7.3.9
Power Control Using VDD3ON Mode
The Hibernation module may also be configured to cut power to all internal modules during Hibernate
mode. While in this state, if
VDD3ON
is set in the
HIBCTL
register, all pins are held in the state they
were in prior to entering hibernation. For example, inputs remain inputs; outputs driven high remain
driven high, and so on. There are important procedural and functional items to note when in VDD3ON
mode:
■ JTAG Ports C[0] - C[3] do not retain their state in Hibernate VDD3ON mode.
■ If GPIO pins K[7:4] are not used as a wake source, they should not be left floating. An internal
pull-up resistor may be configured by the application before entering Hibernate mode by
programming the
GPIO Pull-Up Select (GPIOPUR)
register in the GPIO module.
■ In the VDD3ON mode, the regulator should maintain 3.3 V power to the microcontroller during
Hibernate. GPIO retention is disabled when the
RETCLR
bit is cleared in the
HIBCTL
register.
■ When entering hibernation in VDD3ON mode, the supply rails to the Ethernet resistors R1, R2,
R3, R4 found in Figure 20-13 on page 1464 must be switched off.
7.3.10
Initiating Hibernate
Hibernate mode is initiated when the
HIBREQ
bit of the
HIBCTL
register is set. If a wake-up condition
has not been configured using the
PINWEN
or
RTCWEN
bits in the
HIBCTL
register, the hibernation
request is ignored. In addition, if the battery voltage is below the threshold voltage defined by the
VBATSEL
field in the
HIBCTL
register, the hibernation request is ignored.
7.3.11
Waking from Hibernate
The Hibernation module can be configured to wake from Hibernate mode if any of the following are
enabled:
■ External
WAKE
■ External
RST
■ GPIO K[7:4]
■ Tamper
TMPR[3:0]
■ Tamper XOSC failure
The Hibernation module can also be configured to wake from hibernate when the following events
occur:
■ RTC match wake event
■ Low Battery wake event
The external
WAKE
pin is enabled by setting the
PINWEN
bit in the
HIBCTL
register. The external
WAKE
pin can generate an interrupt by programming the
EXTWEN
bit in the
Hibernation Interrupt
Mask (HIBIM)
register.
Note:
If an external
WAKE
signal is asserted, the application is responsible for clearing the signal
source once the
EXTWEN
bit has been registered in the
Hibernation Raw Interrupt Status
(HIBRIS)
register.
June 18, 2014
546
Texas Instruments-Production Data
Hibernation Module