Keypad 4 Button Key Module Switch Keyboard for UNO MEGA2560 Breadboard

Description
Can be inserted directly into uno mega2560, Ideal for linking up to your UNO Mini Nano Mega2560 Breadboard etc, or others MCU ( AVR STM32 ARM PIC AT89C51 STC MSP430 STM8 FPGA CPLD etc.)
4-button Common Cathode key module
GND inchK1 K2 K3 K4inch 4 PIN OUT 2.54mm
Size:12.7MM x 33MM.
Circuit schematics
Package includes
1 x Keyboard
uno/mega2560 Code
//******************************************************//
/*
_4key_uart
This example code is in the public domain.
*/
// Define key pin
int 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()
// the loop routine runs over and over again forever
void loop()
while(!buttonState);//Wait button release
buttonState = digitalRead(K2);
if(!buttonState)Serial.print(inchk2 ninch );
do
while(!buttonState);//Wait button release
buttonState = digitalRead(K3);
if(!buttonState)Serial.print(inchk3 ninch );
do
while(!buttonState);//Wait button release
buttonState = digitalRead(K4);
if(!buttonState)Serial.print(inchk4 ninch );
do
while(!buttonState);//Wait button release
delay(100);
}
//******************************************************//

Additional information