SPECIFICATIONS

Brand Name: NoEnName_Null
Origin: Mainland China

4 Key Mcu Keyboard Matrix for Arduiuo DC 0-48V Push Button Switch MEGA2560 DUE Button Breadboard Switch FPGA CPLD STM32 2PCS 

Specifications:
Can be inserted directly into Arduiuo uno mega2560,Ideal for linking up to your Arduiuo UNO Pro Mini Nano Mega2560 Breadboard raspberry pi etc,or others MCU ( PLC AVR STM32 ARM PIC AT89C51 MSP430 STM8 Xilinx Altera Lattice FPGA CPLD etc.)

1. 4-button Common Cathode key module .
2. " GND K1 K2 K3 K4" 4 PIN OUT 2.54mm
3.  Working voltage: Can be DC 1.2V 1.8V 2.5V 3V 3.3V 4.5V 5V 9V 12V 24V 36V 48V 
4. Size: 12.7MM x 33MM.

Arduiuo uno/mega2560 Code

//******************************************************//

/*
Arduiuo_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() {
// 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 resistors
digitalWrite(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);//Wait button release

buttonState = digitalRead(K4);
if(!buttonState)Serial.print("k4 \n" );
do
{
buttonState = digitalRead(K4);
}
while(!buttonState);//Wait button release

delay(100);
}

 //******************************************************//


Note:
1. Due to the light and screen difference, the item's color may be slightly different from the pictures.
2. Please allow 1mm-1cm differences due to manual measurement.

Package Included:
1x 4 Key Mcu Keyboard