Hi Ananth,
In your case there is no need of an ADC, you can simply connect it to any of the digital pins of the microcontroller. All you need is to check the whether the output is there or not.
Hi Vignesh,
In your case you need an ADC between the optocoupler and microcontroller, since as far as I understand you have to read the value of the voltage at the output of the optocoupler to control the TRIAC accordingly.