ALTERA MAX 10 How to write custom ADC interface verilog code

You don't say which MAX 10 development board you are using. Is it this one: https://www.altera.com/products/boards_and_kits/dev-kits/altera/max-10-fpga-development-kit.html ?

The MAX 10 part on this board has an integrated ADC, it is not a separate part. The above page has pointers to the full board level schematic.

If so, have you looked here and read these documents: https://www.altera.com/documentation/sam1393576011848.html ?

PS If you are going to ask questions, you need to be REALLY specific about what boards/chips/software/etc you are using. We are not mind readers.