atmega32c1 ATMEL Corporation, atmega32c1 Datasheet - Page 242

• Manufacturer Part Number: atmega32c1
• Description: Atmega32m1 Automotive 8-bit Avr Microcontroller With 32k/64k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

242
ATmega32/64/M1/C1
Read/Write
Initial Value
• Bit 7, 6 – REFS1, 0: ADC Vref Selection Bits
These 2 bits determine the voltage reference for the ADC.
The different setting are shown in
Table 18-4.
If bits REFS1 and REFS0 are changed during a conversion, the change will not take effect until
this conversion is complete (it means while the ADIF bit in ADCSRA register is set).
In case the internal Vref is selected, it is turned ON as soon as an analog feature needed it is
set.
• Bit 5 – ADLAR: ADC Left Adjust Result
Set this bit to left adjust the ADC result.
Clear it to right adjust the ADC result.
The ADLAR bit affects the configuration of the ADC result data registers. Changing this bit
affects the ADC data registers immediately regardless of any on going conversion. For a com-
plete description of this bit, see Section “ADC Result Data Registers – ADCH and ADCL”,
page 245.
AREFEN
1
1
0
1
1
0
ISRCEN
0
0
0
0
0
x
ADC Voltage Reference Selection
R/W
0
REFS1
0
0
0
1
1
1
R/W
0
REFS0
0
1
1
0
1
1
Table
R/W
0
18-4.
Description
External Vref on AREF pin, Internal Vref is switched off
AVcc with external capacitor connected on the AREF pin
AVcc (no external capacitor connected on the AREF pin)
Reserved
Internal 2.56V Reference voltage with external capacitor
connected on the AREF pin
Internal 2.56V Reference voltage
0
-
R/W
0
R/W
0
R/W
0
R/W
0
7647A–AVR–02/08