1.[Calibration function]: The tester calibration is used to eliminate the errors of its own components to make the final test results more accurate. Calibration is divided into quick calibration and full-function calibration. Full-function calibration can be entered from the function menu and requires an additional 220nF power supply. 2.[Frequency measurement]: The frequency measurement range is from 1Hz to above 1. When the measured frequency is lower than 25KHz, the period is displayed. 3.[Square wave generator]: Square wave generator, a variety of square wave frequencies are optional, rotating the test button left and right can switch between different square wave frequencies, and long pressing the test button to exit the square wave generator. 4.[10-bit PWM]: Pulse generator, rotating the test button left and right can adjust the duty cycle of the pulse, ranging from 1%-99%. Long pressing the test button to exit the pulse generator.