CTCSS-Tones: A PIC12C508A CTCSS Encoder.
This is a little project to implement a CTCSS encoder on an 8 pin Microchip PIC12C508A. It uses Pulse Width Modulation to generate a Sine wave output. The PWM pulse period is around 4KHz which is easier to filter out than odd order harmonics generated by a square wave generator.
The design is only a prototype at this stage, and further refinement may be required.
The source code is here.
The HEX code is here.
A description (in PDF) is here.
John.