Accelerometer / Gyro / IMU
Sensor
Accelerometers feel gravity and motion, gyros feel rotation rate; an IMU packages both (often + magnetometer) with an I2C/SPI interface. Sensor fusion turns their noisy, drifting outputs into a usable orientation.
What it looks like
Accelerometer / Gyro / IMU
A typical sensor — exact shape, colour and markings vary between manufacturers.
Types & variants
Key specs
Ranges
g / °/sSelectable, e.g. ±2–16 g and ±250–2000 °/s — range trades against resolution.
Noise density
µg/√HzFloor of what motion you can resolve.
Gyro bias drift
°/hWhy gyro-only heading slowly rotates — fusion corrects it.
Output rate
HzSample rate available over I2C/SPI.
Markings
Tiny LGA chips — identify by the breakout board silkscreen (GY-521 = MPU6050).
Standard values
MPU6050 (classic 6-axis), LSM6DS3, BNO055 (fusion onboard).
How to choose
Hobby orientation: MPU6050 + a complementary/Madgwick filter. Skip the maths: BNO055 outputs fused quaternions directly. Check axis ranges suit the motion (drones need high °/s).
Pinout & package
Breakouts: Vcc (3.3/5 V), GND, SDA, SCL, plus INT. Mount rigidly; vibration is noise.
Example circuits
- Self-balancing robot (angle from complementary filter)
- Quadcopter flight controller
- Step counter / fall detector
Common failures
Reflow-cracked solder on modules (axes go dead), gyro drift misread as failure, I2C address conflicts, and vibration aliasing corrupting everything on drones without damping.
How to test
I2C scan finds it; read WHO_AM_I register for the expected ID. At rest, accel Z ≈ +1 g and gyro ≈ 0 — flip the board and watch axes follow gravity.
Substitutes
Any IMU in the same class with driver support; for pure tilt sensing a cheap accelerometer alone (no gyro) may suffice.