3 *4 KEYPAD INTERFACING WITH ARDUINO

• BOARD -ARDUINO UNO 
• SIMULATION -PROTEUS 8.1

SIMULATION

DOWNLOAD SIMULATION FILES

PROGRAM

#define R1 3   //pin 1
#define R2 4   //pin 2
#define R3 5   //pin 3
#define R4 6   //pin 4
#define C1 7   //pin 5
#define C2 8   //pin 6
#define C3 9   //pin 7
int key=12;
void setup()
{
  // put your setup code here, to run once:
  Serial.begin(9600);
  keypadinit();
}
void loop() {
  // put your main code here, to run repeatedly:
  keycheck();
}
void keycheck(void)
{
  digitalWrite(C1,LOW);digitalWrite(C2,HIGH);digitalWrite(C3,HIGH);//READS FIRST COLUMN
  if(digitalRead(R1)==0) {key=1;}
  if(digitalRead(R2)==0) {key=4;}
  if(digitalRead(R3)==0) {key=7;}
  if(digitalRead(R4)==0) {key=10;}
  digitalWrite(C1,HIGH);digitalWrite(C2,LOW);digitalWrite(C3,HIGH);//READS FIRST COLUMN
  if(digitalRead(R1)==0) {key=2;}
  if(digitalRead(R2)==0) {key=5;}
  if(digitalRead(R3)==0) {key=8;}
  if(digitalRead(R4)==0) {key=0;}
  digitalWrite(C1,HIGH);digitalWrite(C2,HIGH);digitalWrite(C3,LOW);//READS FIRST COLUMN
  if(digitalRead(R1)==0) {key=3;}
  if(digitalRead(R2)==0) {key=6;}
  if(digitalRead(R3)==0) {key=9;}
  if(digitalRead(R4)==0) {key=11;}
  if(key<12) {Serial.println(key); key=12;keydelay();   }
}
//FUNCTIONS
void keypadinit(void)
{
  pinMode(C1,OUTPUT);pinMode(C2,OUTPUT);pinMode(C3,OUTPUT);
  pinMode(R1,INPUT_PULLUP);pinMode(R2,INPUT_PULLUP);pinMode(R3,INPUT_PULLUP);pinMode(R4,INPUT_PULLUP); //pull up
}
void keydelay(void)
{
  delay(300);
}