I have an application for persistence of vision graphics on a spinning platform. I have no experience with this. Also this wheel is spun up and left to spin down, it is not sustained speed. Does anyone have experience with this topic? I am using a 16F1827 MCU and 5 LEDS arranged linearly. Is there a way to determine RPM without using hall/reed switch and magnets?

Any help or info would be appreciated.

Nick