Four phase drive signals for two phase bipolar and four phase unipolar step motors in microcomputer-controlled application is easily implemented using L29 Stepper Motor Controller IC. We can drive the motor in half step, normal and wave drives mode and switch-mode control of the current in the windings is permuted on chip PWM chopper circuits. This device has some features like it requires only clock, direction and mode input signals. Since the phase are produced internally the burden on the microprocessor, and the programmer, is significantly reduced. This device is mounted in DIP20 and SO20 packages. We can use L297 with monolithic bridge drives such as L293E or L298N, or we also can use it with discrete transistors and Darlingtons.
[Source: STMicroelectronics Application Note]