4×4 Membrane Keypad
by Generic
SKU: PSA-CMP-KEYPAD44
No reviews yetTypical India street price
₹40–₹90
0–9 * # ABCD keys for PINs, menus, calculators.
Interface: 8 GPIO (matrix scan)
Momentary switch into the kit button input (usually active LOW with pull-up).
Signal → D3 (GPIO0)
Blockly: sense_button
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Concept
A switch matrix: 4 rows × 4 columns, 8 wires not 16.
A little theory
Drive one row LOW, read columns. Diodes not needed at 4×4 hobby current. In the classroom, treat 4×4 Membrane Keypad as a beginner part using 8 GPIO (matrix scan). Typical India street price is about ₹40–₹90. Always verify voltage and pin labels on your exact module — silk screens vary across clones. Start with a datasheet or trusted learn guide, power the part correctly, share GND with the MCU, and test with a simple blink/read sketch before building the full project. Measure voltages with a multimeter when something fails, and keep actuator current off the MCU regulator.
How it works in a project
Keypad.h or manual scan with pull-ups on columns.
Classroom & project use
- Door lock demo
- Calculator
- Quiz buzzer codes
Buying in India
Precautions
- Share a common GND with the microcontroller
- Verify polarity and voltage before powering the circuit
Specifications
| Layout | 4x4 |
| Keys | 16 |
| Category | Sensors |
| Difficulty | Beginner |
| Voltage | 3.3–5V |
| Interface | 8 GPIO (matrix scan) |
Pinout
See module silkscreen: typically VCC, GND, and signal pins. Confirm labels against the seller photo — clones vary.
