IMU
Inertial measurement units (IMUs) fuse accelerometers and gyros (sometimes magnetometers) on one chip, used in drones, wearables, and orientation tracking.
Different sensors use different physics: a thermistor changes resistance with temperature; a photodiode produces current under light; a MEMS accelerometer measures the deflection of a tiny silicon spring; an ultrasonic sensor times the round-trip of a click.
In plain terms
Five senses for your microcontroller. Each sensor is one of those senses translated into electricity.
Why designers use it
- Track orientation in drones, robots, and VR controllers.
- Detect free-fall in laptops and disks.
- Stabilize handhelds and gimbals.
Best for
- Environmental monitoring
- Human-machine interfaces
- Industrial control loops
- Health and fitness wearables
Key specifications
- Operating limits: Check the exact manufacturer's datasheet (A family name does not establish voltage, current, temperature or timing limits.)
- Pin assignment: Match the complete part and package code (A similar name or function does not guarantee the same wiring.)
- Mechanical fit: Use the exact package drawing (Check pad layout, dimensions and viewing direction before building.)
When not to use it
- Where a simple switch or threshold would do — sensors add complexity and cost.
- Where firmware can't handle the noise or calibration the sensor demands.
Common mistakes
- Skipping the data-sheet recommended decoupling and seeing noise dominate the measurement.
- Mounting a temperature sensor where the MCU's heat dwarfs the signal.
- Forgetting to calibrate — raw sensor counts ≠ engineering units.
Where you will find it
- A resistive sensing element can be placed in a divider or bridge so its resistance change becomes a measurable voltage.
- A measurement chain may combine a sensor, conditioning electronics and an ADC. Each stage contributes its own limits.
A short history
Inertial Measurement Units (IMUs) combining accelerometers and gyroscopes traditionally used spinning-mass gyros and pendulum accelerometers in aerospace and military systems, costing thousands of dollars. The breakthrough came with MEMS technology: Analog Devices' ADXL50 monolithic accelerometer (announced 1991, volume 1993) and InvenSense's MEMS gyroscopes (the company was founded in 2003). InvenSense's MPU-6050, a 6-axis integrated MEMS IMU released around 2011 at low cost, brought IMU functionality to drones, smartphones, and game controllers. Bosch's BMI series and ST Microelectronics' LSM6 family extend this to automotive-grade IMUs with sub-degree-per-hour gyro bias stability. Modern smartphone IMUs combine 3-axis accelerometer + 3-axis gyro + 3-axis magnetometer in a single 2 × 2 mm package and underpin every navigation, gaming, and image-stabilisation feature.