ATmega88 Atmel Corporation, ATmega88 Datasheet - Page 255

• Manufacturer Part Number: ATmega88
• Manufacturer: Atmel Corporation

Specifications of ATmega88

• Flash (kbytes): 8 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 20 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 23
• Ext Interrupts: 24
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 1
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 6
• Input Capture Channels: 1
• Pwm Channels: 6
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

24.7
24.8
24.8.1
2545T–AVR–05/11
ADC conversion result
Register description
ADMUX – ADC multiplexer selection register
After the conversion is complete (ADIF is high), the conversion result can be found in the ADC
Result Registers (ADCL, ADCH).
For single ended conversion, the result is
where V
Table 24-2
sents 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 24-2.
• 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
• Bit 4 – Res: Reserved bit
This bit is an unused bit in the Atmel ATmega48/88/168, and will always read as zero.
Bit
(0x7C)
Read/write
Initial value
REFS1
0
0
1
1
258.
IN
is the voltage on the selected input pin and V
and
REFS0
REFS1
Voltage reference selections for ADC.
R/W
0
1
0
1
7
0
Table 24-3 on page
REFS0
Voltage reference selection
AREF, internal V
AV
Reserved
Internal 1.1V voltage reference with external capacitor at AREF pin
R/W
6
0
CC
with external capacitor at AREF pin
ADLAR
R/W
5
0
256). 0x000 represents analog ground, and 0x3FF repre-
ADC
ref
turned off
R
4
–
0
=
V
--------------------------
MUX3
IN
R/W
V
“ADCL and ADCH – The ADC data register” on
3
0
⋅
REF
1024
MUX2
R/W
REF
2
0
the selected voltage reference (see
ATmega48/88/168
MUX1
R/W
1
0
Table
MUX0
R/W
0
0
24-2. If these bits are
ADMUX
255