ATmega48PA Automotive Atmel Corporation, ATmega48PA Automotive Datasheet - Page 262

• Manufacturer Part Number: ATmega48PA Automotive
• Manufacturer: Atmel Corporation

24.9
24.9.1
262
Register Description
Atmel ATmega48PA/88PA/168PA [Preliminary]
ADMUX – ADC Multiplexer Selection Register
• Bit 7:6 – REFS[1:0]: 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 24-3.
• Bit 5 – ADLAR: ADC Left Adjust Result
The ADLAR bit affects the presentation of the ADC conversion result in the ADC Data Regis-
ter. 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 complete description of this bit, see
Data Register” on page
• Bit 4 – Reserved
This bit is an unused bit in the Atmel
zero.
• Bits 3:0 – MUX[3:0]: Analog Channel Selection Bits
The value of these bits selects which analog inputs are connected to the ADC. See
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).
Bit
(0x7C)
Read/Write
Initial Value
REFS1
0
0
1
1
REFS0
Voltage Reference Selections for ADC
REFS1
0
1
0
1
R/W
7
0
Voltage Reference Selection
AREF, Internal V
AV
Reserved
Internal 1.1V Voltage Reference with external capacitor at AREF pin
REFS0
265.
R/W
CC
6
0
with external capacitor at AREF pin
ADLAR
R/W
5
0
ref
®
turned off
ATmega48PA/88PA/168PA, and will always read as
R
4
–
0
MUX3
R/W
3
0
MUX2
R/W
2
0
“ADCL and ADCH – The ADC
Table
MUX1
R/W
1
0
24-3. If these bits are
MUX0
R/W
0
0
9223B–AVR–09/11
Table 24-4
ADMUX