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Basic/Fire/Gray/M5GO IMU Attitude Sensor MPU9250
The attitude sensor MPU9250 is a multi-chip module that integrates two chips. One chip is the MPU6500, consisting of a 3-axis gyroscope and a 3-axis accelerometer. The other is the AK8963, a 3-axis magnetometer.
Note: Before using, an
MPU9250 IMU object should be created.initMPU9250()
Description:
Initializes the MPU6500 chip.
Syntax:
void initMPU9250();Example:
cpp
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#include <M5Stack.h>#include "utility/MPU9250.h" MPU9250 IMU; // new a MPU9250 object void setup(){ M5.begin(); Serial.begin(115200); IMU.initMPU9250(); byte c = IMU.readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250); Serial.print("MPU9250 "); Serial.print("I AM "); Serial.print(c, HEX);}initAK8963()
Description:
Initializes the AK8963 chip.
Syntax:
void initAK8963(float * destination);| Parameter | Description |
|---|---|
| destination | Pointer to the array of factory preset default values inside the AK8963 chip |
Example:
cpp
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#include <M5Stack.h>#include "utility/MPU9250.h" MPU9250 IMU; // new a MPU9250 object void setup(){ M5.begin(); Serial.begin(115200); // "magCalibration[3] = {0};" was defined at file "MPU9250.h" IMU.initAK8963(IMU.magCalibration); Serial.println("AK8963 initialized for active data mode...."); if (Serial) { // Serial.println("Calibration values: "); Serial.print("X-Axis sensitivity adjustment value "); Serial.println(IMU.magCalibration[0], 2); Serial.print("Y-Axis sensitivity adjustment value "); Serial.println(IMU.magCalibration[1], 2); Serial.print("Z-Axis sensitivity adjustment value "); Serial.println(IMU.magCalibration[2], 2); }}calibrateMPU9250()
Description:
After initializing the chip, this function reads and saves the gyroscope and accelerometer offset values in their respective offset registers when in a stationary state.
Syntax:
void calibrateMPU9250(float * gyroBias, float * accelBias);| Parameter | Description |
|---|---|
| gyroBias | Address of the array to save the gyroscope offset values |
| accelBias | Address of the array to save the accelerometer offset values |
Example:
cpp
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#include <M5Stack.h>#include "utility/MPU9250.h" MPU9250 IMU; // new a MPU9250 object void setup(){ M5.begin(); Serial.begin(115200); IMU.initMPU9250(); byte c = IMU.readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250); Serial.print("MPU9250 "); Serial.print("I AM "); Serial.print(c, HEX); // "gyroBias[3] = {0};" was defined at file "MPU9250.h" // "accelBias[3] = {0};" was defined at file "MPU9250.h" IMU.calibrateMPU9250(IMU.gyroBias, IMU.accelBias); M5.Lcd.fillScreen(BLACK); M5.Lcd.setTextSize(1); M5.Lcd.setCursor(0, 0); M5.Lcd.print("MPU9250 bias"); M5.Lcd.setCursor(0, 16); M5.Lcd.print(" x y z "); M5.Lcd.setCursor(0, 32); M5.Lcd.print((int)(1000*IMU.accelBias[0])); M5.Lcd.setCursor(32, 32); M5.Lcd.print((int)(1000*IMU.accelBias[1])); M5.Lcd.setCursor(64, 32); M5.Lcd.print((int)(1000*IMU.accelBias[2])); M5.Lcd.setCursor(96, 32); M5.Lcd.print("mg"); M5.Lcd.setCursor(0, 48); M5.Lcd.print(IMU.gyroBias[0], 1); M5.Lcd.setCursor(32, 48); M5.Lcd.print(IMU.gyroBias[1], 1); M5.Lcd.setCursor(64, 48); M5.Lcd.print(IMU.gyroBias[2], 1); M5.Lcd.setCursor(96, 48); M5.Lcd.print("o/s");} void loop(){ }readByte()
Description:
Reads and returns the value from a specified register; value length is 8 bits.
