k3ng_rotator_controller/libraries/P13

                   _   		The Arduino n' Gameduino
 __ _ _ _  __ _ __| |_ 			Satellite Tracker
/ _` | ' \/ _` (_-<  _|
\__,_|_||_\__, /__/\__|		Written by Mark VandeWettering, K6HX, 2011
          |___/        		brainwagon@gmail.com


Angst is an application that I wrote for the Arduino and Gameduino. It
is being distributed under the so-called "2-class BSD License", which I
think grants potential users the greatest possible freedom to integrate
this code into their own projects. I would, however, consider it a great
courtesy if you could email me and tell me about your project and how
this code was used, just for my own continued personal gratification.

Angst includes P13, a port of the Plan 13 algorithm, originally written
by James Miller, G3RUH and documented here:

	http://www.amsat.org/amsat/articles/g3ruh/111.html

Other implementations exist, even for embedded platforms, such as
the qrpTracker library of Bruce Robertson, VE9QRP and G6LVB's PIC
implementation that is part of his embedded satellite tracker. My own
code was ported from a quick and dirty Python implementation of my own,
and retains a bit of the object orientation that I imposed in that code.

While the P13 library is reasonably independent and can be used in
other applications, the remainder of the code is fairly specific to the
particular hardware I had on hand:

1. The Gameduino

        James Bowman developed the Gameduino as an Arduino shield to
        generate sound and graphics which might have been typical of
        8 bit computers of the 1980s. It consists of a Xilinx FPGA,
        programmed with a version of his J1 Forth processor, and
        generates video and sound. It is programmed from the Arduino
        using a simple set of commands sent over the I2C bus.

	You can find more information here:

		http://excamera.com/sphinx/gameduino/

2. A DS1307 RTC

        Sparkfun has a Dallas Semiconductor DS1307 chip mounted on a
        handly little breakout board.  I used this chip to keep track
        of time.  It's not particularly great: it drifts by a couple
        of minutes a week in my prototype: a better and more accurate
        timepiece would enhance the usability of this prototype.  I've
        considered using a GPS to keep track of time, that extension is
        left as an exercise for the motivated reader.

3. An AT24C1024 Serial EEPROM
	
        The ATMEGA328 used in the Arduino contains a mere 512 bytes of
        EEPROM.  This is enough space to store a few satellites, but I
        wanted to have greater capacitity.  So, I got some 128K byte
        EEPROMS for about $4 from digikey.  Each one of these can store
        the data for about 750 satellites.  My prototype just uses one,
        but it's possible to chain up to four of them together.

4. A Rotary Encoder

	The entire interface is driven from a single rotary encoder w/
	a built in switch, similar to this one:

		http://www.sparkfun.com/products/9117	

	The code turns on the necessary internal pullup resistors to 
	allow it to be directly wired to the Arduino input pins.

	Currently the encoder is read in the polling main event loop.
	This means that quick motion of the encoder is not adequately
	tracked: consider this another exercise for the motivated 
	reader.


I hope you enjoy the code, and find it useful and/or informative!

Copyright 2011, Mark VandeWettering. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

   1. Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.

   2. Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer 
      in the documentation and/or other materials provided with the 
      distribution.

THIS SOFTWARE IS PROVIDED BY MARK VANDEWETTERING ''AS IS'' AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> OR
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are those of the authors and should not be interpreted as representing
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