/* This program written by Alastair GW0AJU.
The code presented here for an all HF tri-band digital vfo.
The program code is set in this listing as the middle ham band 30m, 20m, and the 17m band,
with either CW or USB.
In all cases, the code uses a 9MHz intermediate frequency for reception, and also for SSB exciter. However
for CW transmissions, the digital VFO is placed directly onto the dial frequency as the digital vfo is used as
the carrier oscillator for TX mode, thus CW keying the digital vfo for CW tx onto the output dial frequency setting,
then the digital vfo adjusted for reception onto a 9MHz intermediate frequency setting.
An i/o bus expander of the pcf8754 type is used to access to an output LED panel indicator, while also giving
a logic output for ham band antenna switching on three of the i/o bus pins, P0, P1 and P2. The carrier mode
switching is also present on the i/o bus, on pins P3 for CW and P4 for SSB, used also for switching between
CW and SSB Tx/Rx circuits such as the BFO frequency selection for CW and SSB and band pass filtering. The morse
key and PTT line is also imaged on i/o pin P5.
It is suggested that in order to accurately use the twi display and i/o bus expander, use a twi searching program
to find the network address of each unit.
Ardunio board used = Ardiuno Uno
original date 8th Feb 2016
The code is in a text format and should open up in notepad. Cut and paste from notepad into the Arduino ide.
https://docs.google.com/document/d/1q89-y7S64LwkzCP7Mpg6COuq4jrISw6oIQ8Z6vkekoQ/edit?usp=sharing