NTX2B arduino-interrupt

Interrupt Driven RTTY TX Demo, by Anthony Stirk M0UPU, October 2012, Version 5.

Transmits data via RTTY with an interupt driven subroutine.

Thanks and credits :
Evolved from Rob Harrison's RTTY Code.
Compare match register calculation by Phil Heron.
Thanks to : www.engblaze.com/microcontroller-tutorial-avr-and-arduino-timer-interrupts
RFM22B Code from James Coxon ukhas.org.uk/guides:rfm22b
Suggestion to use Frequency Shift Registers by Dave Akerman (Daveake)/Richard Cresswell (Navrac)

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 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.