PIC18 Microcontroller simulator
Scheme of the ADC

The ADC display is connected to the D port of the micro-controller, which is the only port represented on the scheme below.
Without entering into details, we can notice that the communication between the micro-controller and the display is operated by mean of a 7-wires bus.
This bus contains 4 data lines (D7,D6,D5,D4) and 3 control lines (E, RS, R/W).
A potentiometer allows to adjust the contrast of the display.