serial.print(", ");
Serial.println(acc_cal[2]/1000);
Serial.print(gyro_cal[0] / 1000);
Serial.print(", ");
Serial.print(gyro_cal[1] / 1000);
Serial.print(", ");
Serial.println(gyro_cal[2] / 1000);
//*/
#ifdef CALIBRATION
magcalMPU9250(magbias);
Serial.print(magbias[0] );
Serial.print(", ");
Serial.print(magbias[1] );
Serial.print(", ");
Serial.println(magbias[2] );
Serial.print(magbias[3] );
Serial.print(", ");
Serial.print(magbias[4] );
Serial.print(", ");
Serial.println(magbias[5] );
Serial.print(magCalibration[0] );
Serial.print(", ");
Serial.print(magCalibration[1] );
Serial.print(", ");
Serial.println(magCalibration[2] );
#endif
#ifndef CALIBRATION
accelBias[0] = -431;
accelBias[1] = -8;
accelBias[2] = 10943;
gyroBias[0] = 496;
gyroBias[1] = 836;
gyroBias[2] = 89;
magbias[0] = -36.22;
magbias[1] = 37.79;
magbias[2] = 69.19;
magbias[3] = 2.04;
magbias[4] = 1.53;
magbias[5] = 0.54;
magCalibration[0] = 1.22;
magCalibration[1] = 1.22;
magCalibration[2] = 1.17;
#endif
}
else
{
Serial.print("Could not connect to MPU9250: 0x");
//Serial.println(c, HEX);
while(1) ; // Loop forever if communication doesn't happen
}
}
void loop()
{
// If intPin goes high, all data registers have new data
if (readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01) { // On interrupt, check if data ready interrupt
readAccelData(accelCount); // Read the x/y/z adc values
// Now we'll calculate the accleration value into actual g's
ax = ((float)accelCount[0] * aRes * 9.81 - accelBias[0]); // * accelBias[3]; // get actual g value, this depends on scale being set
ay = ((float)accelCount[1] * aRes * 9.81 - accelBias[1]); // * accelBias[4];
az = ((float)accelCount[2] * aRes * 9.81 - accelBias[2]); // * accelBias[5];
readGyroData(gyroCount); // Read the x/y/z adc values
// Calculate the gyro value into actual degrees per second
gx = ((float)gyroCount[0] - gyroBias[0]) * gRes; // get actual gyro value, this depends on scale being set
gy = ((float)gyroCount[1] - gyroBias[1]) * gRes;
gz = ((float)gyroCount[2] - gyroBias[2]) * gRes;
readMagData(magCount); // Read the x/y/z adc values
// Calculate the magnetometer values in milliGauss
// Include factory calibration per data sheet and user environmental corrections
mx = ((float)magCount[0] * mRes * magCalibration[0] - magbias[0])*magbias[3]; // get actual magnetometer value, this depends on scale being set
my = ((float)magCount[1] * mRes * magCalibration[1] - magbias[1])*magbias[4];
mz = ((float)magCount[2] * mRes * magCalibration[2] - magbias[2])*magbias[5];
}
Now = micros();
deltat = ((Now - lastUpdate)/1000000.0f); // set integration time by time elapsed since last filter update
lastUpdate = Now;
sum += deltat; // sum for averaging filter update rate
sumCount++;
// Sensors x (y)-axis of the accelerometer is aligned with the y (x)-axis of the magnetometer;
// the magnetometer z-axis (+ down) is opposite to z-axis (+ up) of accelerometer and gyro!
// We have to make some allowance for this orientationmismatch in feeding the output to the quaternion filter.
// For the MPU-9250, we have chosen a magnetic rotation that keeps the sensor forward along the x-axis just like
// in the LSM9DS0 sensor. This rotation can be modified to allow any convenient orientation convention.
// This is ok by aircraft orientation standards!
// Pass gyro rate as rad/s
MadgwickQuaternionUpdate(ax, ay, az, gx*PI/180.0f, gy*PI/180.0f, gz*PI/180.0f, my, mx, - mz);
//MahonyQuaternionUpdate(ax, ay, az, gx*PI/180.0f, gy*PI/180.0f, gz*PI/180.0f, my, mx, -mz);
float qw = q[0], qx = q[1], qy = q[2], qz = q[3];
roll_1 = roll;
pitch_1 = pitch;
yaw_1 = yaw;
aX_1 = aX;
aY_1 = aY;
aZ_1 = aZ;
// Define output variables from updated quaternion---these are Tait-Bryan angles, commonly used in aircraft orientation.
