Hi, I'm using Arduino UNO and I2C protocol to read data from MPU 9250. But the sampling rate is lower than the one I selected, indeed, I try to use 1KHz but the maximum speed I can reach is by reading only one of the sensor and is 25 Hz.
//#include <SoftwareSerial.h>
//SoftwareSerial MyBlue(2, 3);
#include "Wire.h"
#include "Timer.h"
#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
Timer t;
#define MPU9250_ADDRESS 0x68 // Device address when ADO = 0
#define AK8963_ADDRESS 0x0C // Address of magnetometer
// class default I2C address is 0x68
// specific I2C addresses may be passed as a parameter here
// AD0 low = 0x68 (default for InvenSense evaluation board)
// AD0 high = 0x69
float timeChange=20;
float dt=timeChange*0.001;
//float angleAx,angleAy, angleAz;//The angle between the accelerometer and x,y,z corrdinate
float ax, ay, az, gx, gy, gz;//Some original data of accelerometer, gyroscope and magenetometer
float mx, my, mz;
float magCalibration[3]={0, 0 ,0};
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
// Specify sensor full scale
uint8_t Gscale = 0; //GFS_250DPS;
uint8_t Ascale = 0; //AFS_2G;
uint8_t Mscale = 1; // 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./32768.0; // *(PI/180.0); degrees/s
float mRes = 1000.*4219./32760.0; // nT
float aRes = 2./32768.0; //g
float lastUpdate=0;
float Now, deltat;
void setup() {
Wire.begin();//Initialize
Serial.begin(115200);//Initialize the serial
//MyBlue.begin(9600);
initMPU9250(); //Inititalize the accelerometer
initAK8963(magCalibration);//Initialize the magnetometer
//int tickEvent1=t.every(timeChange, get_motion);
//int tickEvent2=t.every(500, printout) ;//print out the serial 50 after this line
}
void loop() {
get_motion();
printout();
Now = micros();
deltat = ((Now - lastUpdate)/1000000.0f); // set integration time by time elapsed since last filter update
lastUpdate = Now;
Serial.println(deltat);
}
void printout()
{
Serial.print(ax);
Serial.print(',');
Serial.print(ay);
Serial.print(',');
Serial.println(az);
Serial.print(',');
Serial.print(gx);
Serial.print(',');
Serial.print(gy);
Serial.print(',');
Serial.println(gz);
Serial.print(',');
Serial.print(mx);
Serial.print(',');
Serial.print(my);
Serial.print(',');
Serial.println(mz);
}
void get_motion()
{
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;
ay = (float)accelCount[1] * aRes; //* 9.81;
az = (float)accelCount[2] * aRes; //* 9.81;
readGyroData(gyroCount); // Read the x/y/z adc values
// Calculate the gyro value into actual degrees per second
gx = (float)gyroCount[0] * gRes;
gy = (float)gyroCount[1] * gRes;
gz = (float)gyroCount[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];
my = (float)magCount[1] * mRes * magCalibration[1];
mz = (float)magCount[2] * mRes * magCalibration[2];
}
}
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 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);
}
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, 0x01);
// Set sample rate = gyroscope output rate/(1 + SMPLRT_DIV)
writeByte(MPU9250_ADDRESS, SMPLRT_DIV, 0x00); // 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 | 0x02; // 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
}