ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 55

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

11.9
11.9.1
9223B–AVR–09/11
Register Description
MCUSR – MCU Status Register
The MCU Status Register provides information on which reset source caused an MCU reset.
• Bit 7:4: Reserved
These bits are unused bits in the Atmel
zero.
• Bit 3 – WDRF: Watchdog System Reset Flag
This bit is set if a Watchdog System 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
0x34 (0x54)
Read/Write
Initial Value
Atmel ATmega48PA/88PA/168PA [Preliminary]
R
7
–
0
6
–
R
0
R
5
–
0
®
ATmega48PA/88PA/168PA, and will always read as
R
4
–
0
WDRF
R/W
3
See Bit Description
BORF
R/W
2
EXTRF
R/W
1
PORF
R/W
0
MCUSR
55