Abstract : This paper introduces the dual four-phase control method of stepper motors using an 8031 ​​microcontroller, as well as common problems and solutions. Keywords : stepper motor; step angle; microcontroller. Stepper motors are numerically controlled motors and are one of the commonly used control components in industrial control and instrumentation. Their most significant characteristic is that they are controlled by input pulse signals; that is, the total rotation angle of the motor is determined by the number of input pulses, while the motor speed is determined by the pulse signal frequency. It has the characteristic that the input pulse is proportional to the motor shaft rotation angle, converting the pulse signal into angular displacement. That is, for every pulse signal, the stepper motor rotates by one angle, making it very suitable for microcontroller control. 1. Dual Four-Phase Control Method for Stepper Motors When a stepper motor operates in dual four-phase mode, following the AB, BC, CD, DA pattern, only two phases are always energized (see Table 1). The current passing through it is twice that of single-phase energization, and the torque is also twice that of single-phase energization. At this time, the motor vibration is smaller and the response frequency is higher, so this design adopts this method. [b][align=center]For detailed information, please click to download: Implementation of Stepper Motor Control using MCS-51 Microcontroller[/align][/b]