I'm doing a project to scan a stroboscopic pattern onto 2 input lines. I then want to output a pulse on one of 2 output lines to signal the pattern turning left or right. Basically I want to pulse the "left" output pin if the pattern turns left and pulse the "right" pin if the pattern turns right. (This is a spinable dial)

I'm using some opto interruptors that I picked up second hand.

Has anyone does this before and have code available? Does anyone have advice on the best way to do this or am I on the right track?

Thanks in advance for any response!