Hi, so I'm currently doing a project to count the length of a string. The project consists of using magnets embedded into a spool with a hall effect sensor in proximity to it that counts pulses as a motor turns the spool. As the string gets wrapped around the spool, knowing how many magnets there are in one rotation gives you the premise to work off calculating the length from there from the number of pulses. The Hall effect sensor is attached to a pcb with the output of the hall effect sensor connected to a MSP430 microcontroller that is coded to count the pulses. However a problem arises when it comes to how to tell the system to stop counting. We have a laser sensor and a receiver but this could be rife with problems. What would be the best way to tell the system to stop counting once the string is fully wrapped around the string?