GERBER PCB:

https://mega.nz/file/iBInRDaZ#UM1zr_WqdQiTgqlQLhWYgdXwZUa404LIk4jIMSq-orY

KEYPAD KEYBOARD

The Plastic Button Matrix Keyboard made up of 4 rows and 4 columns for a total of 16 keys allows you to add user input to your projects. The keyboard is membrane type, so among its advantages is the little space it requires to be installed. It has an adhesive cover and a flexible connection cable. It can be connected to any microcontroller or development boards like Arduino.

The 4x4 matrix keyboard is made up of a matrix of buttons arranged in rows (L1, L2, L3, L4) and columns (C1, C2, C3, C4), with the intention of reducing the number of pins necessary for its connection. The 16 keys require only 8 microcontroller pins instead of the 16 pins that would be required for connecting 16 independent keys. In order to read which key has been pressed, a scanning technique must be used and not just read a microcontroller pin.

Connecting the 4x4 matrix keyboard with Arduino or other microcontroller platform is simple: 8 digital pins in total are needed. It can work with 3.3V or 5V microcontrollers without problem. It is necessary to put pull-up resistors between the column pins and VCC or to software-enable the internal pull-up resistors on the Arduino. Regarding programming, the reading of the keys must be done by "scanning" the rows. Although it is possible to carry out this procedure within the main loop of the program, it is a better practice to carry out the sweep using TIMER interrupts and thus ensure the reading of the keys in a known and exact interval, in addition to leaving the loop free to perform other operations.

Technical specifications

•      9 buttons with matrix organization (3 rows x 3 columns)

•      Membrane type keyboard

•      Greater resistance to water and dust

•      Self adhesive on the back

•      Bounce time: ≤5ms

•      Maximum operating voltage: 24 V DC

•      Maximum operating current: 30 mA

•      Insulation resistance: 100 MΩ (@ 100 V)

•      Dielectric withstand voltage: 250 VRMS (@ 60Hz, for 1 min)

•      Life expectancy: 1,000,000 operations

•      Keyboard dimensions: 69*77mm

•      Flat ribbon cable approx. 8.5 cm long. (including connector)

•      DuPont type connector single row and 8 contacts with standard separation 0.1" (2.54mm)

•      Operating temperature: 0 to 50 °C

Applications:

•      Security systems

•      Menu selection

•      Data entry

Electronic components:

•      3 resistors 1/4w 220 ohm

•      9 push-button

•      3 diodes 5mm any color

•      1 sprat (40 pins)

•      1PCB

Project features:

•      VIN 5V

•      3 DIGITAL OUTPUTS

•      3X3 MATRIX KEYBOARD

•      IMAX 100mA

•      4-digit or 6-digit password

#include <Keypad.h>     // importa libreria Keypad


const byte FILAS = 3;     // define numero de filas
const byte COLUMNAS = 3;    // define numero de columnas
char keys[FILAS][COLUMNAS] = {    // define la distribucion de teclas
  {'1','2','3'},
  {'4','5','6'},
  {'7','8','9'},
};


byte pinesFilas[FILAS] = {7,6,5}; ...