Quadrature XB

A precision, high-performance quadrature interface!

A quadrature encoder provides the ability to measure the behavior of a rotating shaft.  The encoder generates 2 outputs that are sampled to calculate speed, direction and position of the shaft.  This information can be used for harvesting valuable information about wheels, knobs, or other actuators connected to the motor shaft. 

Encoder outputs are often decoded by using a software interrupt routine.  At high speeds or high resolution, however, a software-based microcontroller can be quickly overwhelmed by the rapid stream of interrupts that need to be processed.

Alorium Technology’s Quadrature XB moves this operation into custom hardware on the FPGA providing the following key benefits:

  • Guaranteed edge capture
  • Much higher sampling rates
  • Independence from interrupt service routines of the microcontroller
  • Improved microcontroller performance through quadrature offload


  • 1.6 million ticks per second maximum input from a quadrature encoder
  • 16 bit rate, 24 bit distance counters, implemented as signed integers to account for directionality
  • Programmable interval for measuring rate and count: 20ms or 200ms
Required Alorium Technology library:  XLR8Quadrature Supported XLR8 Images:
  • 16MHz Robotics: Servo, Quad
  • 32MHz Robotics: Servo, Quad