The PWM sketch works to vary the output linearly, however, the light outputted by the LED does not change in a linear manner. When applying the scientific metric of ‘perceived brightness versus time’ ...

So we can use a simple formula for routine calculations: “level = 255/5 x effective voltage” The experimental code for ATtiny85 is the same as the Arduino Sketch, as indicated. The only deviation is ...

A few months ago, [Julian Ilett] found a problem using the Arduino library for PWM. Recently, he revisited the issue and used his own PWM code to fix the problem. You can watch the video below.

If you've got an Arduino of any variety, you might have noticed some of the pins on the board have a tilde mark or PWM printed next to them. What is PWM?

Official Arduino Example Tutorials: The Arduino computer software is loaded with tons of examples for you to use in your own code or to run through as a learning experience.