Quote

2) The LED starts out at max speed

unsigned long currInterval = myEnc.read() / 4;



if(currInterval != prevInterval)

{



That's a silly statement, since an LED doesn't have a speed. It is on or off.Using three variables, all with period in the name, that contain values that differ by a factor of 4, to keep track of the current and previous values is one too many.I really do not see the benefit of comparing the current interval to the previous interval. I can't imagine that it is NECESSARY to keep the LED on or off until the LED has completed the interval that it was turned on, or off, for, when the interval changes.If you wish to toggle the state of the LED pin at a "flashes per minute" rate, you need to decide what the encoder reading means, and calculate the on/off time based on that meaning.Then, independent of reading the encoder/calculating an interval, you toggle, or not, the LED pin.