Hi, I'm using an attiny84 and I currently have one pin left for my project. I would like to use a servo, but I'm not quite sure what a servo requires. If I run the 84 on a 16MHz clock, would that be enough to generate a PPM?
In theory, yes. I don't know what pin you will be using; I do know the ATMega328 on the standard Uno is run at 16 MHz - but it uses a timer to gen the signals for the Servo library. You would need to generate the PPM "by hand" so to speak, but I am sure there are examples out there to follow.
Also - you would need to make sure the rest of your code is non-blocking (you probably already realize that), and that you'll have to keep it's execution within a certain limit of time, so as not to cause jitter in the PPM signal (which will cause the servo to "shake").
The ATtiny84 has 2 timers with 2 PWM channels each...Why not use one of those pins?
You may need to reconfigure one of you other pins, but that probably isn't a big issue. If it is then you need to tell us more about your project then you have so far. Is the servo lib to big to fit in remaining code space? Can you improve the efficiency of your code?
-fab