Hardware to measure velocity via string/wire attatchment? beginner This is a broad question but I want advice on what type of hardware I should look for to make a device that could measure the velocity of an object attached via a string/wire to some sort of rotary wheel.

The purpose of this is to attach it to a barbell and measure mean-velocity for weightlifting atheletes.

I'm a software engineer by trade but know nothing about hardware. I will obviously need to start with simple projects to learn, but I would like to know which hardware I should lean towards buying, so I don't have to re-buy anything?
This is an example of the optical encoder.
You want to use interrupt detection, rather than polling.
Or maybe even an HW counter.
That's all you really need.

I am using 4 of them for a car.

I am in the process of refactoring the code, but you could already have a look at the driver &amp; example I wrote for ChibiOS, here.