Product Details An independent button is also called a tap switch, which is used do press the direction of operation of the switch to meet the working force conditions, and the switch is closed and connected. After the pressure is withdrawn, the switch is disconnected, and its internal structure is realized by changing the force of the metal shard. In the following four-pin circuit diagram, it is clear that under normal conditions pins 1 and 2, 3 and 4 of the key are connected; when the button is pressed, four legs connect to each other; when the key is released, the normal state is restored. Key control can be implemented using digital inputs/outputs. The meaning of digital I/O port is INPUT and OUTPUT interfaces. Now let's try to use the INPUT I/O function in Arduino, which is the function of reading output values from external devices in this experiment. We used the buttons and LED lights to complete the experiment using a combination of INPUT and OUTPUT. Our key module sends a low level when you press the key and a high level when you release the key. Pin name Description G GND (negative power input) V VCC (positive power input) 1 Pin digital signal 2 Digital signal contacts 3 Digital signal contacts 4 Digital signal contacts Module parameter Supply Voltage: 3,3 V/5 V Connection mode: row of pins 2,54 mm Installation Method: Double Screw Fastening