ATMEGA8L ATMEL [ATMEL Corporation], ATMEGA8L Datasheet - Page 190

• Manufacturer Part Number: ATMEGA8L
• Description: 8-bit AVR with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Analog Comparator
Special Function IO Register –
SFIOR
190
ATmega8(L)
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 89.
Figure 89. Analog Comparator Block Diagram
Notes:
• 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 192.
Bit
Read/Write
Initial Value
ADC MULTIPLEXER
REFERENCE
ACME
ADEN
BANDGAP
OUTPUT
1. See Table 72 on page 192.
2. Refer to “Pin Configurations” on page 2 and Table 28 on page 61 for Analog Compar-
ator pin placement.
ACBG
(1)
R
7
–
0
R
6
–
0
R
5
–
0
R
4
–
0
(2)
ACME
R/W
3
0
PUD
R/W
2
0
PSR2
R/W
1
0
PSR10
R/W
2486M–AVR–12/03
0
0
SFIOR