at91sam9g20-cu ATMEL Corporation, at91sam9g20-cu Datasheet - Page 92

• Manufacturer Part Number: at91sam9g20-cu
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

Figure 14-8. Watchdog Reset
14.3.5
92
WDRPROC = 0
AT91SAM9G20 Preliminary
Reset State Priorities
Only if
periph_nreset
proc_nreset
When the WDRSTEN in WDT_MR bit is reset, the watchdog fault has no impact on the reset
controller.
The Reset State Manager manages the following priorities between the different reset sources,
given in descending order:
Particular cases are listed below:
(nrst_out)
• Backup Reset
• Wake-up Reset
• Watchdog Reset
• Software Reset
• User Reset
• When in User Reset:
• When in Software Reset:
• When in Watchdog Reset:
RSTTYP
wd_fault
NRST
SLCK
MCK
– A watchdog event is impossible because the Watchdog Timer is being reset by the
– A software reset is impossible, since the processor reset is being activated.
– A watchdog event has priority over the current state.
– The NRST has no effect.
– The processor reset is active and so a Software Reset cannot be programmed.
– A User Reset cannot be entered.
proc_nreset signal.
Freq.
Any
Any
Processor Startup
= 3 cycles
XXX
EXTERNAL RESET LENGTH
8 cycles (ERSTL=2)
0x2 = Watchdog Reset
6384B–ATARM–15-Dec-08