at90pwm81-16se ATMEL Corporation, at90pwm81-16se Datasheet - Page 217

• Manufacturer Part Number: at90pwm81-16se
• Description: 8-bit Avr Microcontroller With 8k Bytes In- System Programmable Flash
• Manufacturer: ATMEL Corporation

7734M–AVR–03/10
• Bit 7, 6 – REFS1, 0: ADC Vref Selection Bits
These 2 bits determine the voltage reference for the ADC and for the other analog devices.
The different setting are shown in
Table 18-3.
If these bits are changed during a conversion, the change will not take effect until this conversion is com-
plete (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 complete description of this
bit, see Section “ADC Result Data Registers – ADCH and ADCL”, page 220.
• Bit 3, 2, 1, 0 – MUX3, MUX2, MUX1, MUX0: ADC Channel Selection Bits
These 4 bits determine which analog inputs are connected to the ADC input. The different setting are
shown in
Table 18-4.
REFS1
0
0
1
1
MUX3
0
0
0
0
0
0
0
0
1
1
1
1
1
Table
REFS0
0
1
0
1
18-4.
ADC Voltage Reference Selection
ADC Input Channel Selection
MUX2
0
0
0
0
1
1
1
1
0
0
0
0
1
Description
Voltage Reference
External Vref
AVcc
Internal 2.56V Reference voltage
Internal 2.56V Reference voltage
MUX1
0
0
1
1
0
0
1
1
0
0
1
1
0
Table
18-3.
MUX0
0
1
0
1
0
1
0
1
0
1
0
1
0
Description
ADC0
ADC1
ADC2
ADC3
ADC4
ADC5
ADC6
ADC7
ADC8
ADC9
ADC10
AMP0
Temp sensor (Vtemp)
PE3/AREF pin
External Voltage reference
External capacitor for decoupling of the
Internal Reference voltage
PE3 pin free as port
AT90PWM81
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