// In this coordinate system, the positive z-axis is down toward Earth.
// Yaw is the angle between Sensor x-axis and Earth magnetic North (or true North if corrected for local declination, looking down on the sensor positive yaw is counterclockwise.
// Pitch is angle between sensor x-axis and Earth ground plane, toward the Earth is positive, up toward the sky is negative.
// Roll is angle between sensor y-axis and Earth ground plane, y-axis up is positive roll.
// These arise from the definition of the homogeneous rotation matrix constructed from quaternions.
// Tait-Bryan angles as well as Euler angles are non-commutative; that is, the get the correct orientation the rotations must be
// applied in the correct order which for this configuration is yaw, pitch, and then roll.
// For more see http://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles which has additional links.
roll = atan2(2.0 * (qw * qx + qy * qz), 1.0 - 2.0 * (qx * qx + qy * qy));
pitch = asin(2.0 * (qw * qy - qx * qz));
yaw = atan2(2.0 * (qx * qy + qw * qz), 1.0 - 2.0 * ( qy * qy + qz * qz));
pitch *= 180.0f / PI;
yaw *= 180.0f / PI;
roll *= 180.0f / PI;
yaw = (-yaw + 1.56 );
a++;
//if (a == 150){
// offset=aZ;
//}
Serial.print("Yaw, Pitch, Roll: ");
Serial.print(yaw, 2);
Serial.print(", ");
Serial.print(pitch, 2);
Serial.print(", ");
Serial.println(roll, 2);
r11 = 2.0f * (qw * qw + qx * qx) - 1;
r12 = 2.0f * (qx * qy - qw * qz);
r13 = 2.0f * (qx * qz + qw * qy);
r21 = 2.0f * (qx * qy + qw * qz);
r22 = 2.0f * (qw * qw + qy * qy) - 1;
r23 = 2.0f * (qy * qz - qw * qx);
r31 = 2.0f * (qx * qz - qw * qy);
r32 = 2.0f * (qy * qz + qx * qw);
r33 = 2.0f * (qw * qw + qz * qz) - 1;
// compute acceleration
aX = (r11 * ax + r21 * ay + r31 * az);
aY = (r12 * ax + r22 * ay + r32 * az);
aZ = (r13 * ax + r23 * ay + r33 * az) - offset;
processing(aX, aY, aZ);
if( (a % 2) == 0 )
{
/*
aX = (aX + aX_1)/2;
aY = (aY + aY_1)/2;
aZ = (aZ + aZ_1)/2;
roll = (roll + roll_1)/2;
pitch = (pitch + pitch_1)/2;
yaw = (yaw + yaw_1)/2;
Serial.print((float)(aX));
Serial.print(", ");
Serial.print((float)(aY));
Serial.print(", ");
Serial.println((float)(aZ));
Serial.print((int)(vX));
Serial.print(", ");
Serial.print((int)(vY));
Serial.print(", ");
Serial.print((int)(vZ));
Serial.println(" m/s");
Serial.print((int)(X));
Serial.print(", ");
Serial.print((int)(Y));
Serial.print(", ");
Serial.print((int)(Z));
Serial.print(", ");
Serial.println(" m");
*/
sensorData = "";
sensorData = sensorData + yaw +";";
sensorData = sensorData + pitch +";";
sensorData = sensorData + roll +";";
Serial.println(sensorData);
}
count = millis();
sumCount = 0;
sum = 0;
//delay(50);
}
//===================================================================================================================
//====== Set of useful function to access acceleration. gyroscope, magnetometer, and temperature data
//===================================================================================================================
void readAccelData(int16_t * destination)
{
uint8_t rawData[6]; // x/y/z accel register data stored here
readBytes(MPU9250_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array
destination[0] = ((int16_t)rawData[0] << 8) | rawData[1] ; // Turn the MSB and LSB into a signed 16-bit value
