ATMEGA164P-20AQ Atmel, ATMEGA164P-20AQ Datasheet - Page 275

• Manufacturer Part Number: ATMEGA164P-20AQ
• Description: MCU AVR 16K FLASH 20MHZ 44-TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA164P-20AQ

• 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: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• For Use With: ATSTK600-TQFP44 - STK600 SOCKET/ADAPTER 44-TQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

22.8
22.8.1
22.8.2
8011O–AVR–07/10
Register Description
MCUCR – MCU Control Register
MCUSR – MCU Status Register
The MCU Control Register contains control bits for general MCU functions.
• 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.
Bit
0x35 (0x55)
Read/Write
Initial Value
Bit
0x34 (0x54)
Read/Write
Initial Value
JTD
R/W
7
0
R
7
–
0
BODS
R
6
0
R
6
–
0
BODSE
R
5
0
R
5
–
0
JTRF
PUD
R/W
R/W
4
0
4
ATmega164P/324P/644P
WDRF
R/W
R
3
–
0
3
See Bit Description
BORF
R/W
R
2
–
0
2
EXTRF
IVSEL
R/W
R/W
1
0
1
PORF
IVCE
R/W
R/W
0
0
0
MCUCR
MCUSR
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