Programmable CW Morse Keyer / beacon


Marko Pavlin has designed a Mini USB dongle with STM32F0xx , he writes:

Mini USB dongle with STM32F0xx is suitable many for simple, mini projects. I attached speaker to Timer14 PWM output (Pin PA6) and LED (or optocoupler connected to PTT) to GPIO pin PA0
The provided software is based on USB Virtual Com Port (VCP) device. The setup is done with command line interface using terminal from any PC. The setup is stored in the internal flash and PC is not required for normal operation. The mini beacon keyer can be used when powered with 5V.

Project info at Mare & Gal Electronics.

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  1. I would connect the speaker in pull-down fashion instead. A closely-related STM32 data sheet says 8mA sourcing, but this board runs at 3.3V, so it would be a bit louder if the 20mA sinking capability is used.

  2. Hi!

    Thank you for your comment. It’s just for reference to show which pin is audio output. It is usually connected via transformer to the ham rig or to some audio amplifier via capacitor.

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