use: 1. +5 +5 is the positive input port of the power supply, which can be connected to a voltage of 3.3V~5V 2. GND GND is the negative input port of the power supply. OUT OUT is the signal output port, which is connected to the I/O port of the single-chip microcomputer. Generally, it is connected to an external interrupt. For other main control boards or higher-level main control boards (such as Arm), if you need to set the I/O port to input/output mode, you must set it to input mode/receive mode, otherwise it cannot be used. 51 series MCU can be used directly, no need to set input and output mode Note: For Arduino players should set the MCU's I/O port to input mode/receive mode, otherwise it cannot be used.