20pcs TB371 4 Key MCU Keyboard Button Board Compatible UNO MEGA2560 Pro Mini Nano Due for Raspberry Pi Teensy++ Geekcrei

Description 1 4 button Common Cathode key module When pressed output low level 2 GND K1 K2 K3 K4 4 PIN OUT2 54mm3 Working voltage DC 0 48V 4 Size 12 7 x 33mm5 It can be inserted directly into Arduiuo uno3 mega2560 due for linking up to yourArduiuo uno3 Mini Nano Mega2560 Breadboard for raspberry pi banana pietc or others MCU PLD CPU AVR STM32 ARM PIC C51 NRF24LE1 CC2530 MSP430 STM8 FPGA CPLD etc Circuit schematics Arduiuo uno3 mega2560 Code Arduiuo 4key uartThis example code is in the public domain Define key pinint K1 13 int K2 12 int K3 11 int K4 10 variables will change int buttonState 0 variable for reading the pushbutton the setup routine runs once when you press reset void setup initialize the keys pin as an input pinMode K1 INPUT pinMode K2 INPUT pinMode K3 INPUT pinMode K4 INPUT Activate key pin internal pull up resistorsdigitalWrite K1 HIGH digitalWrite K2 HIGH digitalWrite K3 HIGH digitalWrite K4 HIGH initialize serial communications at 9600 bps Serial begin 9600 the loop routine runs over and over again forever void loop buttonState digitalRead K1 if buttonState Serial print k1 n do buttonState digitalRead K1 while buttonState Wait button releasebuttonState digitalRead K2 if buttonState Serial print k2 n do buttonState digitalRead K2 while buttonState Wait button releasebuttonState digitalRead