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Functional Description
490
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Hibernation Module
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.
If V
DD
is arbitrarily removed while a Flash memory or HIBDATA register write operation is in progress, the
write operation must be retried after V
DD
is reapplied.
6.3.13 Interrupts and Status
The Hibernation module can generate interrupts when the following conditions occur:
•
Assertion of WAKE pin
•
RTC match
•
Low battery detected
•
Write complete/capable
•
Assertion of an external RESET pin
•
Assertion of an external wake-enabled GPIO pin (port K[7:4] ])
All of the interrupts except for the tamper signals 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 interrupt handler can service multiple interrupt events by reading the Hibernation
Masked Interrupt Status (HIBMIS) register. Software can also read the status of the Hibernation module at
any time by reading the HIBRIS register which shows all of the pending events. This register can be used
after waking from hibernation to see if a wake condition was caused by one of the events above or by a
power loss.
The WAKE pin can generate interrupts in Run, Sleep and Deep Sleep Mode. The events that can trigger
an interrupt are configured by setting the appropriate bits in the Hibernation Interrupt Mask (HIBIM)
register. Pending interrupts can be cleared by writing the corresponding bit in the Hibernation Interrupt
Clear (HIBIC) register.
6.4
Initialization and Configuration
The Hibernation module has several different configurations. The following sections show the
recommended programming sequence for various scenarios. Because the Hibernation module runs at a
low frequency and is asynchronous to the rest of the microcontroller, which is run off the system clock,
software must allow a delay of t
HIB_REG_ACCESS
after writes to registers (see
). The WC interrupt
in the HIBMIS register can be used to notify the application when the Hibernation modules registers can
be accessed.
6.4.1 Initialization
The Hibernation module comes out of reset with the system clock enabled to the module, but if the system
clock to the module has been disabled, then it must be re-enabled, even if the RTC feature is not used.
See
.
If a 32.768-kHz crystal is used as the Hibernation module clock source, perform the following steps:
1. Write 0x0000.0010 to the HIBIM register to enable the WC interrupt.
2. Write 0x40 to the HIBCTL register at offset 0x10 to enable the oscillator input.
3. Wait until the WC interrupt in the HIBMIS register has been triggered before performing any other
operations with the Hibernation module.
If a 32.768-kHz single-ended oscillator is used as the Hibernation module clock source, then perform the
following steps:
1. Write 0x0000.0010 to the HIBIM register to enable the WC interrupt.
2. Write 0x0001.0040 to the HIBCTL register at offset 0x10 to enable the oscillator input and bypass the
on-chip oscillator.
3. Wait until the WC interrupt in the HIBMIS register has been triggered before performing any other
operations with the Hibernation module.