I think this is the easiest development board that one ca build, but it servers it’s purpose so there is no need to make it more complicated. I needed such a design to test some code that I’ll be using to create a small unit to fit in my car. A unit that will be able to show me the Clock, outside and inside temeprature, Fuel status, RPM’s , and also control some other functions like making an anoying beep when i leave my headlights on.
I made the board using my photo etching technique, and as you can see the results are great. The dev board has 17 I/O lines that are connected to a 17 pin header. On the board there is a 2 color LED tied to PortC pin 1 and 2. On PortC pin 0 there is a PNP transistor that controls the output for a buzzer. So i always use pin 0 to connect the buzzer.
There is also an ISP connector on the board to be used for ISP programming, and an extra VCC pin so you can get power from it. I power my board with 2 AA batteries which provide enough current for testing purposes, but to ensure you’ve got enough power you should probably power it from 3 x AA batteries to get 4,5 V.
Here are a couple of source codes that i developed on this board:
This one makes a beep for 5 seconds than stops.
And this one blinks the two color LED.
I’ll be integrating these codes in a larger project. All codes are written in C and the board was designed in Eagle, here are the download links: