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Atmel ATmega16/32/64/M1/C1 [DATASHEET]
7647K–AVR–12/13
20.4.2 Analog Comparator 1 Control Register – AC1CON
Bit 7– AC1EN: Analog Comparator 1 Enable Bit
Set this bit to enable the analog comparator 1.
Clear this bit to disable the analog comparator 1.
Bit 6– AC1IE: Analog Comparator 1 Interrupt Enable bit
Set this bit to enable the analog comparator 1 interrupt.
Clear this bit to disable the analog comparator 1 interrupt.
Bit 5, 4– AC1IS1, AC1IS0: Analog Comparator 1 Interrupt Select bit
These 2 bits determine the sensitivity of the interrupt trigger.
Bit 3– AC1ICE: analog comparator 1 Interrupt Capture Enable bit
Set this bit to enable the input capture of the Timer/Counter1 on the analog comparator event. The comparator output is in this
case directly connected to the input capture front-end logic, making the comparator utilize the noise canceler and edge select
features of the Timer/Counter1 input capture interrupt. To make the comparator trigger the Timer/Counter1 input capture
interrupt, the ICIE1 bit in the timer interrupt mask register (TIMSK1) must be set.
AC1O is the capture/trigger event of the Timer/Counter1, in case ICES1 is set to zero, it is the falling edge which is taken into
account.
Clear this bit to disable this function. In this case, no connection between the analog comparator and the input capture function
exists.
Bit 2, 1, 0– AC1M2, AC1M1, AC1M0: analog comparator 1 Multiplexer register
These 3 bits determine the input of the negative input of the analog comparator.
Table 20-2. Analog Comparator 0 Negative Input Selection
AC0M2
AC0M1
AC0M0
Description
0
“Vref”/6.40
0
1
“Vref”/3.20
0
1
0
“Vref”/2.13
0
1
“Vref”/1.60
1
0
Bandgap (1.1V)
1
0
1
DAC result
1
0
Analog comparator negative input (ACMPM pin)
1
Reserved
Bit
7
6
5
4
3210
AC1EN
AC1IE
AC1IS1
AC1IS0
AC1ICE
AC1M2
AC1M1
AC1M0
AC1CON
Read/Write
R/W
Initial Value
0
0000
Table 20-3. Interrupt Sensitivity Selection
AC1IS1
AC1IS0
Description
0
Comparator Interrupt on output toggle
0
1
Reserved
1
0
Comparator interrupt on output falling edge
1
Comparator interrupt on output rising edge