Month: December 2012

My two girls and I are making personalized home-made “Arduino Blinkies” this year.  We’re making the “64 pixels” display that is written up here:

http://tinkerlog.com/howto/64pixels/

This project only requires three components:

• An Atmel ATTiny2313 micro controller
• An 8×8 LED grid
• A two AA battery holde and two batteries

Up to now, all of my Arduino experience has been playing with a Duemilanove with the Atmel ATMega328 in the socket.  I have seen descriptions of how to use the chip “bare”, but at $3-$5 I didn’t really feel like experimenting with them that much.  (Plus if I did use one in a project, I would have to flash the bootloader onto it’s replacement and I haven’t tackled that yet, either.)

While poking around on the Internet looking for a fun project to introduce my girls to the other side of computers and how they work, I came across the 64pixels project, and that introduced me to the ATTiny2313.  This chip (also by Atmel) is on the small end of their line of compatible chips, and costs a whopping $0.95 per chip!  The entire cost of the 64pixels project is below $5 each, so I can afford to let the girls experiment a bit and not break the bank.

So, the first thing I had to do was determine how to program the ATTiny chips on my Duemilanove.  The pins on the ATTiny aren’t the same as the ATMega so I can’t just plug it in.  Terms such as ISP (In-System Programming) and JTAG (Joint Test Action Group) were tossed around and friends on my mailing lists offered to loan me theirs – but that was like loaning a pair of snow skis to a Texan.   I didn’t know how to use it, or if I even really did.

Thankfully a few nights of searching the Internet found people had documented bits and pieces of it.  Through a lot of reading and trial-and-error, I’ve put together my notes on how to flash a common Arduino Processing-based program onto any Atmel AVR-based chip.

int pin = 8;
int value = HIGH;

// the setup routine runs once when you press reset:
void setup() {                
  // initialize the digital pin as an output.
  pinMode(pin, OUTPUT);     
}

// the loop routine runs over and over again forever:
void loop() {
    digitalWrite(pin, value);
    if (value == HIGH) {
      value = LOW;
    } else {
      value = HIGH;
    }
    delay(20);
}

// Define the pin to test for analog features
int anapin = 13;
// Define a digital pin to flash each time the 0..255 analog cycle has completed.
int digipin = 2;
int value = 0;

// the setup routine runs once when you press reset:
void setup() {                

  // initialize the digital pin as an output.
  pinMode(anapin, OUTPUT);     
  pinMode(digipin, OUTPUT);
}

// the loop routine runs over and over again forever:
void loop() {
    analogWrite(anapin, value);
    value += 2;
    digitalWrite(digipin, LOW);
    if (value >= 255) {
      value = 0;
      digitalWrite(digipin, HIGH);
      delay(5);
    }
    delay(1);
}