The Phidgets 3303_0 is a stepper motor controller board that can drive up to two bipolar or four unipolar stepper motors with currents up to 1.5A per coil. It uses the A4988 stepper motor driver chip and includes screw terminals for easy motor connection. The board allows control of speed and direction of the stepper motors through a USB or serial interface.

7. http://www.phidgets.com/products.php?product_id=3303_0

9. http://bwhoward.com/additive-rapid-prototyper-project-news-andupdates/2013/5/29/electronics-pololu-a4988-stepper-motor-driver
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