Question Attach the hall-effect 'potentiometer' on the motor shaft on Arduino SMC3

I am thinking to put the sensor on the motor shaft (Instead of on the gearhead shaft).
Since I am using a 1:50 gear head and designing for a total maximum 90-degree motion angle of output/horn, my calculation for a Quarter rotation output of my motor would turn a total of 12.5 turns.
So, I am thinking of getting 20 turn-hall effect potentiometers and attaching them to the motor shaft (it is a dual shaft motor, the front one attached to the gear head).

My goal is to get the most precise output/horn without adding another gear up for the standard (single turn) potentiometer.

Does this sound a good idea?
Any suggestion which 20 turn-hall effect potentiometer I could try?

I suppose you missed my notes. I use a gearhead, and I am not planning to attach the sensor to the gearhead but to the motor shaft. This means the motor shaft will turn multiplier turns, 12.5x per my note.

It is just like a typical servo motor system to get the most precision as they have a rotary encoder on the motor shaft, not the gearhead output shaft.

I suppose, in terms of simplicity, attaching the 'potentiometer' to the gearhead's shaft (typically built) and to the motor's shaft should be the same.

Question #1: can you write your own arduino code that will handle the multi-turn potentiometer ?
If not then you can't use such a solution because SMC3 only supports single-turn potentiometers/hall sensors up to 270 deg. of measurement.

Question No. 2: why are you concerned about the accuracy of the measurement , the backlash of the gearbox in any rotary slinky is much larger than the possible measurement error of the sensor attached to the axis of the gearbox.

#1 no need to rewrote the code. I just need a multi-turn "potentiometer" directly to the (rear) shaft of the motor.
#2 I use a harmonic drive gearhead, which has a super small backlash. The issue I have now, the return position from multiple movements (either on Clockwise and Counter-Clockwise) was not precise enough. Perhaps off about 5 degree angles, when I have the "potentiometer" attached directly to the gearhead shaft (the horn). Tried on a regular 10K pot and 5V hall effect 360'.

Ok, I have read the information about multi-turn potentiometers actually should work with standard arduino code.
What are you building ? , so far no one was looking for that much precision measurement when building a motion sim.

I am building 6dof Steward with rotational actuators.

"so far no one was looking for that much precision measurement when building a motion sim."
Well, I guess you just found one is looking

Ok, you made me curious what power of motors are you planning ?, how much such a motor with gearbox costs if it's not a secret ?
Platform more for driving or flying ?
In principle, a multi-turn potentiometer should work, provided you choose so that the movement of the lever is adequately reproduced by the number of turns of the potentiometer.
Have you done tests with a Hall sensor ? such a
https://www.ebay.co.uk/itm/P3022-V1...1YX&toolid=10001&customid=&ufes_redirect=true
if so, what was the measurement error ?

Yeah... I tested that green boy as well. I also try the black housing from digikey (that usually higher quality source).

I am currently planning to race, for now

The harmonic gearbox is about $300-ish, landing in Boston (US).
I use this DC motor, good enough efficiency https://amzn.to/3CJKuEX

I documenting (photos and videos) here: https://www.instagram.com/stories/highlights/17943343157808731/

Wow, I looked at the instagram, beautiful project
Perfect execution of the parts

power supply protection

https://www.tvdr.de/sim/2/power.htm