destination[1] = ((int16_t)rawData[2] << 8) | rawData[3] ;
destination[2] = ((int16_t)rawData[4] << 8) | rawData[5] ;
}
void readGyroData(int16_t * destination)
{
uint8_t rawData[6]; // x/y/z gyro register data stored here
readBytes(MPU9250_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array
destination[0] = ((int16_t)rawData[0] << 8) | rawData[1] ; // Turn the MSB and LSB into a signed 16-bit value
destination[1] = ((int16_t)rawData[2] << 8) | rawData[3] ;
destination[2] = ((int16_t)rawData[4] << 8) | rawData[5] ;
}
void readMagData(int16_t * destination)
{
uint8_t rawData[7]; // x/y/z gyro register data, ST2 register stored here, must read ST2 at end of data acquisition
//read mag
writeByte(MPU9250_ADDRESS, INT_PIN_CFG, 0x02); //set i2c bypass enable pin to true to access magnetometer
delay(10);
writeByte(AK8963_ADDRESS, 0x0A, 0x01); //enable the magnetometer
delay(100);
if(readByte(AK8963_ADDRESS, AK8963_ST1) & 0x01) { // wait for magnetometer data ready bit to be set
readBytes(AK8963_ADDRESS, AK8963_XOUT_L, 6, &rawData[0]); // Read the six raw data and ST2 registers sequentially into data array
uint8_t c = rawData[6]; // End data read by reading ST2 register
//if(!(c & 0x08)) { // Check if magnetic sensor overflow set, if not then report data
destination[0] = ((int16_t)rawData[1] << 8) | rawData[0] ; // Turn the MSB and LSB into a signed 16-bit value
destination[1] = ((int16_t)rawData[3] << 8) | rawData[2] ; // Data stored as little Endian
destination[2] = ((int16_t)rawData[5] << 8) | rawData[4] ;
//}
}
}
void processing(float aX,float aY, float aZ)
{
double dt = (double)(millis() - timer) / 1000;
timer = millis();
//compute velocity
if (abs(aX) <= 0.5)
aX=0;
if (abs(aY) <= 0.5)
aY=0;
if (abs(aZ) <= 0.5)
aZ=0;
accX[i1] = aX;
accY[i1] = aY;
accZ[i1] = aZ;
i1++;
if (i1 >= 4) {
i1 = 0;
}
//Serial.print("time: ");
//Serial.println(dt);
vX = vX + (aX * dt);
vY = vY + (aY * dt);
vZ = vZ + (aZ * dt);
if (accX[0] == 0 && accX[1] == 0 && accX[2] == 0 && accX[3] == 0) {
vX = 0;
}
if (accY[0] == 0 && accY[1] == 0 && accY[2] == 0 && accY[3] == 0) {
vY = 0;
}
if (accZ[0] == 0 && accZ[1] == 0 && accZ[2] == 0 && accZ[3] == 0) {
vZ = 0;
}
// compute position
X = X + (vX*dt) + (0.5*aX*dt*dt);
Y = Y + (vY*dt) + (0.5*aY*dt*dt);
Z = Z + (vZ*dt) + (0.5*aZ*dt*dt);
//if (index<100)
// index++;
velX[i2] = vX;
velY[i2] = vY;
velZ[i2] = vZ;
if (i2 >= 4)
i2 = 0;
if (velY[0] == 0 && velY[1] == 0 && velY[2] == 0 && velY[3] == 0) {
Y = 0;
}
if (velX[0] == 0 && velX[1] == 0 && velX[2] == 0 && velX[3] == 0) {
X = 0;
}
if (velZ[0] == 0 && velZ[1] == 0 && velZ[2] == 0 && velZ[3] == 0) {
Z = 0;
}
}
void initAK8963(float * destination)
{
// First extract the factory calibration for each magnetometer axis
uint8_t rawData[3]; // x/y/z gyro calibration data stored here
writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x00); // Power down magnetometer
delay(10);
writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x0F); // Enter Fuse ROM access mode
delay(10);
readBytes(AK8963_ADDRESS, AK8963_ASAX, 3, &rawData[0]); // Read the x-, y-, and z-axis calibration values
destination[0] = (float)(rawData[0] - 128)/256. + 1.; // Return x-axis sensitivity adjustment values, etc.
