attiny13-20ss ATMEL Corporation, attiny13-20ss Datasheet - Page 77

• Manufacturer Part Number: attiny13-20ss
• Description: 8-bit Microcontroller With 1k Bytes In-system Programmable Flash - Atmel Corporation
• Manufacturer: ATMEL Corporation

Analog Comparator
ADC Control and Status
Register B – ADCSRB
Analog Comparator Control
and Status Register – ACSR
2535G–AVR–01/07
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 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 com-
parator and its surrounding logic is shown in Figure 39.
Figure 39. Analog Comparator Block Diagram
Notes:
• Bit 6 – 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 79.
• Bit 7 – ACD: Analog Comparator Disable
When this bit is written logic one, the power to the Analog Comparator is switched off.
This bit can be set at any time to turn off the Analog Comparator. This will reduce power
consumption in Active and Idle mode. When changing the ACD bit, the Analog Compar-
ator Interrupt must be disabled by clearing the ACIE bit in ACSR. Otherwise an interrupt
can occur when the bit is changed.
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
ADC MULTIPLEXER
REFERENCE
ACME
ADEN
OUTPUT
BANDGAP
1. See Table 35 on page 79.
2. Refer to Figure 1 on page 2 and Table 23 on page 52 for Analog Comparator pin
placement.
(1)
ACD
R/W
ACBG
R
7
0
7
–
0
ACBG
ACME
R/W
R/W
6
0
6
0
ACO
N/A
R
5
R
5
–
0
R/W
ACI
4
0
R
4
–
0
(2)
ACIE
R/W
3
0
R
3
–
0
ADTS2
R/W
R
2
–
0
2
0
ACIS1
ADTS1
R/W
R/W
1
0
1
0
ACIS0
ADTS0
R/W
R/W
0
0
0
0
ADCSRB
ACSR
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