4x4 Matrix Keypad
16 buttons read through just 8 pins as a row/column grid.
How it works
A matrix keypad wires its buttons in a grid so 16 keys need only 8 pins (4 rows + 4 columns) instead of 16. The Arduino scans it: drive one row at a time and read which column responds to find the pressed key.
The Keypad library does all the scanning — you just map the grid to characters and call getKey().
Pins
- R1–R4
- Row pins — to four digital pins.
- C1–C4
- Column pins — to four digital pins.
Ratings
- Keys
- 16 (4×4)
- Pins
- 8 (4 rows + 4 columns)
Tips
- Use the Keypad library and define the key layout in code.
- Pin order along the connector varies — check your keypad before wiring.