Our ATmega8 Dev Board

The avrbeginners ATmega8 board is a small and simple development platform just for the ATmega8 micro. We've done this to show you how a simple AVR circuit can look like and to show you that you don't really need an STK500. Before you can use this board you need a programmer. The web is full of schematics for easy to buid parallel port programmers and most of them work really well. Have a look at PonyProg (http://www.lancos.com/prog.html)if you want to build your own one. Of course, the mega8 board can also be connected to the STK500 via the 10-pin ISP header. You can then program the mega8 with the STK500 dialog in AVRStudio.

The first thing you should do after building this board is trying out some of the simple code examles you can find on this site (architecture section). When you verified that the hardware is OK, it's time to get rid of the external programmer (be it an STK or a parallel port one - it doesn't really matter) by uploading a bootloader. Code examples for them can be found on AVRFreaks.net or by googling.

This board offers some of the features the STK500 from Atmel has and, in some cases, code written for the STK500 can be used for our board without ANY changes. Most of the code examples on this site are written for or compatible with the mega8 board. The following pages describe each of the subcircuits (like the power supply, ISP, micro part, port headers and so on) and might give you ideas for your own designs.

Atmel has put together an app note on some design rules: AN042 (AVR Hardware Design Consideartions).

The subcircuit images are screenshots from the layout program (Proteus ISIS Lite) and contain garbage here and there. As I cannot put all circuits on one sheet (due to the limitations of the lite version), IC, Jumper, Resistor and so on numbers repeat.

As I can't make .pdfs I took screenshots of the layout and top silk so that you can copy it with your own layout editor:

Bottom Copper | Top Silk

It's no problem to build the board on perfboard though if you can't etch the PCB yourself.

Here's an overview of the board features with direct links to the subcuircuit descriptions:

Power Supply Circuit

mega8 / Reset / Crystal Circuits

ISP Circuit

Port Headers

RS232 Transceiver Circuit

LEDs and Buttons

Other Connectors And Jumpers