If you don't have a electronic compass on board you will need an IMU.
An Inertial Measurement Unit, or IMU, measures and reports on velocity, orientation and gravitational forces, using a combination of an accelerometer, gyroscope, and a magnetometer.
Connecting an IMU to OpenPlotter will provide magnetic heading which is needed to calculate true heading and true wind. You will have heel angle data as well.
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Supported IMU sensors
- InvenSense MPU-9150 single chip IMU.
- InvenSense MPU-6050 plus HMC5883 magnetometer on MPU-6050's aux bus (handled by the MPU-9150 driver).
- InvenSense MPU-6050 gyros + acclerometers. Treated as MPU-9150 without magnetometers.
- InvenSense MPU-9255 single chip IMU (I2C and SPI).
- STM LSM9DS0 single chip IMU.
- STM LSM9DS1 single chip IMU.
- L3GD20H + LSM303D (optionally with the LPS25H) as used on the Pololu AltIMU-10 v4.
- L3GD20 + LSM303DLHC as used on the Adafruit 9-dof (older version with GD20 gyro) IMU.
- L3GD20H + LSM303DLHC (optionally with BMP180) as used on the new Adafruit 10-dof IMU.
- Bosch BMX055 (although magnetometer support is experimental currently).
- Bosch BNO055 IMU with onchip fusion. Note: will not work reliably with RaspberryPi/Pi2 due to clock-stretching issues.
IMU sensors have to be connected by I2C interface. See chapter Wiring I2C sensors.
See Compass chapter to configure IMU sensors.