Some time ago I've published an article how to build a CTCSS encoder using an Arduino.
Now I've receive a question from Konstantinos, SV1ONW where the answer might interest other people too.
He wanted to use the CTCSS encoder in their local repeater, but for this only a single tone is required,
and to avoid the need to select the correct tone with the up/down push-buttons he asked me if it was
possible to have the encoder produce a single tone only.