destination[1] = (float)(rawData[1] - 128)/256. + 1.;
destination[2] = (float)(rawData[2] - 128)/256. + 1.;
writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x00); // Power down magnetometer
delay(10);
// Configure the magnetometer for continuous read and highest resolution
// set Mscale bit 4 to 1 (0) to enable 16 (14) bit resolution in CNTL register,
// and enable continuous mode data acquisition Mmode (bits [3:0]), 0010 for 8 Hz and 0110 for 100 Hz sample rates
writeByte(AK8963_ADDRESS, AK8963_CNTL, Mscale << 4 | Mmode); // Set magnetometer data resolution and sample ODR
delay(10);
}
//mag calibration
void magcalMPU9250(float * dest1)
{
uint16_t ii = 0, sample_count = 0;
int32_t mag_bias[3] = {0, 0, 0}, mag_scale[3] = {0, 0, 0};
int16_t mag_max[10] = {-32767, -32767, -32767, -32767, -32767, -32767, -32767, -32767, -32767, -32767};
int16_t mag_min[10] = {32767, 32767, 32767, 32767, 32767, 32767, 32767, 32767, 32767, 32767}, mag_temp[10] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
Serial.println("Mag Calibration: Wave device in a figure eight until done!");
delay(1000);
// shoot for ~fifteen seconds of mag data
if(Mmode == 0x02) sample_count = 80; // at 8 Hz ODR, new mag data is available every 125 ms
if(Mmode == 0x06) sample_count = 1000; // at 100 Hz ODR, new mag data is available every 10 ms
for(ii = 0; ii < sample_count; ii++) {
readMagData(mag_temp); // Read the mag data
for (int jj = 0; jj < 10; jj++) {
if(mag_temp[jj] > mag_max[jj]) mag_max[jj] = mag_temp[jj];
if(mag_temp[jj] < mag_min[jj]) mag_min[jj] = mag_temp[jj];
}
if(Mmode == 0x02) delay(135); // at 8 Hz ODR, new mag data is available every 125 ms
if(Mmode == 0x06) delay(12); // at 100 Hz ODR, new mag data is available every 10 ms
}
// Get hard iron correction
mag_bias[0] = (mag_max[0] + mag_min[0])/2; // get average x mag bias in counts
mag_bias[1] = (mag_max[1] + mag_min[1])/2; // get average y mag bias in counts
mag_bias[2] = (mag_max[2] + mag_min[2])/2; // get average z mag bias in counts
dest1[0] = (float) mag_bias[0]*mRes*magCalibration[0]; // save mag biases in G for main program
dest1[1] = (float) mag_bias[1]*mRes*magCalibration[1];
dest1[2] = (float) mag_bias[2]*mRes*magCalibration[2];
// Get soft iron correction estimate
mag_scale[0] = (mag_max[0] - mag_min[0])/2; // get average x axis max chord length in counts
mag_scale[1] = (mag_max[1] - mag_min[1])/2; // get average y axis max chord length in counts
mag_scale[2] = (mag_max[2] - mag_min[2])/2; // get average z axis max chord length in counts
float avg_rad = mag_scale[0] + mag_scale[1] + mag_scale[2];
avg_rad /= 3.0;
dest1[3] = avg_rad/((float)mag_scale[0]);
dest1[4] = avg_rad/((float)mag_scale[1]);
dest1[5] = avg_rad/((float)mag_scale[2]);
Serial.println("Mag Calibration done!");
delay(100);
}
void initMPU9250()
{
// wake up device
writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x80);
delay(100);
writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x00); // Clear sleep mode bit (6), enable all sensors
delay(100); // Wait for all registers to reset
// get stable time source
writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x01); // Auto select clock source to be PLL gyroscope reference if ready else
delay(200);
// Configure Gyro and Thermometer
// Disable FSYNC and set thermometer and gyro bandwidth to 41 and 42 Hz, respectively;
// minimum delay time for this setting is 5.9 ms, which means sensor fusion update rates cannot
// be higher than 1 / 0.0059 = 170 Hz
// DLPF_CFG = bits 2:0 = 011; this limits the sample rate to 1000 Hz for both
// With the MPU9250, it is possible to get gyro sample rates of 32 kHz (!), 8 kHz, or 1 kHz
writeByte(MPU9250_ADDRESS, CONFIG, 0x03);
