This document provides instructions for building an ATTiny light sculpture using a small and inexpensive ATTiny85 microcontroller chip. It explains that the ATTiny85 has fewer pins than the Arduino Uno but is sufficient for most basic projects. It outlines how to program the ATTiny85 chip using the Arduino IDE by selecting the correct board and programmer settings. Example blinking LED code is provided and explained. Challenges are given to modify the code to change the blink rate and create heartbeat and Morse code patterns.

1. Name: _______________________________ Date: ___________
Build your own ATTiny Light Sculpture!
Part I
Introduction
Using a programmable microcontroller, let’s see how you can combine color, shape, form,
and space to create your own works of art!
Traditionally, many have created projects like this using a full-blown Arduino - a
microcontroller capable of handling lots of different inputs or outputs. These are great, but
still somewhat costly (~$20). So instead, we are going to use the ATTiny85, the little sister to
the Arduino Uno.
ATtiny85 vs. Arduino Uno
The ATTiny85 is...well, tiny! It is a single programmable chip
that consists of just 8 pins -- 5 of which are controllable. This
means we can write programs / code that control the
behavior of these pins to turn LEDs ON or OFF, read
sensors, or move motors! What makes it real nice is that it’s
a self contained controller. All we need to do is hook up
power to it.
The Arduino Uno (or the SparkFun RedBoard) uses the ATMega328 microcontroller. This
chip has 32 pins -- 20 of which are controllable! The Arduino Uno also has a lot of extra
supporting hardware on-board including a voltage regulator, oscillator crystal, a
programmer, and a hand-full of other components. While these are nice to have, for most
projects, the ATTiny is perfect!
ATTiny85 Pins
The ATTiny85 has 8 pins in total -- 4 on each side. The pins are designated as
follows. Look at the top of the chip closely. Notice that there is a either a notch
or a small dot near one side? This indicates the “up” direction on the chip.
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2. For the chip to operate, we need to supply power to it. Connect the positive side of your
power supply to VCC and the negative side to GND. The ATTiny can handle voltages
between 1.8 - 5.5 VDC.
The remaining pins -- labeled 0, 1, 2, 3, & 4 -- are programmable. Using the Arduino
programming environment, we can write code that will control the voltage to these pins. The
last pin, labeled ​Reset​, is for exactly that. When this pin is connected to ground (GND), the
chip resets. For now, we’re just going to leave this one alone.
Let’s get coding!
Open up the Arduino IDE (Integrated
Development Environment). The icon
should looks similar to this symbol here.
Before we write any code, let’s first configure the
programming environment. First, let’s set up the
board type.
Click on the ​Tools Menu → Board → ATtiny85
(internal 1 MHz clock)​.
Next, configure the Programmer. Click on the
Tools Menu → Programmer →
USBtinyISP​. Note: If you are using a
Windows PC, you will need to install a
driver for the programmer. For directions,
visit our hook-up guide at:
http://bit.ly/tinyAVRinstall
Typing in Your First Lines of Code
Carefully, copy this code into your Arduino window. Be very careful with spelling,
capitalization, and punctuation. All characters and punctuation marks are required for this
program to run. Any of the “grey colored” text that is preceded by ​//​can be ignored or left
out.
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3. Ok, now how do I connect that chip to my computer???
Ah… yes, we will need a programmer to do this. There are a few ways of programming the
ATTiny, but the easiest way is to use the ​Tiny AVR Programming Stick​. Remember that dot
on the chip?
Plug the ATTiny85 chip in so that the dot or
notch lines up with the notch on the stick. You
might need to adjust the legs of the chip so
that it fits.
Now, go ahead and plug it into your computer.
In Arduino, click on the ​Upload
button.
Watch the status messages at the bottom of
the window. It will indicate when it is Done uploading. If you copied the code incorrectly, you
might see error messages. Double-check the code. Remember that spelling, capitalization,
and punctuation must be exactly as it is in the example.
If the code uploads successfully, you should
now see a blinking LED on the corner of the Tiny
Programmer!
OK -- now, let’s look at adapting this and
making our own light patterns!
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4. Play with Code
Let’s take a more in depth look at the lines of code here. There are two functions that are
required in every Arduino sketch. These are ​voidsetup()​and ​voidloop()​. A function is a
way to group several instructions together. The instructions are grouped together using two
curly braces { }.
void​setup​()
{
pinMode​(​0​,​OUTPUT​);
}
This​first section of the code configures the chip​.​​Any
code that ​is​between the curly braces ​{​​}​after ​void
setup​()​will run exactly one time. The 5 controllable pins
on the ATTiny are all generic -- so, we have to configure
them as either an INPUT or OUTPUT.
voidloop()
{
digitalWrite(0,HIGH);
delay(500);
digitalWrite(0,LOW);
delay(500);
}
The ​voidloop()​function repeats over and over. After
the ​setup()​is run, the four lines of code here repeat
continuously. There are two commands / instructions
here:
digitalWrite(0,HIGH);​sets the voltage on pin 0 to a
HIGH state VCC. ​digitalWrite(0,LOW);​sets the
voltage on pin 0 to a LOW state or 0 Volts.
delay(500);​pauses the program for 500 milliseconds
before going to the next instruction. The ATTiny85
runs at 1 MHz (1 Million instructions per second -- or,
1 µs per instruction).
Challenge A
1) Flash!​Modify the code example so that the LED blinks at a rate of 100 times per
second. What do you see? Is the LED still blinking? Adjust the blink rate until you can
just barely see it blinking. What is time period for the blink?
2) Sweet Heart.​Now, adjust the sequence and timing of the on (HIGH) and off (LOW)
cycle to replicate a heart-beat pattern. (Hint: a heartbeat has two distinct beats).
3) Morse Code Challenge.​Morse code is a method
for transmitting text using a sequence of short (dot)
and long (dash) beeps, blips, or flashes. In the early
1830s, the electric telegraph system was invented.
Morse code was used to transmit text across long
distances.
Encode a short word, your name, or a message.
See if you can communicate a message across the room to another student. In
emergencies, the code SOS is internationally recognized as a distress signal. Hint: Be
sure to have a noticeable pause between letters and between words.
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