Atmel Xplained Pro Evaluation Kit ATSAM4E-XPRO ATSAM4E-XPRO Data Sheet
Product codes
ATSAM4E-XPRO
SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
378
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 SUPC_SR is set and remains high until the register is read.
started and the FWUP bit in SUPC_SR is set and remains high until the register is read.
19.4.7.2 Wake-up Inputs
The wake-up inputs, WKUPx, 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, WKUPENx, in the Wake-up Inputs register (SUPC_WUIR). The
wake-up level can be selected with the corresponding polarity bit, WKUPTx, also located in SUPC_WUIR.
be enabled by writing to 1 the corresponding bit, WKUPENx, in the Wake-up Inputs register (SUPC_WUIR). The
wake-up level can be selected with the corresponding polarity bit, WKUPTx, also located in SUPC_WUIR.
All the resulting signals are wired-ORed to trigger a debounce counter, which is programmed with the WKUPDBC
field in SUPC_WUMR. The WKUPDBC field selects 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). Programming 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.
field in SUPC_WUMR. The WKUPDBC field selects 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). Programming 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
supply is started and the signals, WKUP0 to WKUP15 as shown in
, are latched in
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 primary information is lost. No new wake-up can be detected since the primary wake-up condition has
disappeared.
19.4.7.3 Low-power Tamper Detection and Anti-Tampering
Low-power debouncer inputs (WKUP0, WKUP1) can be used for tamper detection. If the tamper sensor is biased
through a resistor and constantly driven by the power supply, this leads to power consumption as long as the
tamper detection switch is in its active state. To prevent power consumption when the switch is in active state, the
tamper sensor circuitry must be intermittently powered, and thus a specific waveform must be applied to the
sensor circuitry.
through a resistor and constantly driven by the power supply, this leads to power consumption as long as the
tamper detection switch is in its active state. To prevent power consumption when the switch is in active state, the
tamper sensor circuitry must be intermittently powered, and thus a specific waveform must be applied to the
sensor circuitry.
The waveform is generated using RTCOUTx in all modes including backup mode. Refer to the RTC section for
waveform generation.
waveform generation.
Separate debouncers are embedded, one for WKUP0 input, one for WKUP1 input.
The WKUP0 and/or WKUP1 inputs perform a system wake-up upon tamper detection. This is enabled by setting
the LPDBCEN0/1 bit in the
the LPDBCEN0/1 bit in the
(SUPC_WUMR).
WKUP0 and/or WKUP1 inputs can also be used when VDDCORE is powered to detect a tamper.
When the bit LPDBCENx = 1, WKUPx pins must not be configured to act as a debouncing source for the
WKUPDBC counter (WKUPENx must be cleared in SUPC_WUIR).
WKUPDBC counter (WKUPENx must be cleared in SUPC_WUIR).
Low-power tamper detection or debounce requires RTC output (RTCOUTx) to be configured to generate a duty
cycle programmable pulse (i.e., OUT0 = 0x7 in RTC_MR) in order to create the sampling points of both
debouncers. The sampling point is the falling edge of the RTCOUTx waveform.
cycle programmable pulse (i.e., OUT0 = 0x7 in RTC_MR) in order to create the sampling points of both
debouncers. The sampling point is the falling edge of the RTCOUTx waveform.
shows an example of an application where two tamper switches are used. RTCOUTx powers the
external pull-up used by the tamper sensor circuitry.