Control of Stepper Motor Using Microcontroller

Control of Stepper motor using microcontroller At the heart of the Stepper Motor Controller is AT89C51 micro-controller. From traffic control equipment to input devices, computer networking products and stepper motor controllers, 89C51 microcontrollers deliver a high performance with a choice of configurations and options matched to the specific needs of each application. In the Stepper Motor Controller circuit, the control switches for the motor are connected to Reset and Port P0.7 pins of the microcontroller while the stepper motor is connected to port pins P2.4 through P2.7 of the microcontroller (IC2) through the motor-driver circuit consisting of four Darlington pairs comprising transistors BC548 and SL100 (T1-T2, T3-T4, T5-T6 and T7-T8). When transistors conduct, 5V (Vcc) is applied to the coils of the motor and the currents flowing through them create magnetic fields and the motor starts rotating. The magnetic field energy thus created is stored in the coils. When transistors stop conducting, power to the coils is cut off, the magnetic field collapses and a reverse voltage (called inductive kickback or back emf) is generated in the coils. The back emf can be more than 100 volts. The diodes connected across the coils absorb the reverse voltage spike.