Having a couple of Bread Board Arduinos handy can really make prototyping quick and painless.  And while the Bread Board Arduino has pretty much been flogged to death in every way, shape and horse, we’re posting our rendition as reference for future projects and yet to be released libraries.  Before we begin, here are a few links to some of the nicer dead ponies previously referred to:

• The Arduino Reference Guide
• Beautiful Printout Template via Instructables
• An Incredibly Detailed Assembly Guide by NYU

For simplicity and to conserve power, our variant forgoes any and all voltage regulation.  It runs directly from 3x AA batteries where it will work reliably at 16MHz down to about 4 volts.  At 8MHz the battery voltage can safely fall to as low as 2.5 volts which is a great use for  “dead” batteries.  As indicated by the label, this specific Mega328 has it’s fuses set to the internal RC oscillator at 8MHz, the 16Mhz crystal is on the board but it’s just for show, what a poser…

The status LED is on Arduino pin 13, there is an SPI/ICSP connector at the top right and the USB dongle in the middle.  As we’ve been working on a modified bootloader, the ICSP connector has been seeing much use.  The USB miniboard is an in house design, it’s based on the QFN package of the FT232R and as well as having all the I/O broken out, it sports a 3/5 volt slide switch on the bottom.  The remainder of the parts are a smattering of capacitors, both bulk and bypass, as well as the reset and power switch.  Below we have the circuit diagram, roughly laid out in the bread board fashion, click to view full size:

The Eagle footprint for the Mega328 is arranged as per the physical chip pins.  The library file is available here: n0m1.com-mega328p.rar.  And the schematic in eagle format is here: BBA sch