The Analog Comparator compares the input values on the positive pin AIN0 and negative pin AIN1. When the voltage on the positive pin AIN0 is higher than the voltage on the negative pin AIN1, the Analog Comparator Output, ACO, is set. The comparator’s output can be set to trigger the Timer/Counter1 Input Capture function. In addition, the comparator can trigger a separate interrupt, exclusive to the Analog Comparator. The user can select Interrupt triggering on comparator output rise, fall or toggle. A block diagram of the comparator and its surrounding logic is shown in the figure below.

Figure 1. Analog Comparator Block Diagram(2)
  1. 1.See Table Analog Comparator Multiplexed Input in next section.
  2. 2.Refer to the Pin Configuration and the Port D Pins Alternate Functions Table.