One of the more popular items on my website here are the Arduino based CTCSS projects
One disadvantage of these projects is that a traditional ATMega328p microcontroler is rather big and in the way it is used in the projects needs a 16MHz x-tal to function. This results in a circuit that is often to big and also a more expensive solutions that one would hope for. For these reasons I've created a new version of this project based on the popular "ATTiny" microcontrollers.
Some of the advantages of these ATtiny microcontrolers is that, not only can they be programmed using the same arduino IDE and Arduino style C++ code,
they can also be flashed using a regular Arduino Uno or Arduino Nano as "ISP".
On top of that these small microcontrollers have an internal oscillator of 8MHz and do not need a x-tal to work.
( Admitted that this is also possible with the ATMega328p but the procedure to do so is not as straight forward for unexperienced users )
This reduces the number of components needed to make a working Tone encoder.
One disadvantage is that this internal oscillator is not very accurate, so one might need a 'try-and-error' approach to hit the target ctcss frequencies...
But once this barrier is crossed it works just fine !!
Check out the full project here: