ATTINY26L8SU SL383 Atmel, ATTINY26L8SU SL383 Datasheet - Page 103

• Manufacturer Part Number: ATTINY26L8SU SL383
• Description: MCU 8-Bit ATtiny AVR RISC 2KB Flash 3.3V/5V 20-Pin SOIC T/R
• Manufacturer: Atmel

ADC Multiplexer Selection
Register – ADMUX
1477J–AVR–06/07
• Bit 7, 6 – REFS1, REFS0: Reference Selection Bits
These bits select the voltage reference for the ADC, as shown in Table 45. If these bits
are changed during a conversion, the change will not go in effect until this conversion is
complete (ADIF in ADCSR is set). The user should disregard the first conversion result
after changing these bits to obtain maximum accuracy. If differential channels are used,
using AVCC or an external AREF higher than (AVCC - 0.2V) is not recommended, as
this will affect ADC accuracy. The internal voltage reference may not be used if an
external reference voltage is being applied to the AREF pin.
Table 45. Voltage Reference Selections for ADC
•
The ADLAR bit affects the presentation of the ADC conversion result in the ADC Data
Register. If ADLAR is cleared, the result is right adjusted. If ADLAR is set, the result is
left 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 “ADC
Data Register – ADCL and ADCH” on page 106.
• Bits 4..0 – MUX4..MUX0: Analog Channel and Gain Selection Bits
The value of these bits selects which combination of analog inputs are connected to the
ADC. These bits also select the gain for the differential channels. See Table 46 for
details. If these bits are changed during a conversion, the change will not go in effect
until this conversion is complete (ADIF in ADCSR is set).
Bit
$07 ($27)
Read/Write
Initial Value
REFS1
Bit 5 – ADLAR: ADC Left Adjust Result
0
0
1
1
REFS0
0
1
0
1
REFS1
R/W
7
0
Voltage Reference Selection
AVCC
AREF (PA3), Internal Vref turned off.
Internal Voltage Reference (2.56 V), AREF pin (PA3) not connected.
Internal Voltage Reference (2.56 V) with external capacitor at AREF pin
(PA3).
REFS0
R/W
6
0
ADLAR
R/W
5
0
MUX4
R/W
4
0
MUX3
R/W
3
0
MUX2
R/W
2
0
MUX1
R/W
ATtiny26(L)
1
0
MUX0
R/W
0
0
ADMUX
103