LM3S1958 Datasheet, PDF (107/435 Pages) List of Unclassifed Manufacturers – Microcontroller

LM3S1958 Microcontroller
7.1 Block Diagram
Figure 7-1. Hibernation Module Block Diagram
XOSC0
XOSC1
WAKE
HIBCTL.CLK32EN
/128
HIBCTL.CLKSEL
Non-Volatile
Memory
HIBDATA
Pre-Divider
HIBRTCT
RTC
HIBRTCC
HIBRTCLD
HIBRTCM0
HIBRTCM1
Interrupts
HIBIM
HIBRIS
HIBMIS
HIBIC
MATCH0/1
LOWBAT
VDD
VBAT
Low Battery
Detect
Power
Sequence
Logic
HIBCTL.LOWBATEN
HIBCTL.PWRCUT
HIBCTL.RTCWEN
HIBCTL.EXTWEN
HIBCTL.VABORT
Interrupts
to CPU
HIB
7.2
7.2.1
Functional Description
The Hibernation module controls the power to the processor with an enable signal (HIB) that signals
an external voltage regulator to turn off. The Hibernation module itself is powered from a separate
supply such as a battery or auxillary supply. It also has a separate clock source to maintain a
real-time clock (RTC). Once in hibernation, the module signals an external voltage regulator to turn
back on the power when an external pin (WAKE) is asserted, or when the internal RTC reaches a
certain value. The Hibernation module can also detect when the battery voltage is low, and optionally
prevent hibernation when this occurs.
Power-up from a power cut to code execution is defined as the regulator turn-on time (specifed at
250 μs maximum) plus the normal chip POR (see Figure 19-11 on page 413).
Register Access Timing
Because the Hibernation module has an independent clocking domain, certain registers must be
written only with a timing gap between accesses. The delay time is t_{HIB_REG_WRITE}, therefore software
must guarantee that a delay of t_{HIB_REG_WRITE} is inserted between back-to-back writes to certain
Hibernation registers, or between a write followed by a read to those same registers. There is no
restriction on timing for back-to-back reads from the Hibernation module. Refer to “Register
Descriptions” on page 111 for details about which registers are subject to this timing restriction.
June 14, 2007
107
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