CTCSS-Tones: A PIC12C508A CTCSS Encoder.
This is a little project to implement a CTCSS encoder on an 8 pin Microchip PIC12C508A or PIC12F508. It uses Pulse Width Modulation to generate a Sine wave output. The PWM pulse period is 243usec or 4115.226 Hz 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 for PIC12C508A is here.
The HEX code for PIC12C508A is here.
The source code for PIC12F508 is here.
The HEX code for PIC12F508 is here.
A description (in PDF) is here.