In post #5, in the first picture, I see one photodiode connected to an opamp but I cannot see where the output of the opamp is going.
Another sensor, just below, marked humidity/ temp sensor, is connected with one port of the microprocessor directly. The rest of the connections are for power, ground etc. etc. etc.
So are the most of the connections seen in the microprocessor.
If you want to interface YOUR microcontroller with something, you need to study the nature of input and output and the communication protocol. There is nothing more than that...