Sensors · Absolute rotary encoder

AS5600 magnetic encoder

A 12-bit absolute magnetic encoder on a 3 mm chip, for the price of a coffee. Stick a diametric magnet on the shaft and you have joint feedback.

$3 indicative ams OSRAM Absolute rotary encoder

The role it plays

Sensors split into proprioception — encoders, IMUs, joint torque, motor current — which tells the robot about itself, and exteroception — LiDAR, depth, force, GNSS — which tells it about the world. Build proprioception first. A robot that does not know where its own joints are cannot use a good world model anyway.

Typical use: Joint feedback, FOC commutation, dial/knob inputs.

What the numbers actually mean

The headline figure is 12-bit (4096 counts/rev) (resolution), with I²C (also analog / PWM out) as the next most load-bearing number (interface). At $3 in the sensors tier it sits cheap enough to prototype with and replace without regret, which is the correct way to learn a new subsystem.

GotchaAbsolute but not multi-turn — it forgets how many revolutions it has done on power cycle. Add a homing routine or a geared second encoder.

How it compares

Same subsystem, closest alternatives. The primary spec column is usually the one that decides it.

PartPricePrimary specSecond spec
AS5600 magnetic encoderAbsolute rotary encoder $3 12-bit (4096 counts/rev) I²C (also analog / PWM out)
AS5047P magnetic encoderAbsolute rotary encoder $10 14-bit (16384 counts/rev) SPI + ABI quadrature + UVW
CUI AMT102-VCapacitive incremental encoder $25 up to 2048 PPR (configurable) Quadrature A/B/Z
BNO085 9-DOF IMUIMU with onboard fusion $25 3-axis accel + gyro + magnetometer Quaternion / Euler / rotation vector, plus raw
ICM-42688-P6-axis IMU $5 3-axis accel (±16 g) + 3-axis gyro (±2000 °/s) SPI up to 24 MHz, I²C

Where it shows up

It is a component-level choice rather than a defining part of a named platform — pick it for the subsystem it serves, not to match a reference build.