Active buzzer features are: 1 active buzzer with internal shock source, so as long as a power will be called 2 program control is convenient, a high and low level of the microcontroller can let it sound, and passive buzzer can not do. -module interface description (3-wire) 1 + external 3.3V-5V voltage (can be directly connected with the 5v microcontroller and 3.3v microcontroller) 2 - external GND3 out external microcontroller IO port