Help building a counting circuit with circuit using LM311

[mif987]

Hi, I'm building a circuit that uses an Infrared LED that sends a signal to a receiver. I want that , when the wave is interrupted, it will generate a signal that will be sent to a CPLD that will do a count. Basically, every time the LED is interrupted the CPLD will do a count. The issue is that I've been told that since the LEd works with analog signals the CPLD won't detect the "low" but it does detect the "high" so I used a LM311 to fix the issue but it isn't working. We put a reference voltage in the inverting pin, the Led detector output in the non inverting pin but the output isn't as it should be.

Any help?

 

[MikeMl]

Circuit diagram?

 

[mif987]

I'll post it asap.