Keypad Interfacing with Arduino Uno
Keypad Interfacing with Arduino
Uno
In
this tutorial we are going to interface a 4x4 (16 key) keypad with ARDUINO UNO. We all know keypad is one of the most important
input devices used in electronics engineering. Keypad is the easiest and the cheapest way to give
commands or instructions to an electronic system. Whenever a key is pressed in keypad module
the Arduino Uno detects it and shoes the corresponding key on 16x2 LCD. [Also check: Keypad
Interfacing with 8051 Microcontroller]
Components Required
Hardware: ARDUINO UNO, power supply (5v),
100uF capacitor , buttons (two
pieces), 1KΩ resistor (two pieces), 4x4
Keypad Module, LED, JHD_162ALCD (16x2LCD).
Software: arduino IDE (Arduino nightly).
Circuit Diagram and Working Explanation
In
16x2 LCD there are 16 pins over all if there is a back light, if there is no
back light there will be 14 pins. One
can power or leave the back light pins. Now in the 14 pins there are 8 data pins (7-14 or
D0-D7), 2
power supply pins (1&2 or VSS&VDD or
GND&+5v), 3rd pin for contrast control (VEE-controls
how thick the characters should be shown) and 3 control pins (RS&RW&E).
In
the Arduino uno keypad interfacing circuit, you can observe
that I have only took two control pins. This give the flexibility of better understanding,
the contrast bit and READ/WRITE
are not often used so they can be shorted to ground. This puts LCD in highest contrast and read mode. We just need to control ENABLE and RS pins to send
characters and data accordingly. [Also
check: 16x2
LCD Interfacing with Arduino Uno]
The
connections which are done for LCD are given below:
PIN1
or VSS to ground
PIN2
or VDD or VCC to +5v power
PIN3
or VEE to ground (gives maximum contrast best for a beginner)
PIN4
or RS (Register Selection) to PIN8 of ARDUINO UNO
PIN5
or RW (Read/Write) to ground (puts LCD in read mode eases the communication for user)
PIN6
or E (Enable) to
PIN9 of ARDUINO UNO
PIN11
or D4 to PIN10 of ARDUINO UNO
PIN12
or D5 to PIN11 of ARDUINO UNO
PIN13
or D6 to PIN12 of ARDUINO UNO
PIN14
or D7 to PIN13 of ARDUINO UNO
We are
going to connect the keypad module between pins 0-7 of Arduino Uno, as shown in the circuit diagram. All the eight pins of keypad module are connected
accordingly.
Now
for setting up a connection between Keypad Module and UNO, we need to get the
keypad library from the ARDUINO website. After that we can directly call the header file. We will discuss each command below.
1.
#include <Keypad.h>
2.
const byte ROWS = 4; // Four rows
3.
const byte COLS = 4; // Three columns
// Define the Keymap
1.
char keys[ROWS][COLS] = {
{'1','2','3','A'},
{'4','5','6','B'},
{'7','8','9','C'},
{'#','0','*','D'}
};
// Connect keypad
ROW0, ROW1, ROW2 and ROW3 to these Arduino pins.
1.
byte rowPins[ROWS] = { 0, 1, 2, 3 };
// Connect keypad
COL0, COL1 and COL2 to these Arduino pins.
1.
byte colPins[COLS] = { 4, 5, 6, 7 };
// Create the Keypad
1.
Keypad kpd = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
2.
char key = kpd.getKey();
|
First
we will call the header file which enables user to access all keypad commands. We will write each key of keypad in matrix,
for the UNO to understand the key press.
Telling
the Uno which pins are used to connect the keypad module.
Telling
the UNO to map each key on press.
Getting
the UNO mapped key in to a memory.
The
working of Arduino Uno Keypad Interface is best explained in C code
given below.
Keypad Interfacing with Arduino Uno
Reviewed by XXX
on
สิงหาคม 27, 2560
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