ATMEGA644A-PU Atmel, ATMEGA644A-PU Datasheet - Page 239
![IC MCU AVR 64K FLASH 40PDIP](/photos/6/70/67049/453-40-dip_sml.jpg)
ATMEGA644A-PU
Manufacturer Part Number
ATMEGA644A-PU
Description
IC MCU AVR 64K FLASH 40PDIP
Manufacturer
Atmel
Series
AVR® ATmegar
Specifications of ATMEGA644A-PU
Core Processor
AVR
Core Size
8-Bit
Speed
20MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
32
Program Memory Size
64KB (32K x 16)
Program Memory Type
FLASH
Eeprom Size
2K x 8
Ram Size
4K x 8
Voltage - Supply (vcc/vdd)
1.8 V ~ 5.5 V
Data Converters
A/D 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
40-DIP (0.600", 15.24mm)
Processor Series
ATmega
Core
AVR
Data Bus Width
8 bit
Data Ram Size
4 KB
Interface Type
JTAG, TWI, SPI, USART
Maximum Clock Frequency
20 MHz
Number Of Programmable I/os
32
Number Of Timers
3
Operating Supply Voltage
3.3 V
Maximum Operating Temperature
+ 85 C
Mounting Style
Through Hole
Minimum Operating Temperature
- 40 C
Operating Temperature Range
- 40 C to + 85 C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
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21.3
21.3.1
21.3.2
8272A–AVR–01/10
Register Description
ADCSRB – ADC Control and Status Register B
ACSR – Analog Comparator Control and Status Register
Table 21-1.
• Bit 6 – 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 7 – ACD: Analog Comparator Disable
When this bit is written logic one, the power to the Analog Comparator is switched off. This bit
can be set at any time to turn off the Analog Comparator. This will reduce power consumption in
Active and Idle mode. When changing the ACD bit, the Analog Comparator Interrupt must be
disabled by clearing the ACIE bit in ACSR. Otherwise an interrupt can occur when the bit is
changed.
• Bit 6 – ACBG: Analog Comparator Bandgap Select
When this bit is set, a fixed bandgap reference voltage replaces the positive input to the Analog
Comparator. When this bit is cleared, AIN0 is applied to the positive input of the Analog Compar-
ator. When bandgap reference is used as input to the Analog Comparator, it will take a certain
time for the voltage to stabilize. If not stabilized, the first conversion may give wrong value. See
”Internal Voltage Reference” on page
• Bit 5 – ACO: Analog Comparator Output
The output of the Analog Comparator is synchronized and then directly connected to ACO. The
synchronization introduces a delay of 1 - 2 clock cycles.
164A/164PA/324A/324PA/644A/644PA/1284/1284P
Bit
(0x7B)
Read/Write
Initial Value
Bit
0x30 (0x50)
Read/Write
Initial Value
ACME
1
1
1
1
1
1
1
Analog Comparator Mulitiplexed Input
ACD
R/W
R
7
0
7
–
0
ADEN
0
0
0
0
0
0
0
ACBG
ACME
R/W
R/W
”Analog Comparator Multiplexed Input” on page
6
0
6
0
ACO
N/A
MUX2..0
R
5
R
5
–
0
001
010
011
100
101
110
111
55.
R/W
ACI
4
0
R
4
–
0
Analog Comparator Negative Input
ADC1
ADC2
ADC3
ADC4
ADC5
ADC6
ADC7
ACIE
R/W
3
0
R
3
0
-
ADTS2
ACIC
R/W
R/W
2
0
2
0
ADTS1
ACIS1
R/W
R/W
1
0
1
0
238.
ADTS0
ACIS0
R/W
R/W
0
0
0
0
ADCSRB
ACSR
239
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