LM3S9B90 Datasheet, PDF (209/1185 Pages) Texas Instruments – Stellaris® LM3S9B90 Microcontroller

Stellaris® LM3S9B90 Microcontroller
7.3.6
7.3.7
7.3.8
7.3.9
Power Control Using HIB
Important: The Hibernation Module requires special system implementation considerations when
using HIB to control power, as it is intended to power-down all other sections of the
microcontroller. All system signals and power supplies that connect to the chip must
be driven to 0 V_DC or powered down with the same regulator controlled by HIB. See
“Hibernation Module” on page 1120 for more details.
The Hibernation module controls power to the microcontroller through the use of the HIB pin which
is intended to be connected to the enable signal of the external regulator(s) providing 3.3 V to the
microcontroller and other circuits. When the HIB signal is asserted by the Hibernation module, the
external regulator is turned off and no longer powers the microcontroller and any parts of the system
that are powered by the regulator. The Hibernation module remains powered from the V_BAT supply
(which could be a battery or an auxiliary power source) until a Wake event. Power to the
microcontroller is restored by deasserting the HIB signal, which causes the external regulator to
turn power back on to the chip.
Power Control Using VDD3ON Mode
The Hibernation module may also be configured to cut power to all internal modules. While in this
state, all pins are configured as inputs. In the VDD3ON mode, the regulator should maintain 3.3 V
power to the microcontroller during Hibernate. This power control mode is enabled by setting the
VDD3ON bit in HIBCTL.
Initiating Hibernate
Prior to initiating hibernation, a wake-up condition must be configured, either from the external WAKE
pin, or by using an RTC match. Hibernation mode is initiated when the HIBREQ bit of the HIBCTL
register is set. If a Flash memory write operation is in progress, an interlock feature holds off the
transition into Hibernation mode until the write has completed.
The Hibernation module is configured to wake from the external WAKE pin by setting the PINWEN
bit of the HIBCTL register. It is configured to wake from RTC match by setting the RTCWEN bit. Either
one or both of these bits must be set prior to going into hibernation. Note that the WAKE pin uses
the Hibernation module's internal power supply as the logic 1 reference.
Upon either external wake-up or RTC match, the Hibernation module delays coming out of hibernation
until V_DD is above the minimum specified voltage, see Table 26-2 on page 1111.
When the Hibernation module wakes, the microcontroller performs a normal power-on reset. 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 209) and by looking for state data in the non-volatile
memory (see “Non-Volatile Memory” on page 208).
Interrupts and Status
The Hibernation module can generate interrupts when the following conditions occur:
■ Assertion of WAKE pin
■ RTC match
■ Low battery detected
All of the interrupts are ORed together before being sent to the interrupt controller, so the Hibernate
module can only generate a single interrupt request to the controller at any given time. The software
June 14, 2010
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Texas Instruments-Advance Information