// Set sample rate = gyroscope output rate/(1 + SMPLRT_DIV)
writeByte(MPU9250_ADDRESS, SMPLRT_DIV, 0x04); // Use a 200 Hz rate; a rate consistent with the filter update rate
// determined inset in CONFIG above
// Set gyroscope full scale range
// Range selects FS_SEL and GFS_SEL are 0 - 3, so 2-bit values are left-shifted into positions 4:3
uint8_t c = readByte(MPU9250_ADDRESS, GYRO_CONFIG); // get current GYRO_CONFIG register value
// c = c & ~0xE0; // Clear self-test bits [7:5]
c = c & ~0x03; // Clear Fchoice bits [1:0]
c = c & ~0x18; // Clear GFS bits [4:3]
c = c | Gscale << 3; // Set full scale range for the gyro
// c =| 0x00; // Set Fchoice for the gyro to 11 by writing its inverse to bits 1:0 of GYRO_CONFIG
writeByte(MPU9250_ADDRESS, GYRO_CONFIG, c ); // Write new GYRO_CONFIG value to register
// Set accelerometer full-scale range configuration
c = readByte(MPU9250_ADDRESS, ACCEL_CONFIG); // get current ACCEL_CONFIG register value
// c = c & ~0xE0; // Clear self-test bits [7:5]
c = c & ~0x18; // Clear AFS bits [4:3]
c = c | Ascale << 3; // Set full scale range for the accelerometer
writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, c); // Write new ACCEL_CONFIG register value
// Set accelerometer sample rate configuration
// It is possible to get a 4 kHz sample rate from the accelerometer by choosing 1 for
// accel_fchoice_b bit [3]; in this case the bandwidth is 1.13 kHz
c = readByte(MPU9250_ADDRESS, ACCEL_CONFIG2); // get current ACCEL_CONFIG2 register value
c = c & ~0x0F; // Clear accel_fchoice_b (bit 3) and A_DLPFG (bits [2:0])
c = c | 0x0B; // Set accelerometer rate to 1 kHz and bandwidth to 41 Hz
writeByte(MPU9250_ADDRESS, ACCEL_CONFIG2, c); // Write new ACCEL_CONFIG2 register value
// The accelerometer, gyro, and thermometer are set to 1 kHz sample rates,
// but all these rates are further reduced by a factor of 5 to 200 Hz because of the SMPLRT_DIV setting
// Configure Interrupts and Bypass Enable
// Set interrupt pin active high, push-pull, hold interrupt pin level HIGH until interrupt cleared,
// clear on read of INT_STATUS, and enable I2C_BYPASS_EN so additional chips
// can join the I2C bus and all can be controlled by the Arduino as master
writeByte(MPU9250_ADDRESS, INT_PIN_CFG, 0x22);
writeByte(MPU9250_ADDRESS, INT_ENABLE, 0x01); // Enable data ready (bit 0) interrupt
delay(100);
}
// Wire.h read and write protocols
void writeByte(uint8_t address, uint8_t subAddress, uint8_t data)
{
Wire.beginTransmission(address); // Initialize the Tx buffer
Wire.write(subAddress); // Put slave register address in Tx buffer
Wire.write(data); // Put data in Tx buffer
Wire.endTransmission(); // Send the Tx buffer
}
uint8_t readByte(uint8_t address, uint8_t subAddress)
{
uint8_t data; // `data` will store the register data
Wire.beginTransmission(address); // Initialize the Tx buffer
Wire.write(subAddress); // Put slave register address in Tx buffer
Wire.endTransmission(false); // Send the Tx buffer, but send a restart to keep connection alive
Wire.requestFrom(address, (uint8_t) 1); // Read one byte from slave register address
data = Wire.read(); // Fill Rx buffer with result
return data; // Return data read from slave register
}
void readBytes(uint8_t address, uint8_t subAddress, uint8_t count, uint8_t * dest)
{
Wire.beginTransmission(address); // Initialize the Tx buffer
Wire.write(subAddress); // Put slave register address in Tx buffer
Wire.endTransmission(false); // Send the Tx buffer, but send a restart to keep connection alive
uint8_t i = 0;
Wire.requestFrom(address, count); // Read bytes from slave register address
while (Wire.available()) {
dest[i++] = Wire.read(); } // Put read results in the Rx buffer
}
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