Arduino Pro 328 Mini Review
This is the 5V/16MHz Arduino Pro Mini that I bought from Trossen Robotics. The first things that you will notice about this board is its simplistic design. The board itself is 0.7x1.3" (18x33mm) and according to Trossen's website it weighs less than two grams! I don't have a scale to verify that claim but I can tell you that is is probably quite accurate.
The Arduino Pro Mini comes without connectors of any sort but anyone serious enough to tinker with a little soldering can easily work around that. This board lacks a built in USB port and so you will also need a FTDI cable or FTDI Basic Breakout board. I recommend using the Breakout Board because it supports auto-reset. The FTDI cable lacks a DTR pin to connect to the Arduino Pro Mini and so you will not be able to use the auto-reset feature with the cable. You can also read my review of the FTDI Basic Breakout board here if you desire: http://salviusrobot.blogspot.com/2012/09/ftdi-basic-breakout-review.html
The reason that this board lacks a lot of features is so that it can be made as inexpensive as possible.
Trossen tells its users to select 'Arduino Duemilanove w/ 328' within the Arduino software when using this board. They also say to expect your delays to work twice as long (code will run half as fast as the Duemilanove at 16MHz).
ATmega328 running at 8MHz, Low-voltage board, USB connection off board, Supports auto-reset, 3.3V regulator Max 150mA output, Over current protected, Reverse polarity protected, DC input 3.3V up to 12V, On board Power and Status LEDs