Linux and electronics notes.

ATtiny45/85 or ATmega internally clocked at 8MHz to do temperature sensing fan control.
This demonstration uses an ATtiny85 programmed using the Arduino board and IDE to provide a PWM signal.

Configure your Arduino IDE and Arduino board as an in circuit programmer using this guide:
http://hlt.media.mit.edu/?p=1229

You'll need to change your preferred AT microcontroller to run internally at 8MHz.
You can do this in the Arduino IDE by selecting your board type in the Tools - Board menu.
For example, choosing ATtiny85 (internal 8MHz clock) and then from the tools menu again choose Burn Bootloader.

Continue reading for description and microcontroller source code.......