Encoder for Pololu Wheel 42x19mm is designed to work with Pololu micro metal gearmotors by holding two infrared reflectance sensors inside the hub of a Pololu 42×19mm wheel and measuring the movement of the twelve teeth along the wheel’s rim. The two sensors are spaced to provide waveforms approximately 90 degrees out of phase, allowing the direction of rotation to be determined and providing four counts per tooth for a resolution of 48 counts per wheel rotation. Each analog sensor signal is fed to a comparator with hysteresis to provide glitch-free digital outputs. The compact layout of Encoder for Pololu Wheel 42x19mm fits all of the components within the envelope of the hub and tire, allowing the board to be mounted between the motor and a chassis. The encoder is calibrated for operation from 4.5 V to 5.5 V, but it can be recalibrated for operation at 3.3 V.
Pololu AVR C/C++ Library User’s Guide: https://www.pololu.com/docs/0J20
Pololu AVR Library Command Reference: https://www.pololu.com/docs/0J18
Pololu Web Site: https://www.pololu.com/product/1217