Most micros with ADCs have multiplexed inputs. You may have several sensors, each connected to its own input. For example you might have a couple of analog temperature sensors and a potentiometer to set on/off points.My Atmega32 has as many as 8 ADC pins (outputs). So far I've only needed to use one. In what situation would anyone need to use more?
Can they be used to operate more than one project at a time?
Can the multiplexing process be programed into the Atmega32?
Yup, its works the same way. Tell it to read, come back later or let it interrupt you and get the reading from it. Change channels if you desire, and tell it to read again if you desire.Of course, on a PIC you select which input you want to read, take the reading, store it (or do what ever you want with it), then select the next input and so on.
I would imagine the AVR works in a similar fashion (as other devices do).