This instructable will inform you how to run any atmegaxx8 series chip on its own.
Atmegaxx8 (doesnt matter which one but i prefer the 328)
Breadboard (circuit on bottom left is irrelevant)
LED and resistor (optional)
Step 1: Breadboard
I have included a resistor on pin 14 or digital pin 8, purely to test my chip.
Step 2: Computer Setup
Download the bootloader files from here.
Go to wherever your arduino sketchbook is and create a new subfolder titled 'hardware'.
Extract the downloaded file Breadboard.zip into the new hardware folder you created.
Restart/start you arduino programming environment and you should see in tools-boards a new entry called arduino on breadboard
Step 3: Computer-Arduino Setup
Under boards select the new arduino on breadboard entry.
Under programmers set it to arduino as isp
Under examples you will find an example called 'arduino isp' upload to your board.
Under tools click burn bootloader, this can take a few minutes so dont think its not working.
When this is all complete, you should have a chip that can function like a normal arduino but without the clock.
Step 4: Uploading Sketches
The Arduino way is detailed in the image.
The USB way is to connect TX to RX and RX to TX between the chip and your breakout board and just upload from there.
This is where you may want and LED, just to test its working.
I also like to print out a sticker for the chip so i know which pins are which, if the one below doesn't work inbox me and ill fix it.