CS 341 – Lab 1
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.
In our lab, the Arduino UNO will be the target host for our experiments and the PC attached to it via the USB cable will be the development host. You will use the Arduino.exe IDE program to edit, compile, download, and monitor the execution of your “sketches” (experimental programs). The “sketch” 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 0 0 no zeros
Brown 1 1 one zero
Red 2 2 two zeros
Orange 3 3 three zeros
Yellow 4 4 four zeros
Green 5 5 five zeros
Blue 6 6 six zeros
Violet 7 7 seven zeros
Gray 8 8 eight zeros
White 9 9 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 pin12 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”). Turn in your report at your next lab session.
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