Using the Arduino Uno to program ATTINY84-20PU (Newark item # 68T3783). This Instructable shows how to use the Arduino platform to work with physically smaller processors, such as the ATtiny84 (84/44/24), ATtiny85 (85/45/25), and ATtiny2313. This example is specifically for the ATtiny84-20PU processor (Newark item # 68T3783) but can be adapted for the others boards by selecting the appropriate board from the Arduino software (i.e., Arduino IDE) and modifying the pinouts as required.
1) Ensure the Arduino software (aka Arduino Integrated Development Environment [IDE]) is NOT running on your computer.
2) Create new folder named "tiny" in your Arduino "hardware" folder
3) Download the Arduino-Tiny archive (ZIP-file)
4) Copy and paste the contents of the ZIP-file into the "tiny" folder.
5) Create a new file named "boards.txt" in the tiny directory using any text editor. Make sure to save as a text file (.txt).
6) Open the "boards.txt" file and the "Prospective Boards.txt" file using a text editor.
7) Copy board entries of interest from "Prospective Boards.txt" to "boards.txt". Or just simply copy the entire contents from "Prospective Boards.txt" to "boards.txt" like I did.
8) Save and close "boards.txt". Close "Prospective Boards.txt" (see picture for how the contents should look).