ATMEGA325-16AJ ATMEL [ATMEL Corporation], ATMEGA325-16AJ Datasheet - Page 42

• Manufacturer Part Number: ATMEGA325-16AJ
• Description: 8-bit Microcontroller with In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

MCU Status Register –
MCUSR
42
ATmega325/3250/645/6450
Figure 20. Watchdog Reset During Operation
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 3 – WDRF: Watchdog Reset Flag
This bit is set if a Watchdog Reset occurs. The bit is reset by a Power-on Reset, or by
writing a logic zero to the flag.
• Bit 2 – BORF: Brown-out Reset Flag
This bit is set if a Brown-out Reset occurs. The bit is reset by a Power-on Reset, or by
writing a logic zero to the flag.
• Bit 1 – EXTRF: External Reset Flag
This bit is set if an External Reset occurs. The bit is reset by a Power-on Reset, or by
writing a logic zero to the flag.
• Bit 0 – PORF: Power-on Reset Flag
This bit is set if a Power-on Reset occurs. The bit is reset only by writing a logic zero to
the flag.
To make use of the Reset Flags to identify a reset condition, the user should read and
then Reset the MCUSR as early as possible in the program. If the register is cleared
before another reset occurs, the source of the reset can be found by examining the
Reset Flags.
Bit
Read/Write
Initial Value
CC
R
7
–
0
R
6
–
0
R
5
–
0
CK
JTRF
R/W
4
WDRF
R/W
3
See Bit Description
BORF
R/W
2
EXTRF
R/W
1
PORF
R/W
2570A–AVR–09/04
0
MCUSR