ATmega325PA Atmel Corporation, ATmega325PA Datasheet - Page 227

• Manufacturer Part Number: ATmega325PA
• Manufacturer: Atmel Corporation

23.9
23.9.1
8285D–AVR–06/11
Register Description
ADMUX – ADC Multiplexer Selection Register
ATmega165A/PA/325A/PA/3250A/PA/645A/P/6450A/P
• Bit 7:6 – REFS1:0: Reference Selection Bits
These bits select the voltage reference for the ADC, as shown in
changed during a conversion, the change will not go in effect until this conversion is complete
(ADIF in ADCSRA is set). The internal voltage reference options may not be used if an external
reference voltage is being applied to the AREF pin.
Table 23-3.
• Bit 5 – 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 conver-
sions. For a complete description of this bit, see
page
• Bits 4:0 – MUX4:0: Analog Channel Selection Bits
The value of these bits selects which combination of analog inputs are connected to the ADC.
See
in effect until this conversion is complete (ADIF in ADCSRA is set).
Bit
(0x7C)
Read/Write
Initial Value
REFS1
Table 23-4
0
0
1
1
230.
REFS0
Voltage Reference Selections for ADC
0
1
0
1
REFS1
for details. If these bits are changed during a conversion, the change will not go
R/W
7
0
Voltage Reference Selection
AREF, Internal Vref turned off
AVCC with external capacitor at AREF pin
Reserved
Internal 1.1V Voltage Reference with external capacitor at AREF pin
REFS0
R/W
6
0
ADLAR
R/W
5
0
MUX4
R/W
4
0
”ADCL and ADCH – ADC Data Register” on
MUX3
R/W
3
0
MUX2
R/W
2
0
Table
MUX1
R/W
1
0
23-3. If these bits are
MUX0
R/W
0
0
ADMUX
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