20pcs Keypad 4 Button Key Module Switch Keyboard For UNO MEGA2560 Breadboard

Description Can be inserted directly into uno mega2560 Ideal for linking up to yourUNO Mini Nano Mega2560 Breadboard etc or others MCU AVR STM32 ARM PIC AT89C51 STC MSP430 STM8 FPGA CPLD etc 4 button Common Cathode key moduleGND K1 K2 K3 K4 4 PIN OUT 2 54mmSize 12 7MM x 33MM Circuit schematics Package includes 20 x Keyboarduno mega2560 Code 4key uart This 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 status 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 release buttonState digitalRead K2 if buttonState Serial print k2 n do buttonState digitalRead K2 while buttonState Wait button release buttonState digitalRead K3 if buttonState Serial print k3 n do buttonState digitalRead K3 while buttonState Wai