ATmega644P Atmel Corporation, ATmega644P Datasheet - Page 237
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ATmega644P
Manufacturer Part Number
ATmega644P
Description
Manufacturer
Atmel Corporation
Specifications of ATmega644P
Flash (kbytes)
64 Kbytes
Pin Count
44
Max. Operating Frequency
20 MHz
Cpu
8-bit AVR
# Of Touch Channels
16
Hardware Qtouch Acquisition
No
Max I/o Pins
32
Ext Interrupts
32
Usb Speed
No
Usb Interface
No
Spi
3
Twi (i2c)
1
Uart
2
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)
4
Eeprom (bytes)
2048
Self Program Memory
YES
Dram Memory
No
Nand Interface
No
Picopower
Yes
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
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19. AC - Analog Comparator
19.1
19.2
8011O–AVR–07/10
Overview
Analog Comparator Multiplexed Input
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
The Power Reduction ADC bit, PRADC, in
be disabled by writing a logical zero to be able to use the ADC input MUX.
Figure 19-1. Analog Comparator Block Diagram
Notes:
It is possible to select any of the ADC7..0 pins to replace the negative input to the Analog Com-
parator. The ADC multiplexer is used to select this input, and consequently, the ADC must be
switched off to utilize this feature. If the Analog Comparator Multiplexer Enable bit (ACME in
ADCSRB) is set and the ADC is switched off (ADEN in ADCSRA is zero), MUX2..0 in ADMUX
select the input pin to replace the negative input to the Analog Comparator, as shown in
19-1 on page
Analog Comparator.
Table 19-1.
ACME
0
1
1
ADC MULTIPLEXER
1. See
2. Refer to
Figure
REFERENCE
ACME
ADEN
BANDGAP
OUTPUT
placement.
237. If ACME is cleared or ADEN is set, AIN1 is applied to the negative input to the
Analog Comparator Mulitiplexed Input
Table 19-1 on page
(1)
19-1.
ACBG
Figure 1-1 on page 2
ADEN
1
0
x
237.
MUX2..0
000
xxx
xxx
and
”PRR – Power Reduction Register” on page 48
Table 11-5 on page 81
Analog Comparator Negative Input
AIN1
AIN1
ADC0
ATmega164P/324P/644P
(2)
for Analog Comparator pin
Table
must
237