Computer Architecture and Organization

Introduction to the Arduino Microcomputer

Equipment: Arduino UNO microcomputer, PC with Arduino IDE installed, and a

USB cable. Prototyping components and wires.

The Arduino microcomputer is a low end microprocessor on a small printed circuit board. In our

lab configuration, it includes a small breadboard for prototyping and connecting peripherals.

You will use the Arduino.exe IDE program to edit, compile, download, and monitor the

execution of your $$sketches$.$ Arduino control software is written in a language that is almost

exactly like C$.$ There are a few extensions to the language and a custom library to access the

peripheral hardware input and output ports.

Your first assignment is to set up your Arduino system and run the example $$Blink$$ program.

Connect the PC to the Arduino UNO board using the USB cable. Open the Arduino.exe

program. Use the menu: File $>>$ Examples $>>01.$ Basic. Select the Blink program which will

open a new window containing the source code for the Blink program. Use the $$right arrow$$

icon on the top tool bar to compile and upload$/$run the code on the Arduino board. Watch the

LED$$s on the Arduino board during the upload to observe it occurring. Once the program starts

running, the yellow LED will be flashing at a rate of one second on and one second off.

Now study the code in the source of the sketch. Find the lines that control the flash rate for the

blinking LED. Change those lines to slow down the flash rate to one half of the current

rate. Repeat the steps for compiling, uploading, and running your modified code. Show the TA

when you have this working.

Now disconnect the Arduino board from the USB port. NOTE: When you are adding, changing,

or removing wiring on a prototype connected to the Arduino UNO board, always disconnect the

power from the USB port and check your wiring carefully before reconnecting it to the USB

port. Otherwise, you may damage the Arduino board. If you have any doubts, show your wiring

to the TA before reconnecting it to the USB port.

Insert an LED and a resistor in series on the breadboard to pin $12$ on the Arduino board

following the design shown in this picture. The longer leg on the LED should be connected to

the resistor.

The resistor should be $470$ ohms which you can determine from the color of the bands around the

body of the resistor $($yellow$,$ violet, brown$).$ See the standard resistor color code table:

First Band Second Band Third Band

Black $00$ no zeros

Brown $11$ one zero

Red $22$ two zeros

Orange $33$ three zeros

Yellow $44$ four zeros

Green $55$ five zeros

Blue $66$ six zeros

Violet $77$ seven zeros

Gray $88$ eight zeros

White $99$ nine zeros

Again study the code in the source of the sketch. Find the line$($s$)$ that control the pin being used

to flash the LED. Change the line$($s$)$ to use pin$12$ instead of pin $13$ to flash the LED on your

breadboard. Repeat the steps for compiling, uploading, and running your modified code. Show

the TA when you have this working.

Naturally, you want to run your embedded system without an $$umbilical cord$$ to a development

station. A mobile device usually has its code stored in a non$-$volatile memory and is battery

powered. Disconnect the Arduino from the USB cable. Plug the battery pigtail into the

connector next to the USB connector on the Arduino board. It should power up and run your

sketch independently. Now it is portable.

DISCONNECT THE BATTERY PIGTAIL BEFORE PUTTING THE KIT BACK IN THE

STORAGE CONTAINER.

As a team, write your lab report to explain what you did, how you did it$,$ and what you learned

about interfacing hardware to a microprocessor and its software $($the $$sketch$).$ Post your report

in Moodle.

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