Speed measurement with opto coupler speed sensor

[NDi G.1]

Hi guys, I'm new to this community and inexperienced. 

I bought this sensor, an opto coupler speed sensor, and would like to use it with my stm card f446re to calculate the speed of a dc motor, but I have no idea how to calculate it.

Does anyone have any suggestions or idea?

Thanks ypu for the help.

https://abra-electronics.com/electromechanical/motors/encoders/sens-h206-h206-opto-coupler-speed-measuring-and-counting-sensor.html

[Vangelis Fortounas]

Hello

This sensor converts angular velocity to pulses. Freq of every pulse is proportional to the actual angular velocity.

So , the "rev per second" speed is the frequency of the output pulses divided by the number of apertures the disk has on it.

AN4776 (Timers cookbook) covers in detail the frequency metering. By searching internet "stm32 freq meter" , you will find a lot of resources how to do it.