SAM3U Datasheet, PDF (40/59 Pages) ATMEL Corporation – AT91SAM ARM-based Flash MCU

10.7
Watchdog Timer
• 16-bit key-protected once-only Programmable Counter
• Windowed, prevents the processor to be in a dead-lock on the watchdog access
10.8
SysTick Timer
• 24-bit down counter
• Self-reload capability
• Flexible system timer
10.9
Real-time Timer
• Real-time Timer, allowing backup of time with different accuracies
– 32-bit Free-running back-up Counter
– Integrates a 16-bit programmable prescaler running on slow clock
– Alarm Register capable to generate a wake-up of the system
10.10 Real-time Clock
• Low power consumption
• Full asynchronous design
• Two hundred year calendar
• Programmable Periodic Interrupt
• Alarm and update parallel load
• Control of alarm and update Time/Calendar Data In
10.11 General-Purpose Back-up Registers
• Eight 32-bit general-purpose backup registers
10.12 Nested Vectored Interrupt Controller
• Thirty maskable interrupts
• Sixteen priority levels
• Dynamic reprioritization of interrupts
• Priority grouping
– selection of preempting interrupt levels and non preempting interrupt levels.
• Support for tail-chaining and late arrival of interrupts.
– back-to-back interrupt processing without the overhead of state saving and
restoration between interrupts.
• Processor state automatically saved on interrupt entry, and restored on
– interrupt exit, with no instruction overhead.
40 SAM3U Series
6430ES–ATARM–22-Aug-11