
113
ATtiny40 [DATASHEET]
8263B–AVR–01/2013
Bit 3 – ADLAR: ADC Left Adjust Result
The ADLAR bit affects the presentation of the ADC conversion result in the ADC Data Register. Write one to
ADLAR to left adjust the result. Otherwise, the result is right adjusted. Changing the ADLAR bit will affect the ADC
Data Register immediately, regardless of any ongoing conversions. For a comple the description of this bit, see
Bits 2:0 – ADTS[2:0]: ADC Auto Trigger Source
If ADATE in ADCSRA is written to one, the value of these bits selects which source will trigger an ADC conversion.
If ADATE is cleared, the ADTS[2:0] settings will have no effect. A conversion will be triggered by the rising edge of
the selected Interrupt Flag. Note that switching from a trigger source that is cleared to a trigger source that is set,
will generate a positive edge on the trigger signal. If ADEN in ADCSRA is set, this will start a conversion. Switching
to Free Running mode (ADTS[2:0]=0) will not cause a trigger event, even if the ADC Interrupt Flag is set
.
15.13.5
DIDR0 – Digital Input Disable Register 0
Bits 7:0 – ADC7D:ADC0D: ADC[7:0] Digital Input Disable
When a bit is written logic one, the digital input buffer on the corresponding ADC pin is disabled. The correspond-
ing PIN register bit will always read as zero when this bit is set. When an analog signal is applied to the ADC[7:0]
pin and the digital input from this pin is not needed, this bit should be written logic one to reduce power consump-
tion in the digital input buffer.
15.13.6
PORTCR – Port Control Register
Bits 7:4 – ADC11D:ADC8D: ADC[11:8] Digital Input Disable
When a bit is written logic one, the digital input buffer on the corresponding ADC pin is disabled. The correspond-
ing PIN register bit will always read as zero when this bit is set. When an analog signal is applied to the ADC[11:8]
pin and the digital input from this pin is not needed, this bit should be written logic one to reduce power consump-
tion in the digital input buffer.
Table 15-6.
ADC Auto Trigger Source Selections
ADTS2
ADTS1
ADTS0
Trigger Source
0
Free Running mode
0
1
Analog Comparator
0
1
0
External Interrupt Request 0
0
1
Timer/Counter0 Compare Match A
1
0
Timer/Counter0 Overflow
1
0
1
Timer/Counter1 Compare Match B
1
0
Timer/Counter1 Overflow
1
Timer/Counter1 Capture Event
Bit
765
432
10
ADC7D
ADC6D
ADC5D
ADC4D
ADC3D
ADC2D
ADC1D
ADC0D
DIDR0
Read/Write
R/W
Initial Value
000
00
Bit
765
432
10
ADC11D
ADC10D
ADC9D
ADC8D
–
BBMC
BBMB
BBMA
PORTCR
Read/Write
R/W
R
R/W
Initial Value
000
00