MEGA128CAN Datasheet, PDF (51/413 Pages) ATMEL Corporation – Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER

Watchdog Reset
AT90CAN128
The BOD circuit will only detect a drop in V_CC if the voltage stays below the trigger level
for longer than t_BOD given in Table 19.
Figure 27. Brown-out Reset During Operation
V_CC
V_BOT-
V_BOT+
RESET
TIME-OUT
t_TOUT
INTERNAL
RESET
When the Watchdog times out, it will generate a short reset pulse of one CK cycle dura-
tion. On the falling edge of this pulse, the delay timer starts counting the Time-out period
t_TOUT. Refer to page 53 for details on operation of the Watchdog Timer.
Figure 28. Watchdog Reset During Operation
CC
CK
MCU Status Register –
MCUSR
The MCU Status Register provides information on which reset source caused an MCU
reset.
Bit
7
6
5
4
3
2
1
0
–
–
–
JTRF WDRF BORF EXTRF PORF MCUSR
Read/Write
R
R
R
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
See Bit Description
• Bit 7..5 – Reserved Bits
These bits are reserved for future use.
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4250E–CAN–12/04