Datasheet

227
2490R–AVR–02/2013
ATmega64(L)
Analog
Comparator
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 com-
parator output rise, fall or toggle. A block diagram of the comparator and its surrounding logic is
shown in Figure 107.
Figure 107. Analog Comparator Block Diagram
(1)(2)
Notes: 1. See Table 94 on page 229.
2. Refer to Figure 1 on page 2 and Table 30 on page 74 for Analog Comparator pin placement.
SFIOR – Special
Function IO Register
• Bit 3 – ACME: Analog Comparator Multiplexer Enable
When this bit is written logic one and the ADC is switched off (ADEN in ADCSRA is zero), the
ADC multiplexer selects the negative input to the Analog Comparator. When this bit is written
logic zero, AIN1 is applied to the negative input of the Analog Comparator. For a detailed
description of this bit, see “Analog Comparator Multiplexed Input” on page 229.
ACBG
BANDGAP
REFERENCE
ADC MULTIPLEXER
OUTPUT
ACME
ADEN
1)
Bit 7 6 5 4 3 2 1 0
0x20
(0x40)
TSM – – – ACME PUD PSR2 PSR10 SFIOR
Read/Write R/W R R R R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0