Retired Product

This product has been retired from our catalog and is no longer for sale. This page is made available for those looking for datasheets and the simply curious.

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Description: This quadrature encoder board is designed to hold two infrared reflectance sensors inside the hub of the 42x19mm wheel and measure 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 the board 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 3.3V .

The two outputs of the encoder are digital outputs that can be connected directly to digital input pins on most microcontrollers (inputs that can generate interrupts on change are recommended). With 48 state changes per revolution of the 42 mm wheel, a speed of 1 m/s (a bit over 3 feet per second) generates approximately 360 state changes per second. With two encoders used simultaneously, as is the case for most differential-drive robots, the encoders will require attention almost every millisecond. Decoding the encoder outputs should only take a few percent of the processing power of a microcontroller such as the Atmel ATMega168.


  • 4.5-5.5V operating voltage
  • 2 digital outputs
  • 14mA consumption at 5V
  • 48 counts per revolution (linear resolution just under 3mm)
  • 2A continuous paralleled output current
  • 100kHz maximum PWM frequency
  • 2.7-5.5VDC logic voltage

Dimensions: 1.6g


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Customer Comments

  • 2A continuous paralleled output current? What is this talking about?

  • I think it’s accidentally copied over from the 1 amp dual motor driver specs.

  • does anyone have another suggestion for a general purpose rotary encoder?
    learned movements are so interesting!

  • Can this encoder be used at a higher resolution or is it specifically designed for the wheel? (i.e. If I make my own wheel with 32 16 counts per tooth or something like that?)

    • It’s possible, but I think it would be very difficult to get something working well. To get a working quadrature encoder, you will need to set up the your wheel so the teeth generate signals approximately 90 degrees out of phase. The height and thickness will also probably affect the results. Pololu has a schematic of the board if you want to better understand how it works.

  • See the instructions at the bottom of this page, under the section titled “Modifying the Encoder for 3.3 V Operation”.

  • Is shorting R4 all that is need to make this encoder work at 3.3v?
    It also mentions recalibration. How do I do that?

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