Datasheet

213
7728G–AVR–06/10
ATtiny87/ATtiny167
Note: When changing the ACIS1/ACIS0 bits, the Analog Comparator Interrupt must be disabled by
clearing its Interrupt Enable bit in the ACSR Register. Otherwise an interrupt can occur when
the bits are changed.
18.1.3 DIDR0 – Digital Input Disable Register 0
• Bits 7,6 – AIN1D, AIN0D: AIN1D and AIN0D Digital Input Disable
When this bit is written logic one, the digital input buffer on the corresponding Analog Com-
pare pin is disabled. The corresponding PIN register bit will always read as zero when this bit
is set. When an analog signal is applied to the AIN0/1 pin and the digital input from this pin is
not needed, this bit should be written logic one to reduce power consumption in the digital
input buffer.
18.2 Analog Comparator Inputs
18.2.1 Analog Compare Positive Input
It is possible to select any of the inputs of the ADC Positive Input Multiplexer to replace the
positive input to the Analog Comparator. The ADC multiplexer is used to select this input, and
consequently, the ADC must be switched off to utilize this feature. If the Analog Comparator
Multiplexer Enable bit (ACME in ADCSRB register) is set and the ADC is switched off (ADEN
in ADCSRA register is zero), MUX[4..0] in ADMUX register select the input pin to replace the
positive input to the Analog Comparator, as shown in Table 18-2. If ACME is cleared or ADEN
is set, AIN1 pin is applied to the positive input to the Analog Comparator.
Table 18-1. ACIS1 / ACIS0 Settings
ACIS1 ACIS0 Interrupt Mode
0 0 Comparator Interrupt on Output Toggle.
01Reserved
1 0 Comparator Interrupt on Falling Output Edge.
1 1 Comparator Interrupt on Rising Output Edge.
Bit 76543210
ADC7D /
AIN1D
ADC6D /
AIN0D
ADC5D ADC4D ADC3D ADC2D ADC1D ADC0D DIDR0
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000