Table 74. Voltage Reference Selections for ADC
REFS1
REFS0 Voltage Reference Selection
0
1
1
1
0
1
AVCC with external capacitor at AREF pin
Reserved
Internal 2.56V Voltage Reference with external capacitor at AREF pin
•
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 “The ADC Data Register – ADCL and ADCH” on
page 208.
• Bits 3:0 – MUX3:0: Analog Channel Selection Bits
The value of these bits selects which analog inputs are connected to the ADC. See Table 75 for
details. If these bits are changed during a conversion, the change will not go in effect until this
conversion is complete (ADIF in ADCSRA is set).
Table 75. Input Channel Selections
MUX3..0
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Single Ended Input
ADC0
ADC1
ADC2
ADC3
ADC4
ADC5
ADC6
ADC7
1.30V (VBG
)
0V (GND)
206
ATmega8(L)
2486T–AVR–05/08
ATMEL [ ATMEL ]
