AT90USB1286-16MU ATMEL [ATMEL Corporation], AT90USB1286-16MU Datasheet - Page 62

• Manufacturer Part Number: AT90USB1286-16MU
• Description: Microcontroller with 64/128K Bytes of ISP Flash and USB Controller
• Manufacturer: ATMEL [ATMEL Corporation]

8.0.6
8.0.7
62
AT90USB64/128
Watchdog Reset
MCU Status Register – MCUSR
When the Watchdog times out, it will generate a short reset pulse of one CK cycle duration. On
the falling edge of this pulse, the delay timer starts counting the Time-out period t
page 63
Figure 8-6.
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
for details on operation of the Watchdog Timer.
CC
7
–
R
0
Watchdog Reset During Operation
R
6
–
0
5
–
R
0
CK
4
JTRF
R/W
See Bit Description
3
WDRF
R/W
2
BORF
R/W
1
EXTRF
R/W
0
PORF
R/W
MCUSR
TOUT
7593A–AVR–02/06
. Refer to