This project was developed as an inexpensive way to drive small dc brushed motors as positioning servos for use on a desktop sized CNC machine. The board is interfaced to the PC through 2 pins of a parallel port. The drive signal on these pins is known as quadrature drive. The power stage consists of a power op amp driven in constant current mode. The internal PIC processor ( a 30f4012 from Microchip ) is programmed in C through the C30 compiler and the Microchip IDE. The servo loop parameters are programmed through a serial port connection and are saved in the dspic eeprom. Once set for a particular drive, they should not need to be changed.
http://www.youtube.com/watch?v=RJEXbEXn0CQ
http://members.shaw.ca/swstuff/dspic-servo.html
