One is that the single chip microcomputer outputs a voltage (through DA chip or PWM mode) as the reference voltage of the power supply. This mode only replaces the original reference voltage with a single chip microcomputer, and the output voltage of the power supply can be input by pressing the key. The single chip microcomputer has not added the feedback loop of the power supply, and the power supply circuit has not been changed. This model is the simplest. The other is to continuously detect the output voltage of power supply by expanding AD with single chip microcomputer. According to the difference between the output voltage of the power supply and the set value, the output of DA is adjusted, the PWM chip is controlled, and the power supply is indirectly controlled. In this way, a single-chip microcomputer is added to the feedback loop of the power supply to replace the original comparative amplification link, and the program of the single-chip microcomputer should adopt a more complicated PID algorithm. Thirdly, the single chip microcomputer expands AD, constantly detects the output voltage of the power supply, and outputs PWM wave according to the difference between the output voltage of the power supply and the set value, thus directly controlling the power supply. In this way, the single chip microcomputer participates in the power supply work the most.