ATMEGA8A-AU Atmel, ATMEGA8A-AU Datasheet - Page 208

• Manufacturer Part Number: ATMEGA8A-AU
• Description: MCU AVR 8K FLASH 16MHZ 32-TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8A-AU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-TQFP, 32-VQFP
• Processor Series: ATMEGA8x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 1 KB
• Interface Type: SPI, TWI, USART
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 23
• Number Of Timers: 3
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 8 Channel
• Controller Family/series: AVR MEGA
• No. Of I/o's: 23
• Eeprom Memory Size: 512Byte
• Ram Memory Size: 1KB
• Cpu Speed: 16MHz
• Rohs Compliant: Yes
• For Use With: ATSTK600 - DEV KIT FOR AVR/AVR32ATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

22.8
22.8.1
8159D–AVR–02/11
Register Description
ADMUX – ADC Multiplexer Selection Register – ADMUX
where V
Table 22-2 on page 208
represents the selected reference voltage minus one LSB.
• Bit 7:6 – REFS1:0: 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 22-2.
• 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
page
• Bits 3:0 – MUX3:0: 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
Read/Write
Initial Value
REFS1
0
0
1
1
210.
IN
is the voltage on the selected input pin and V
REFS0
REFS1
Voltage Reference Selections for ADC
R/W
0
1
0
1
7
0
Voltage Reference Selection
AREF, Internal V
AV
Reserved
Internal 2.56V Voltage Reference with external capacitor at AREF pin
REFS0
R/W
6
0
CC
and
with external capacitor at AREF pin
Table 22-3 on page
ADLAR
R/W
5
0
ref
turned off
R
4
–
0
“ADCL and ADCH – The ADC Data Register” on
MUX3
209). 0x000 represents ground, and 0x3FF
R/W
3
0
REF
the selected voltage reference (see
MUX2
R/W
2
0
Table
MUX1
R/W
1
0
22-2. If these bits are
ATmega8A
MUX0
R/W
0
0
Table 22-3
ADMUX
208