[GreenKeys] Model 15 to a computer

[Joe Duszyński]

My decoder recently died so have been toying with replacements ideas that
would also incorporate some sort of serial interface to the computer

The least soldering and building or thinking too hard.....
An old computer with built in serial interface is probably the easiest
thing using optocouplers and say heavy metal as your (go between)
Its pretty easy to find an old computer with built in serial. To tell if
its suitable run heavy metal on it with a loopback to pins 2&3 on the
serial port at 45.5 baud
If that computer sends what it receives then "Nagle's" board at
https://www.aetherltd.com/connecting.html would be your magic device
interface.
All the parts for that board are available.

Arduino...
Lots of solder, cerebral usage, wires laying all over the place
and programing......................
I started playing with arduino's recently because as I stated my decoder
died and I wanted something a tad more sophisticated to do the decoding and
to have some sort of serial interface too would be nice to send to the
teletype from computer all in one box instead of two boxes I had. My prev
decoder ran the teletype and would put the text on a video monitor and it
was about 30 years old. I also had on the loop a serial interface and would
sometimes get a mess if both talked at the same time.
On the arduino front I have the Sending from the arduino down pat. Decoding
from the loop I just got working. Now I need to add a second "loop decoder"
and feed demodulated RTTY input into the second loop decoder is the project
for this weekend...
For that project I heavily borrowed source code and circuits from two
sources and modified it for my needs.
https://k183.bake-neko.net/ji3bnb/page13_d.html.. (PLL CIRCUIT and some
code)
and
https://heepy.net/index.php/USB-teletype  (Some of the code)
The volpe board kinda would do what I want BUT I'm also not into soldering
SMD's (Surface mounted devices) so since it was designed for a "32u4 AVR"
I decided to adapt the code to run on a "Leonardo/Arduino board" and add a
second decode input for the RTTY.
Nice thing about having two decode loops (one for the keyboard/teletype
loop) and one for the RTTY the arduino can monitor the traffic and either
block the keyboard or block the RTTY when one or the other is sending at
least thats the plan. And its a hell of a lot easier than all that SMD
nonsense.
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