Stepper Motor Driver Controlled by PC

Figure 1 

The project illustrates the control of two unipolar stepper motors using this circuit in full step mode through the RS232 serial port of the PC.

The signals from the serial port of the PC is being converted to the TTL level of the AVR microcontroller using a MAX232 IC. The signals are taken from the serial port using an ATtiny2313 microcontroller as well as to translate the signals to drive the coils of the stepper motor. The ULN2803A amplifies the signals from the microcontroller and is configured in a Darlington array where loads up to 500mA are being driven.

TTL level is it’s input and the output is up to 30VDC. The stepper motor is driven in full step mode where the two windings are energized for every step. By sending commands to the board with the terminal program, the motor can be rotated left and right. Each command can make a maximum of 3200 steps.

A terminal program such as HyperTerminal is required to run the stepper motor. There is a setting for synchronizing the terminal program with the stepper board and there are 4 commands sent to the stepper controller.

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