I am finding both of them working but do not know which range is right.
Subsequently, is the middle 89 or 90?
If 0 is a defined position (say the 12 o'clock position) then the range will be 0 to 179 which is a total of 180 discrete points and position 0 is the same as position 180 (because we are dealing with a circle, rather than a line with separate ends)
The mid-point is 90 - which may seem a bit strange until you consider a clock face and simplify it down to only 4 discrete positions
Imaging the defined range is 0-3 with 0 defined as 12 o'clock The range is 0 to 3, position 4 is the same as position 0 and the midpoint is position 2
Totally confusing but I hope it helps
I am finding both of them working but do not know which range is right. Subsequently, is the middle 89 or 90?
The deg servo range is just a handy thing incorporated into the servo library, which actually maps the deg values used into us values. The actual operation of a standard servo may vary depending on how it is built and its quality. If you carefully examine a standard servo, it may actually mechanically rotate ~190 deg. The servo library has built in default minimum and maximum values, which probably can be changed if needed. Bottom line, splitting hairs between 89 and 90 deg positions is somewhat wasted effort. One has to evaluate each servo individually as to how it performs and what position it takes when sent a specific control value.