Precise speed control is an important requirement for efficient industrial automation. Direct current (DC) motors have been extensively used for this purpose. The conventional method employs analog circuits to control the speed of the DC motor by varying the voltage of the armature while the field voltage is kept constant. In this paper, a digital speed control of DC motor using pulse width modulation technique was implemented by replacing analog circuit with an Atmel AT89S52 microcontroller circuit. An experimentation of the design showed that the DC motor can run forward motoring, forward regeneration, reverse motoring and reverse regeneration. This digital approach proved to have increased precision and greater control efficiency. Thus, a centralized control of several motors can also be achieve
