I have seen plenty of Instructables showing how to work with microprocessors, but they all assume that you have worked with them before and know what you are doing. I have not seen an Instructable that takes you from nothing and builds on each step.
What we will do here is to start with a bare breadboard and build each connection and each component until we have everything we need to program a microcontroller to do something. In this Instructable we will blink some LEDs in sequence... then if you build this circuit... your first project can be to change the code slightly to make it into a traffic light.
I picked an older Atmel chip, the Tiny-26 to get started. It is a smaller microprocessor, very inexpensive, and easy to understand. Once you understand what we are doing here, you may want to try a more powerful chip like the Mega-328P which has more pins and more memory.
Note: The Tiny-261, Tiny-461, and Tiny-861 are pin compatible newer versions of the Tiny-26. They have 2K, 4K, and 8K of memory. If used, simply change the header by selecting the appropriate chip and recompile the program to use the newer version. The new chips have more functions that can be assigned to each pin. See the datasheets for more details.
Tiny 261, 461, 861 Datasheet (PDF)
Tiny 26 Datasheet (PDF)
Below is an image with the pins for the chip we will be using... we will be connecting the power and ground... in this case 5v. So where do we get 5 volts? We will build a power supply from a 9v battery.
Let's get started!
Video posted in a larger size at: http://www.youtube.com/watch?v=Jxica6Yenh8