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4x4 Membrane Keypad

Control

Thin, 16-key keypad with an adhesive back, with the digits 0-9, the letters A-D, and the * and # keys; for coded locks, entry panels and calculator projects. The keys are wired as a matrix of 4 rows and 4 columns: its 8 wires plug straight into 8 digital pins, and it needs no power supply. The Keypad library finds which key is pressed. With an LCD on an Uno you may run out of pins; prefer an I2C LCD.

Specifications

Keys

16 (0-9, A-D, *, #)

Layout

4 x 4 matrix (4 rows, 4 columns)

Connector

8-pin female header, 2.54 mm

Pins used

8 digital pins, no power needed

Rating

24V DC, 30 mA

Size

~77 x 70 mm, ~1 mm thick

Mounting

Adhesive back

Library

Keypad (Mark Stanley, Alexander Brevig)

Shop prices

• RobocomboIn stock33.00 ₺
• ElektrovadiIn stock33.07 ₺
• SAMM MarketIn stock35.72 ₺
• MotorobitIn stock41.92 ₺
• HatfonIn stock42.87 ₺
• Robo90In stock43.45 ₺
• Robolink MarketIn stock49.50 ₺
• HobiDevreIn stock50.88 ₺
• KomponentciIn stock58.71 ₺
• RobotistanIn stock59.34 ₺
• Modül ElektronikIn stock64.61 ₺
• RobotsepetiIn stock67.05 ₺
• RobotzadeIn stock84.00 ₺
• F1 DepoOut of stock21.00 ₺
• Direnc.netOut of stock52.31 ₺

Prices read from the shops' pages on 22 October 2026. Prices and stock may have changed since; check at the shop before you buy.

Projects with this part

• Code Door LockIntermediate50 minA door lock that opens with a code typed on a 4x4 keypad: the LCD says what to do and shows the digits as *, and when the code is right the servo turns the latch and opens the door for 5 seconds while the screen counts down. After 3 wrong codes in a row the keypad is locked for 30 seconds. While the door is open, A changes the code; the new code is typed twice and saved in the Arduino's EEPROM memory, so it is kept even if the power goes. It teaches reading a keypad as a matrix, splitting a program into states (locked, open, waiting, changing the code), listening to keys while timing with millis(), and using memory that lasts. Install "Keypad" and "LiquidCrystal I2C" from the Library Manager; Servo and EEPROM come with the Arduino IDE. This is a learning project; do not use it as a real door's only lock.Open project