circuit explanation (IR sensor)

In this DICM circuit, IR sensor is used to detect the obstacle in front of this DICM system and detect the crops. Picture below shown the IR sensor connection in DICM circuit. 

and the PCB connection, 

Referring to the picture above, the IR sensor was connected to the analog input 0 and analog input 1 (pin 23 and pin 24). The input of these IR sensor is analog input. It means that the IR sensor will detect the obstacle and crops in a small range. For example if the IR sensor detect the obstacle in front of DICM system, the signal will be sent to the micro controller to process the signal. The output signal of this IR sensor is digital signal which is 1 (5V) and buzzer will be turning on that was controlled by TIP 120 and the DC gear motor will be turn off. The buzzer will still remains turning on until there are no obstacle in front of this DICM system. The same thing also happen if the another IR sensor detect the crops. If the IR sensor detect the crops, the DC gear motor will be turning off and the solenoid motor and sprinkler motor will be turning on.