539
SAM4CP [DATASHEET]
43051E–ATPL–08/14
A Fast Startup is enabled upon the detection of a programmed level on one of the 16 wake-up inputs (WKUP) or upon an
active alarm from the RTC and RTT. The polarity of the 16 wake-up inputs is programmable by writing the PMC Fast
Startup Polarity Register (PMC_FSPR).
The Fast Startup circuitry, as shown in
Figure 30-3
, is fully asynchronous and provides a fast startup signal to the Power
Management Controller. As soon as the fast startup signal is asserted, the embedded 4/8/12MHz Fast RC Oscillator
restarts automatically.
When entering Wait Mode, the embedded flash can be placed in one of the low-power modes (deep-power-down or
standby) depending on the configuration of the FLPM field in the PMC_FSMR. The FLPM field can be programmed at
anytime and its value will be applied to the next wait mode period.
The power consumption reduction is optimal when configuring 1 (deep power down mode) in field FLPM. If 0 is
programmed (standby mode), the power consumption is slightly higher than in deep-power- down mode.
When programming 2 in field FLPM, the Wait Mode flash power consumption is equivalent to that of the active mode
when there is no read access on the flash.
Figure 30-3.
Fast Startup Circuitry
Each wake-up input pin and alarm can be enabled to generate a Fast Startup event by setting the corresponding bit in
the PMC_FSMR.
The user interface does not provide any status for Fast Startup, but the user can easily recover this information by
reading the PIO Controller and the status registers of the RTC and RTT.
30.11 Main Processor Startup from Embedded Flash
The inherent start-up time of the embedded Flash cannot provide a fast startup of the system.
If system fast start-up time is not required, the first instruction after a wait mode exit can be located in the embedded
Flash. Under these conditions, prior to entering wait mode, the Flash controller must be programmed to perform access
in 0 wait-state (see Flash controller section).
fast_restart
WKUP15
FSTT15
FSTP15
WKUP1
FSTT1
FSTP1
WKUP0
FSTT0
FSTP0
RTTAL
RTCAL
RTT Alarm
RTC Alarm