AT32UC3C1512C Automotive Atmel Corporation, AT32UC3C1512C Automotive Datasheet - Page 54

• Manufacturer Part Number: AT32UC3C1512C Automotive
• Manufacturer: Atmel Corporation

7.6.3.4
7.6.4
7.6.5
9166C–AVR-08/11
Divided PB Clocks
Reset Controller
Precautions when entering sleep mode
Table 7-3.
1.
2.
Modules communicating with external circuits should normally be disabled before entering a
sleep mode that will stop the module operation. This prevents erratic behavior when entering or
exiting sleep mode. Please refer to the relevant module documentation for recommended
actions.
Communication between the synchronous clock domains is disturbed when entering and exiting
sleep modes. This means that bus transactions are not allowed between clock domains affected
by the sleep mode. The system may hang if the bus clocks are stopped in the middle of a bus
transaction.
The CPU is automatically stopped in a safe state to ensure that all CPU bus operations are com-
plete when the sleep mode goes into effect. Thus, when entering Idle mode, no further action is
necessary.
When entering a sleep mode (except Idle mode), all HSB masters must be stopped before
entering the sleep mode. Also, if there is a chance that any PB write operations are incomplete,
the CPU should perform a read operation from any register on the PB bus before executing the
sleep instruction. This will stall the CPU while waiting for any pending PB operations to
complete.
The clock generator in the Power Manager provides divided PBx clocks for use by peripherals
that require a prescaled PBx clock. This is described in the documentation for the relevant
modules.
The divided clocks are directly maskable, and are stopped in sleep modes where the PBx clocks
are stopped.
The Reset Controller collects the various reset sources in the system and generates hard and
soft resets for the digital logic.
The device contains a Power-On Detector, which keeps the system reset until power is stable.
This eliminates the need for external reset circuitry to guarantee stable operation when powering
up the device.
It is also possible to reset the device by asserting the RESET_N pin. This pin has an internal
pull-up, and does not need to be driven externally when negated.
these and other reset sources supported by the Reset Controller.
Index
3
4
5
(1)
Only PB modules, as HSB modules have stopped clock.
WDT only if clocked from 32 KHz oscillator.
Sleep Mode
Stop
DeepStop
Static
Wake up sources
Wake up Sources
Asynchronous
Asynchronous
Asynchronous
(2)
Table 7-4 on page 55
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