Syntax:
uint8_t readByte(uint8_t address, uint8_t subAddress);| Parameter | Description |
|---|---|
| address | Chip address (MPU9250/AK8963) |
| subAddress | Internal register address of the chip |
Example:
cpp
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#include <M5Stack.h>#include "utility/MPU9250.h" MPU9250 IMU; // new a MPU9250 object void setup(){ M5.begin(); Serial.begin(115200); byte c = IMU.readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250); Serial.print("MPU9250 "); Serial.print("I AM "); Serial.print(c, HEX);}readGyroData()
Description:
Reads the gyroscope values in three directions.
Syntax:
void readGyroData(int16_t * destination);| Parameter | Description |
|---|---|
| destination | Address of the array to save the gyroscope values |
Example:
cpp
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#include <M5Stack.h>#include "utility/MPU9250.h" MPU9250 IMU; // new a MPU9250 object void setup(){ M5.begin(); Serial.begin(115200); IMU.initMPU9250(); byte c = IMU.readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250); Serial.print("MPU9250 "); Serial.print("I AM "); Serial.print(c, HEX); IMU.calibrateMPU9250(IMU.gyroBias, IMU.accelBias);} void loop(){ // If intPin goes high, all data registers have new data // On interrupt, check if data ready interrupt if (IMU.readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01) { // "gyroCount[3] = {0};" was defined at file "MPU9250.h" IMU.readGyroData(IMU.gyroCount); // Read the x/y/z adc values IMU.getGres(); // get Gyro scales saved to "gRes" IMU.gx = (float)IMU.gyroCount[0]*IMU.gRes; IMU.gy = (float)IMU.gyroCount[1]*IMU.gRes; IMU.gz = (float)IMU.gyroCount[2]*IMU.gRes; Serial.print("X-gyro rate: "); Serial.print(IMU.gx, 3); Serial.print(" degrees/sec "); Serial.print("Y-gyro rate: "); Serial.print(IMU.gy, 3); Serial.print(" degrees/sec "); Serial.print("Z-gyro rate: "); Serial.print(IMU.gz, 3); Serial.println(" degrees/sec"); }}readAccelData()
Description:
Reads the accelerometer values in three directions.
Syntax:
void readAccelData(int16_t * destination);| Parameter | Description |
|---|---|
| destination | Address of the array to save the accelerometer values |
Example:
cpp
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#include <M5Stack.h>#include "utility/MPU9250.h" MPU9250 IMU; // new a MPU9250 object void setup(){ M5.begin(); Serial.begin(115200); IMU.initMPU9250(); byte c = IMU.readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250); Serial.print("MPU9250 "); Serial.print("I AM "); Serial.print(c, HEX); IMU.calibrateMPU9250(IMU.gyroBias, IMU.accelBias);} void loop(){ // If intPin goes high, all data registers have new data // On interrupt, check if data ready interrupt if (IMU.readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01) { // "accelCount[3] = {0};" was defined at file "MPU9250.h" IMU.readAccelData(IMU.accelCount); IMU.getAres(); // get accelerometer scales saved to "aRes" IMU.ax = (float)IMU.accelCount[0]* IMU.aRes; // - accelBias[0]; IMU.ay = (float)IMU.accelCount[1]*IMU.aRes; // - accelBias[1]; IMU.az = (float)IMU.accelCount[2]*IMU.aRes; // - accelBias[2]; Serial.print("X-acceleration: "); Serial.print(1000*IMU.ax); Serial.print(" mg "); Serial.print("Y-acceleration: "); Serial.print(1000*IMU.ay); Serial.print(" mg "); Serial.print("Z-acceleration: "); Serial.print(1000*IMU.az); Serial.println(" mg "); }}readTempData()
Description:
Reads the temperature.
Syntax:
int16_t readTempData(void);Example:
cpp
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#include <M5Stack.h>#include "utility/MPU9250.h" MPU9250 IMU; // new a MPU9250 object void setup(){ M5.begin(); Wire.begin(); IMU.calibrateMPU9250(IMU.gyroBias, IMU.accelBias); IMU.initMPU9250(); IMU.initAK8963(IMU.magCalibration);} void loop(){ IMU.tempCount = IMU.readTempData(); IMU.temperature = ((float) IMU.tempCount) / 333.87 + 21.0; M5.Lcd.setCursor(0, 0); M5.Lcd.print("MPU9250 Temperature is "); M5.Lcd.print(IMU.temperature, 1); delay(500);}