ATmega8 Atmel Corporation, ATmega8 Datasheet - Page 186

• Manufacturer Part Number: ATmega8
• Manufacturer: Atmel Corporation

Specifications of ATmega8

• Flash (kbytes): 8 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 23
• Ext Interrupts: 2
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• 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: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 1
• Pwm Channels: 3
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

Analog
Comparator
Special Function IO
Register – SFIOR
Analog Comparator
Control and Status
Register – ACSR
186
ATmega8(L)
The Analog Comparator compares the input values on the positive pin AIN0 and negative pin
AIN1. When the voltage on the positive pin AIN0 is higher than the voltage on the negative pin
AIN1, the Analog Comparator Output, ACO, is set. The comparator’s output can be set to trigger
the Timer/Counter1 Input Capture function. In addition, the comparator can trigger a separate
interrupt, exclusive to the Analog Comparator. The user can select Interrupt triggering on com-
parator output rise, fall or toggle. A block diagram of the comparator and its surrounding logic is
shown in
Figure 89. Analog Comparator Block Diagram
Notes:
• Bit 3 – ACME: Analog Comparator Multiplexer Enable
When this bit is written logic one and the ADC is switched off (ADEN in ADCSRA is zero), the
ADC multiplexer selects the negative input to the Analog Comparator. When this bit is written
logic zero, AIN1 is applied to the negative input of the Analog Comparator. For a detailed
description of this bit, see
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
ADC MULTIPLEXER
REFERENCE
ACME
ADEN
BANDGAP
1. See
2. Refer to
Figure
OUTPUT
placement
R
7
–
0
ACD
R/W
Table 72 on page 188
7
0
89.
ACBG
(1)
“Pin Configurations” on page 2
ACBG
R/W
R
6
–
0
6
0
“Analog Comparator Multiplexed Input” on page
ACO
N/A
R
R
5
5
–
0
R/W
ACI
4
0
R
4
–
0
(2)
ACIE
R/W
and
ACME
3
0
R/W
3
0
Table 28 on page 63
ACIC
R/W
2
0
PUD
R/W
2
0
ACIS1
R/W
PSR2
1
0
R/W
1
0
ACIS0
for Analog Comparator pin
PSR10
R/W
R/W
0
0
0
0
188.
ACSR
SFIOR
2486Z–AVR–02/11