Arduino Programming using MATLAB, 1st Edition (2015)

3. Working with Digital I/O

In this chapter I'm going to explain how to work with digital I/O on Arduino board and write a program for demo.

3.1 Getting Started

MATLAB support for Arduino board provides three functions which we can use on digital I/O processing. The following is the functions:

· configurePin() is used to define pin mode either as input or output. Reference: http://www.mathworks.com/help/supportpkg/arduinoio/ref/configurepin.html

· writeDigitalPin() is used to write digital data into a specific digital pin. Reference: http://www.mathworks.com/help/supportpkg/arduinoio/ref/writedigitalpin.html

· readDigitalPin() is used to read digital input on specific digital pin. Reference: http://www.mathworks.com/help/supportpkg/arduinoio/ref/readdigitalpin.html

To illustrate how to work with digital I/O, we build a simple program by utilizing LED and pushbutton.

3.2 Demo : LED and Pushbutton

we build a program using LED and pushbutton. When we press a pushbutton, LED will lighting. It's a simple;).

3.2.1 Wiring

The following is hardware wiring:

· LED is connected to Arduino digital pin 9

· Pushbutton is connected to Arduino digital pin 8

A sample of hardware implementation is shown in Figure below.

3.2.2 Writing a Program

Now you can write these scripts.

function [] = led_pushbutton()

pushbutton = 'D8';

led = 'D9';

board = arduino();

finishup = onCleanup(@() exitprogram(board));

configurePin(board,pushbutton,'DigitalInput');

disp('press Ctr-C to exit');

while1

state = readDigitalPin(board,pushbutton);

writeDigitalPin(board,led,state);

disp(state);

pause(0.5);

end

end

functionexitprogram(b)

clear b;

disp('program has exit');

end

We use onCleanup(), http://www.mathworks.com/help/matlab/ref/oncleanup.html , to catch CTRL+C for quiting the program.

Save this program into file, called led_pushbutton.m.

3.2.3 Testing

Run this program by typing this command on Command Window on Matlab.

>> led_pushbutton

Press pushbutton. Then, you should see lighting LED. Press CTRL+C to exit program.

Program output:

LED is lighting while a pushbutton is pressed.