TM4C129ENCZAD Datasheet, PDF (558/2037 Pages) Texas Instruments – Tiva Microcontroller

Hibernation Module
7.3.12
To use the RST pin as a wake source, the WURSTEN bit must be set in the Hibernate I/O
Configuration (HIBIO) register and the WUUNLK bit must be set in the same register.
To enable any of the assigned GPIO pins as a wake source, the WUUNLK bit must be set in the
HIBIO register and the wake configuration must be programmed through the GPIOWAKEPEN and
GPIOWAKELVL registers in the GPIO module. Please refer to “General-Purpose Input/Outputs
(GPIOs)” on page 753 for more information on programming the GPIOs.
Note: The RST pin and GPIO wake sources are cleared by a write to either or both the RSTWK
and PADIOWK bits. This clears the source of interrupts for RSTWK, PADIOWK and the
GPIOWAKESTAT register.
TMPR[3:0] are enabled by setting the appropriate ENn bits the Tamper IO Control and Status
(HIBTPIO) register. The HIBTPIO register overrides the GPIO port configuration registers. By setting
the WAKE bit in the Tamper Control (HIBTPCTL) register, a tamper event can cause a wake from
Hibernate. If a tamper event occurs, the time of the event and the status of the tamper pins are
logged in the Tamper Log (HIBTPLOG) register.
By setting the RTCWEN bit in the HIBCTL register a wake from hibernate can occur when the value
of the HIBRTCC register matches the value of the HIBRTCM0 register and the value of the RTCSSC
field matches the RTCSSM field in the HIBRTCSS register.
To allow a wake from Hibernate on a low battery event, the BATWKEN bit in the HIBCTL register
must be set. In this configuration, the battery voltage is checked every 512 seconds while in
hibernation. If the voltage is below the level specified by the VBATSEL field, the LOWBAT interrupt
is set in the HIBRIS register.
Upon external wake-up, external reset, tamper event, or RTC match, the Hibernation module delays
coming out of hibernation until V_DD is above the minimum specified voltage, see Table
30-6 on page 1967.
When the Hibernation module wakes, the microcontroller performs a normal power-on reset. The
normal power-on reset does not reset the Hibernation module or Tamper module, but does reset
the rest of the microcontroller. Software can detect that the power-on was due to a wake from
hibernation by examining the raw interrupt status register (see “Interrupts and Status” on page 559)
and by looking for state data in the battery-backed memory (see “Battery-Backed
Memory” on page 556).
Arbitrary Power Removal
The microcontroller goes into hibernation if V_DD is arbitrarily removed when the CLK32EN bit is set
and any of the following bits are set:
■ TPEN bit in the HIBTPCTL register
■ PINWEN bit in the HIBCTL register
■ RTCEN bit in the HIBCTL register
The microcontroller wakes from hibernation when power is reapplied.
If the CLK32EN bit is set but the TPEN, PINWEN, and RTCEN bits are all clear, the microcontroller
still goes into hibernation if power is removed; however, when V_DD is reapplied, the MCU executes
a cold POR and the Hibernation module is reset. If the CLK32EN bit is not set and V_DD is arbitrarily
removed, the part is simply powered off and executes a cold POR when power is reapplied.
558
June 18, 2014
Texas Instruments-Production Data