SAM3X8E Atmel Corporation, SAM3X8E Datasheet - Page 283

• Manufacturer Part Number: SAM3X8E
• Manufacturer: Atmel Corporation

17.4.8.1
17.4.8.2
17.4.8.3
17.4.8.4
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12
Force Wake Up
Wake Up Inputs
Clock Alarms
Supply Monitor Detection
The FWUP pin is enabled as a wake up source by writing the FWUPEN bit to 1 in the Supply
Controller Wake Up Mode Register (SUPC_WUMR). Then, the FWUPDBC field in the same
register selects the debouncing period, which can be selected between 3, 32, 512, 4,096 or
32,768 slow clock cycles. This corresponds respectively to about 100 μs, about 1 ms, about 16
ms, about 128 ms and about 1 second (for a typical slow clock frequency of 32 kHz). Program-
ming FWUPDBC to 0x0 selects an immediate wake up, i.e., the FWUP must be low during a
minimum of one slow clock period to wake up the core power supply.
If the FWUP pin is asserted for a time longer than the debouncing period, a wake up of the core
power supply is started and the FWUP bit in the Supply Controller Status Register (SUPC_SR)
is set and remains high until the register is read.
The wake up inputs, WKUP0 to WKUP15, can be programmed to perform a wake up of the core
power supply. Each input can be enabled by writing to 1 the corresponding bit, WKUPEN0 to
WKUPEN 15, in the Wake Up Inputs Register (SUPC_WUIR). The wake up level can be
selected with the corresponding polarity bit, WKUPPL0 to WKUPPL15, also located in
SUPC_WUIR.
All the resulting signals are wired-ORed to trigger a debounce counter, which can be pro-
grammed with the WKUPDBC field in the Supply Controller Wake Up Mode Register
(SUPC_WUMR). The WKUPDBC field can select a debouncing period of 3, 32, 512, 4,096 or
32,768 slow clock cycles. This corresponds respectively to about 100 μs, about 1 ms, about
16 ms, about 128 ms and about 1 second (for a typical slow clock frequency of 32 kHz). Pro-
gramming WKUPDBC to 0x0 selects an immediate wake up, i.e., an enabled WKUP pin must be
active according to its polarity during a minimum of one slow clock period to wake up the core
power supply.
If an enabled WKUP pin is asserted for a time longer than the debouncing period, a wake up of
the core power supply is started and the signals, WKUP0 to WKUP15 as shown in
are latched in the Supply Controller Status Register (SUPC_SR). This allows the user to identify
the source of the wake up, however, if a new wake up condition occurs, the primary information
is lost. No new wake up can be detected since the primary wake up condition has disappeared.
The RTC and the RTT alarms can generate a wake up of the core power supply. This can be
enabled by writing respectively, the bits RTCEN and RTTEN to 1 in the Supply Controller Wake
Up Mode Register (SUPC_WUMR).
The Supply Controller does not provide any status as the information is available in the User
Interface of either the Real Time Timer or the Real Time Clock.
The supply monitor can generate a wakeup of the core power supply. See
ply
Monitor”.
Section 17.4.5 ”Sup-
SAM3X/A
SAM3X/A
Figure
17-7,
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