[aprssig] APRS / Packet board for Arduino

[Jason KG4WSV]

The Arduino is a serial bootloader enabled AVR (ATmega8/168 family)
microcontroller board.  The high points:

- lots of microcontroller stuff is all wrapped up, so you can program
in pretty high level C on a microcontroller.  it's designed for
non-technical types (e.g. artists), but this lazy technical type
appreciates the wrapper. (:

- serial bootloader and built-in USB/RS232 hardware, so no external
programmer required

- IDE is free and cross platform (linux, os x, windoze)

- if you get tired of the Arduino wrapper, peel it back and use the
avr-gcc toolchain, still free

- several variants and peripherals.  Plug-in daughterboards are called
shields and can be stackable.  varieties include protoboard, motor
controller, ethernet, etc.


I've used the base system to build several balloon experiments, and
have flown the software running on custom hardware several times.  I'm
currently designing a couple of shields to use actual arduino CPU
boards (instead of custom PCBs) to make a modular hardware library for
putting together balloon experiments.

-Jason
kg4wsv