Single Joystick axis Position Measurement with PWM contant frequency 555 Timer

A 555 Timer circuit used to generate a PWM signal with Constant Frequency. The Duty Cycle (Ton or Toff) time can be used to determine the position of potentiometer (Joystick axis). Making use of interupts on the Arduino the axis position can be monitored with a single IO pin. Using PWM reduces noise compared to a direct voltage measurement on the potentiometer (using a Wheatstone Bridge and a Differential Amplifier). It also uses less power in comparison, when a CMOS type 555 Timer is used. R1, R2 and R3 simulate the single Joystick axis. R4 is just a current limitor. C1 can be used to adjust the PWM frequency. C2 is just a decoupler capacitor. D1 and D2 are simple signal diodes, but could be replaced with basic LEDs.