ATMEGA644A-PU Atmel, ATMEGA644A-PU Datasheet - Page 276

• 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

24.8
24.8.1
24.8.2
8272A–AVR–01/10
Register Description
MCUCR – MCU Control Register
MCUSR – MCU Status Register
The MCU Control Register contains control bits for general MCU functions.
Note:
• Bits 7 – JTD: JTAG Interface Disable
When this bit is zero, the JTAG interface is enabled if the JTAGEN Fuse is programmed. If this
bit is one, the JTAG interface is disabled. In order to avoid unintentional disabling or enabling of
the JTAG interface, a timed sequence must be followed when changing this bit: The application
software must write this bit to the desired value twice within four cycles to change its value. Note
that this bit must not be altered when using the On-chip Debug system.
The MCU Status Register provides information on which reset source caused an MCU reset.
• Bit 4 – JTRF: JTAG Reset Flag
This bit is set if a reset is being caused by a logic one in the JTAG Reset Register selected by
the JTAG instruction AVR_RESET. This bit is reset by a Power-on Reset, or by writing a logic
zero to the flag.
164A/164PA/324A/324PA/644A/644PA/1284/1284P
Bit
0x35 (0x55)
Read/Write
Initial Value
Bit
0x34 (0x54)
Read/Write
Initial Value
1. Only available in the ATmega164PA/324PA/644PA/1284P.
JTD
R/W
7
0
R
7
–
0
BODS
R
6
0
R
6
–
0
(1)
BODSE
R
5
0
R
5
–
0
(1)
PUD
JTRF
R/W
R/W
4
0
4
WDRF
R/W
R
3
–
0
3
See Bit Description
BORF
R/W
R
2
–
0
2
IVSEL
EXTRF
R/W
R/W
1
0
1
IVCE
PORF
R/W
R/W
0
0
0
MCUCR
MCUSR
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