Analog Comparator
The Analog Comparator compares the input values on the positive pin AIN0 and nega-
tive 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 dia-
gram of the comparator and its surrounding logic is shown in Figure 97.
Figure 97. Analog Comparator Block Diagram(2)
BANDGAP
REFERENCE
ACBG
ACME
ADEN
ADC MULTIPLEXER
OUTPUT(1)
Notes: 1. See Table 80 on page 200.
2. Refer to Figure 1 on page 2 and Table 25 on page 57 for Analog Comparator pin
placement.
Special Function IO Register –
SFIOR
Bit
7
ADTS2
R/W
0
6
ADTS1
R/W
0
5
ADTS0
R/W
0
4
–
3
ACME
R/W
0
2
1
PSR2
R/W
0
0
PSR10
R/W
0
PUD
R/W
0
SFIOR
Read/Write
Initial Value
R
0
• 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 Compar-
ator. For a detailed description of this bit, see “Analog Comparator Multiplexed Input” on
page 200.
198
ATmega32(L)
2503J–AVR–10/06
ATMEL [ ATMEL ]
