YACK - Yet another CW Keyer

The more I listen to soldersmoke, the more I am motivated to build a transceiver from scratch (especially as the DC receiver I built earlier works so well!). That would of course require a standalone keyer chip. Some are available from commercial vendors, some are based on PICs, some on AVRs but few have well structured and documented source code.


So I have developed a flexible CW library for the AVR embedded controllers which can be easily modified and deployed in different applications. As a sample application for the library I have written a keyer with all the bells and whistles (memory, pitch and speed controls, beacon mode, callsign training mode, sidetone and much more)

Want to make your own CW keyer? Here you go. Do you need a trainer that can decode the output of a CW paddle and display it on a LCD display? Easy. Do you want to create a beacon keyer for ARDF? No problem! Do you need the chip for other functions (like controlling the VFO)? The library can be integrated into other code.

To encourage other HAMs to contribute their code to the project I have released it as open source on Sourceforge. A binary version for the ATTINY45 controller is published there as well.

Once the AVR chip is programmed, it can be used in a minimal configuration as detailed in the above picture (click on it!) In a RF sensitive environment the power supply and the keyer lines should have blocking capacitors towards ground (10-100nF).

The TX keyer output (Pin 5) can deliver either a positive or negative logic 5V signal (programmable at run time) that can source/sink 20mA according to chip specifications. The signal should be used to drive the TRX keyer circuitry as required. A NPN transistor is shown as an example in the schematic.

Where to find the code

The Sourceforge homepage from which the source code and binaries can be downloaded can be found here

The project is documented using doxygen. The web based documentation can be accessed here.

Note that you can access the source code documentation too (in the "files"-section of the above link).