Using a Quadrature Encoder with an ATtiny 2313 and an OLED Display

In this instructable you'll learn how to use a rotary encoder (see http://en.wikipedia.org/wiki/Rotary_encoder ) with a microcontroller and how to display the numeric value as a bar and a numeric value on an OLED display. See the video below for the project in action. The right upper corner of the OLED display shows a small clock, too.

In the image you can see the ATiny2313 in a SMD package, which I've soldered on a PCB with headers, but the microcontroller is available in easier to use DIP packages, too.
 

Step 1 Hardware

You'll need the following hardware:

* ATiny 2313
 * 18.432 MHz oscillator (this frequency is required for a perfect 115,200 baud signal for the OLED display, but the display has auto baud detection, so you can use other oscillators as well, or just the internal oscillator)
* 7805 voltage regulator
* 10 µF electrolytic capacitor
* 1 µF ceramic capacitor
* 2 x 100 nF ceramic capacitor
* 3 x 10 k resistors
*  µOLED-128-G1 (from http://www.4dsystems.com.au , but you can use a LCD display, too, or something different, e.g. use the encoder for controlling the pitch of some sound output) 
* quadrature rotary encoder (I've used Alps, type EC12E2420404, but you can use other encoders)
* ATiny programmer (I've used the AVR Dragon: http://www.atmel.com/dyn/products/tools_card.asp?tool_id=3891 )
* a breadboard like you can see in the video, or veroboard and some wires, if you want to solder it
* some tools, like solder iron, if you use a veroboard, side cutter etc.
* power supply (anything from 7 V to 12 V works, even a 9 V battery)
* a PC with Windows for WinAVR and AVR Studio

The schematic is very easy to build this on a breadboard: