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I’ve written the attach class to get the accelerometer and gyro data from the ICM-20948 unit.
Unfortunately the data fluctuates massively when I am trying to do a basic calibration.
Can anyone help me? Am I getting the reading correctly or is it my calibration that is off.
The unit is by itself flat in another room with not noise or anything there.
My current usage is
var i2cSettings = new I2cConnectionSettings(105,1);
var i2cDevice = I2cDevice.Create(i2cSettings);
_icm20948 = new Icm20948(i2cDevice);
// Set bandwidth for accelerometer and gyroscope
var bandwidth = 50;
_icm20948.SetBandwidth(bandwidth, bandwidth);
For completeness from the pi
sudo i2cdetect -y 1 # for I2C bus 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- 69 -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
Also when getting the data i now get a sample of 10 values
“` GetDataAsync()
public async Task
{
if (_icm20948 == null)
{
throw new InvalidOperationException(“ICM20948 is not initialized.”);
}
int numReadings = 10;
Vector3 accelTotal = new Vector3(0, 0, 0);
Vector3 gyroTotal = new Vector3(0, 0, 0);
for (int i = 0; i < numReadings; i++) { var acceleration = _icm20948.GetAccelerometer(); var angularVelocity = _icm20948.GetGyroscope(); accelTotal += acceleration; gyroTotal += angularVelocity; await Task.Delay(10); // Small delay between readings } Vector3 accelAverage = accelTotal / numReadings; Vector3 gyroAverage = gyroTotal / numReadings; var pitch = CalculatePitch(accelAverage); var roll = CalculateRoll(accelAverage); var currentTime = DateTime.Now; var deltaTime = (currentTime - _lastUpdate).TotalSeconds; _lastUpdate = currentTime; _previousYaw += gyroAverage.Z * deltaTime; var yaw = _previousYaw; _logger.LogInformation($"Data from ICM20948 is Pitch:{pitch}, Roll:{roll}, Yaw:{yaw}."); return new AccelerometerData { Pitch = pitch, Roll = roll, Yaw = yaw }; } ```
where
“`
private double CalculatePitch(Vector3 acceleration) =>
Math.Atan2(acceleration.X, Math.Sqrt(acceleration.Y * acceleration.Y + acceleration.Z * acceleration.Z)) * (180.0 / Math.PI);
private double CalculateRoll(Vector3 acceleration) =>
Math.Atan2(acceleration.Y, Math.Sqrt(acceleration.X * acceleration.X + acceleration.Z * acceleration.Z)) * (180.0 / Math.PI);
private double CalculateYaw(Vector3 angularVelocity, double deltaTime, ref double previousYaw)
{
previousYaw += angularVelocity.Z * deltaTime;
return previousYaw;
}
“`
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