3v3 8mhz Support

[Noah517]

I'd like to say first of all how amazing LibAPRS is and how helpful it has been.

After experimenting with the library I decided to use it for an upcoming HAB tracker project. Due to the number of sensors and components that I want to include, I decided to use an ATMEGA2560. I found a port of LibAPRS that just redefines the pins for 2560 support. The rest of the library works the same. It works perfectly and I can send APRS location data plus telemetry data. I was wanting to use the lesser-known ATMEGA2560V so I can run the system in spec at 3.3v 8mhz. I was wanting to do because many of the sensors are only 3.3v tolerant and it would be much simpler to bring the whole system down to 3.3v instead of using logic level shifters. As I don't have ATMEGA2560V on hand at the moment, I reflashed the bootloader of my Arduino Mega to run on the internal 8mhz clock at 5v. I didn't change anything in the LibAPRS library when I did this. After re-programming the mega with my APRS sketch it still seemed to work. But I noticed that the comment portion of the APRS packet was only transmitting the first 4 characters, nothing else. I don't know if this is an issue with the accuracy of the internal 8mhz clock of the ATMEGA2560 or an issue with the library. Also, when running at the normal 16mhz, sometimes the second half of the comment would not send. It didn't happen very regularly so I didn't think it was an issue but I wanted to put it out there if it had anything to do with it. It would be extremely helpful if I could get this whole system to work at 8mhz so I can run it at 3.3v.

Noah