MEGA128CAN Datasheet, PDF (262/413 Pages) ATMEL Corporation – Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER

Analog Comparator
Overview
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 diagram of the com-
parator and its surrounding logic is shown in Figure 126.
Figure 126. Analog Comparator Block Diagram⁽¹⁾⁽²⁾
BANDGAP
REFERENCE
ACBG
ACME
ADEN
ADC
MULTIPLEXER
OUTPUT
T/C1 INPUT CAPTURE
Analog Comparator
Register Description
ADC Control and Status
Register B – ADCSRB
Analog Comparator Control
and Status Register – ACSR
Notes: 1. ADC multiplexer output: see Table 98 on page 264.
2. Refer to Figure 2 on page 4 and Table 41 on page 78 for Analog Comparator pin
placement.
Bit
7
6
5
4
3
2
1
0
ADHSM ACME
–
–
–
ADTS2 ADTS1 ADTS0 ADCSRB
Read/Write
R/W
R/W
R
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
• 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 264.
Bit
Read/Write
Initial Value
7
6
5
4
3
2
1
0
ACD
ACBG
ACO
ACI
ACIE
ACIC ACIS1 ACIS0
ACSR
R/W
R/W
R
R/W
R/W
R/W
R/W
R/W
0
0
N/A
0
0
0
0
0
262 AT90CAN128
4250E–CAN–12/04