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The 4x4 keypad is a composite of 16 keys arranged like a matrix. The method used for accessing 4x4 keypad with matrix scanning method. The 4x4 keypad requires 8 pins to access it, ie 4 pins for the columns and 4 pins for the line. How the scanning method works is that the column pin takes the LOW logic interchangeably, then the line pin performs the readings in turn as well.

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You will need:

• Arduino
• Jumper Wires

Step 2: Pin Out

1. PIN A3 --> pin to 0 row
2. PIN A2 --> pin to 1 row
3. PIN A1 --> pin to 2 row
4. PIN A0 --> pin to 3 row
5. PIN 4 --> pin to 0 colomn
6. PIN 5 --> pin to 1 colomn
7. PIN 6 --> pin to 2 colomn
8. PIN 7 --> pin to 3 colomn

Step 3: Schematic

Connect each component as the picture above.

Step 4: Code

`#include <Keypad.h> //import library keypad`
```const byte ROWS = 4; //number of colomn
const byte COLS = 4; //number of row
char hexaKeys[ROWS][COLS] = {
{'1','2','3','A'},
{'4','5','6','B'},
{'7','8','9','C'},
{'*','0','#','D'}
};
byte rowPins[ROWS] = {A3, A2, A1, A0}; //pin used for row
byte colPins[COLS] = {4, 5, 6, 7}; //pin used for colomn```
```//initialization variable
```void setup(){
Serial.begin(9600);
}

void loop(){

if (customKey){
Serial.println(customKey);
}
}```

Step 5: Output

Check the output!

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