I'm working on learning Morse code, and I'm looking for a way to use my computer as a practice oscillator with a double paddle key.
I'm using a Linux PC, but a Raspberry Pi solution would be cool to. I do have a USB Serial adapter.
This page appears to be what you're looking for. This technique uses the Linux LV2 plugin. You'll have to build an interface with a 555 timer chip.
SETUP: an UltraPico Keyer, keys a 555 TIMER CHIP..from the audio output of the 555, an audio cable is attached and goes to the input of a laptop's mic jack input...the 555 time chip sidetone is very rough sounding with lots of high pitched harmonics and key clicks...INSTEAD of trying to filter the 555's raspy tone, this video demo's using TRIGGER MIDI MONO to recreate the original 555 sidetone cw element and then a LINUX LV2 PLUGIN called TRIGGER MIDI MONO keys another CPO, a software code practice oscillator synthesizer called SIMPLE SINE GENERATOR(lv2 plugin)...this SIMPLE SINE GENERATOR has zero rise or fall time and therefore has loud key clicks...so those need to be filtered out....by another LINUX LV2 PLUGIN called CALF FILTER...calf filter does a great job of taking out all the harmonics and key clicks and produces a nicely shaped cw element audio waveform output
Previously, this CW REGENERATION technique was accomplished using WINDOWS VST PLUGINS, or a non free app called LINUX NATIVE REAPER. After discovering this TRIGGER MIDI MONO plugin for LINUX, this CW REGENERATION technique can now be utilized with ALL FREE LINUX APPS ...
NOTE: familiarity with KXstudio, and his LINUX JACK AUDIO APPS for Linux is necessary in order to understand fully, the method that is being demo'd...there are more videos in this QRQcw youtube channel to learn more about JACK AUDIO for LINUX/windows/mac and the Raspberry Pi....
NOTE: MIDI DATA MESSAGES, of NOTE ON and NOTE OFF are used to instruct (key) the software code practice sine wave oscillator APP called SIMPLE SINE GENERATOR. (there are other LINUX audio plugins that would also work like AMsynth) -https://github.com/amsynth/amsynth
MIDI DATA MESSAGES - WHAT IS MIDI ? http://www.instructables.com/id/What-is-MIDI/
Here is a solution that has been tested and works on Ubuntu 14.04 LTS.
The paddles connect via a standard FTDI-based USB-A Male to DB9-Male Adapter cable.
(Note that this shows how the Paddles are wired to a DB9-F which plugs into the DB9-M on the Serial-to-USB Adapter cable)
For reference, the traditional pin assignments for DB-9 serial is shown here.
This video demonstrates a method to hook up your cw paddles, key and bug to your Linux computer.
Dahdidah is the application chosen to perform the software cw keyer functions.
A USB TO SERIAL PORT ADAPTER is used to interface the morse code instruments directly to the serial port pins to "key" Dahdidah.
Jack Audio is the Linux sound engine used, with KXSTUDIO's CARLA and CADENCE.
Dahdidah uses the serial port to "key" its CODE PRACTICE OSCILLATOR sound system.
Dahdidah will use the WINEASIO - ASIO DRIVER - for the best audio production with near zero latency.
HERE IS A LIST OF THE BASIC STEPS.
DOWNLOAD the DEB FILE to get the KXSTUDIO REPOS
DOWNLOAD KXstudio's CADENCE
DOWNLOAD KXstudio's CARLA-GIT et al,
DOWNLOAD KXstudio's META-WINE package
DOWNLOAD KXsutdio's WINEASIO
important: REGISTER WINEASIO
get your USB TO SERIAL PORT adapter working and ready to go on boot up
link your new ttyUSB0 SERIAL PORT ADAPTER to WINE
DAHDIDAH PDF MANUAL: http://qsonet.com/doc/dahdidah.pdf
AUDIO DERIVED CW KEYING CIRCUIT to key your rig