Q-Pixie is a tiny closed loop position/velocity controller with quadrature feedback and configurable velocity/acceleration/power limiting that solders straight onto a N20 gearmotor.

Q-Pixie is based on the QuadQuad2Drv and features the same interface and protocol.

The board reads position and velocity information from the on-board incremental quadrature encoder and performs closed loop control on the DC motor. Communication is via SPI interface and allows configuration, commands and reading back information.

Measurement Features

  • Quadrature feedback (sampled 4x per detent)
  • Provides position (8, 16 or 32-bit), velocity, status and timing metadata
  • Velocity up to 50,000 transitions/s with resolution of 4 transitions/s
  • Home/index and edge inputs; can be used to read end-stops

Control Features

  • Motor power up to 11V, 1.8A (peak)
  • Power, position and velocity control modes using PID
  • Power, velocity and acceleration limiting (configurable)
  • Position and velocity ramp commands
  • Loop rate of 500Hz

Misc Features

  • Includes magnet wheel to press onto rear motor shaft
  • SPI slave interface
  • Streamed or polled data packets
  • Operating voltage 3.3V with 5V tolerant SPI pins
  • Molex Picoblade 15-way connector
  • Dimensions: 27mm x 20mm
  • Bootloader for firmware updates via UART serial
  • Arduino library and demo available
  • PIC library available on request

The PCB comes with an optional Molex Picoblade 15-way connector, allowing for connection with an Arduino or other controller. A complete Arduino library and demo code is available for free, as well as a datasheet detailing physical connections and protocol.


Drivers and Demos