mpu9250

In this article we look the MPU-9250 Nine-Axis (Gyro + Accelerometer + Compass) MEMS MotionTracking™ Device which is fitted to the BPI:bit

The sensor uses the following GPIO

MPU9250_SCL	GPIO 22	Digital Output
MPU9250_SDA	GPIO 21	Digital Output
MPU9250_INT	GPIO 16	Digital Input

 

Parts Required

Name	Link
Banana PI Bit board	Banana PI Bit board with EPS32

 

$19.50 for this board is a good price

Features

Lets look at the sensor features from the manufacturer

Code

You can roll your own code but I chose a library in the Arduino library manager called the MPU9250_asukiaaa

This is one of the default code examples

[codesyntax lang=”cpp”]

#include <MPU9250_asukiaaa.h>

#ifdef _ESP32_HAL_I2C_H_
#define SDA_PIN 21
#define SCL_PIN 22
#endif

MPU9250_asukiaaa mySensor;
float aX, aY, aZ, aSqrt, gX, gY, gZ, mDirection, mX, mY, mZ;

void setup() {
  Serial.begin(115200);
  while(!Serial);
  Serial.println("started");

#ifdef _ESP32_HAL_I2C_H_ // For ESP32
  Wire.begin(SDA_PIN, SCL_PIN);
  mySensor.setWire(&Wire);
#endif

  mySensor.beginAccel();
  mySensor.beginGyro();
  mySensor.beginMag();

  // You can set your own offset for mag values
  // mySensor.magXOffset = -50;
  // mySensor.magYOffset = -55;
  // mySensor.magZOffset = -10;
}

void loop() {
  uint8_t sensorId;
  if (mySensor.readId(&sensorId) == 0) {
    Serial.println("sensorId: " + String(sensorId));
  } else {
    Serial.println("Cannot read sensorId");
  }

  if (mySensor.accelUpdate() == 0) {
    aX = mySensor.accelX();
    aY = mySensor.accelY();
    aZ = mySensor.accelZ();
    aSqrt = mySensor.accelSqrt();
    Serial.println("accelX: " + String(aX));
    Serial.println("accelY: " + String(aY));
    Serial.println("accelZ: " + String(aZ));
    Serial.println("accelSqrt: " + String(aSqrt));
  } else {
    Serial.println("Cannod read accel values");
  }

  if (mySensor.gyroUpdate() == 0) {
    gX = mySensor.gyroX();
    gY = mySensor.gyroY();
    gZ = mySensor.gyroZ();
    Serial.println("gyroX: " + String(gX));
    Serial.println("gyroY: " + String(gY));
    Serial.println("gyroZ: " + String(gZ));
  } else {
    Serial.println("Cannot read gyro values");
  }

  if (mySensor.magUpdate() == 0) {
    mX = mySensor.magX();
    mY = mySensor.magY();
    mZ = mySensor.magZ();
    mDirection = mySensor.magHorizDirection();
    Serial.println("magX: " + String(mX));
    Serial.println("maxY: " + String(mY));
    Serial.println("magZ: " + String(mZ));
    Serial.println("horizontal direction: " + String(mDirection));
  } else {
    Serial.println("Cannot read mag values");
  }

  Serial.println("at " + String(millis()) + "ms");
  Serial.println(""); // Add an empty line
  delay(500);
}

[/codesyntax]

Output

Here is an example of my output

sensorId: 113
accelX: -0.06
accelY: -0.08
accelZ: 1.04
accelSqrt: 1.04
gyroX: 0.67
gyroY: -0.49
gyroZ: -0.55
magX: 95.13
maxY: 8.12
magZ: -105.38
horizontal direction: 85.12
at 102570ms

Links

https://www.invensense.com/products/motion-tracking/9-axis/mpu-9250/

https://www.invensense.com/download-pdf/mpu-9250-datasheet/