In order to save pins the designers of the PIC16F1937 processor made the connections to PORTA dual purpose. These pins can be used as digital inputs or outputs, exactly as with the other PIC microcontrollers or they can be switched into analogue mode, in which case they can be used to measure voltages. The 5 analogue channels are handled this way, each mapping onto on pin on PORTA. We have already seen that the 5 pins of PORTA are initially configured as analogue inputs; if you want to use them for the digital projects you have to configure them as digital first.

The PIC microcontroller itself only contains one ADC (Analogue to Digital Converter) but it can be switched between the 8 input channels under program control. This means that if you want to read more than one input you have to take care of looking at each signal in turn. Because the PIC microcontroller runs programs quite quickly, and the conversion is also quite fast, this is possible in all but the most demanding applications.