Hibernation Module
11 Hibernation Module
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
11.1 Introduction
The Hibernate API provides a set of functions for using the Hibernation module, which allows the
software application to cause power to be removed from the microcontroller, and then be powered
on later based on specific time or a signal on the external WAKE pin. The API provides func-
tions to configure wake conditions, manage interrupts, read status, save and restore program state
information, and request hibernation mode.
Some of the features of the Hibernation module are:
32-bit real time clock
Trim register for fine tuning the RTC rate
Two RTC match registers for generating RTC events
External WAKE pin to initiate a wake-up
Low-battery detection
64 32-bit words of non-volatile memory
Programmable interrupts for hibernation events
The Hibernation module must be enabled before it can be used. Use the
ROM_HibernateEnableExpClk() function to enable it. If a crystal is used for the clock
source, then the initializing code must allow time for the crystal to stabilize after calling the
ROM_HibernateEnableExpClk() function. Refer to the device data sheet for information about
crystal stabilization time. If an oscillator is used, then no delay is necessary.
In order to use the RTC feature of the Hibernation module, the RTC must be enabled by calling
ROM_HibernateRTCEnable(). It can be later disabled by calling ROM_HibernateRTCDisable().
These functions can be called at any time to start and stop the RTC. The RTC value can be read or
set by using the ROM_HibernateRTCGet() and ROM_HibernateRTCSet() functions. The real-time
clock rate can be adjusted by using the trim register. Use the ROM_HibernateRTCTrimGet() and
ROM_HibernateRTCTrimSet() functions for this purpose.
Application state information can be stored in the non-volatile memory of the Hiberna-
tion module when the processor is powered off. Use the ROM_HibernateDataSet() and
ROM_HibernateDataGet() functions to access the non-volatile memory area.
The module can be configured to wake when the external WAKE pin is asserted, or when an
RTC match occurs, or both. Use the ROM_HibernateWakeSet() function to configure the wake
conditions. The present configuration can be read by calling ROM_HibernateWakeGet().
The Hibernation module can detect a low battery and signal the processor. It can also be configured
to abort a hibernation request if the battery voltage is too low. Use the ROM_HibernateLowBatSet()
and ROM_HibernateLowBatGet() functions to configure this feature.
Several functions are provided for managing interrupts. Use the ROM_HibernateIntEnable() and
ROM_HibernateIntDisable() functions to enable and disable specific interrupt sources. The present
April 8, 2013 107
To Next Page
Loading...
Need help?
General
