This is a implementation of the HP RedEye infrared protocol used
on HP 82240A printers as used for printing from their great graphing
calculators.

This implementation currently works on a Arduino Duemilanove prototyping
board which has a AVR ATMega328P running at 16 MHz and connected via
a integrated USB to serial bridge (ft232), but you can easily port it to
any other AVR with the two standard 8- and 16-bit timers.

AVR Resources:

    This code uses Timer/Counter 0 in Fast-PWM-Mode to create
    the 32kHz IR carrier, the IR-LED is connected to OC0B/PD5.

    Timer/Counter 1 runs at about a 7th the rate and does the
    bit-timing, turning off T/C0 (and hence the LED) as needed by the
    protocol.

    In principle, you could still use T/C1 for PWM, T/C2 is not
    used at all.

To use this code as is:

Connect a IR LED with the anode connected to arduino digital output 6
and the cathode connected to ground, with a 100 Ohm resistor or so
in series.

The actual implmenentation is in avr-redeye.h and .c, there are
only two relevant functions:

     avr_redeye_init() sets up the timers

     avr_redeye_put(c) puts a character "c" in the buffer to be sent
     to the printer

There's a little demo script test_redeye.py (written in python, using
the pyserial module to access the serial port) as a short example.

Read the included .pdf for the exact specification from HP.


LICENSE:

	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.

	https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html