GXLV Datasheet, PDF (179/247 Pages) National Semiconductor (TI) – Geode™ GXLV Processor Series Low Power Integrated x86 Solutions

Power Management (Continued)
5.2.2 Initiating Suspend with SUSP#
The GXLV processor enters the Suspend mode in
response to SUSP# input assertion only when certain
conditions are met. First, the USE_SUSP bit must be set
in CCR2 (Index C2h[7]). In addition, execution of the cur-
rent instructions and any pending decoded instructions
and associated bus cycles must be completed. SUSP# is
sampled on the rising edge of SYSCLK, and must meet
specified setup and hold times to be recognized at a par-
ticular SYSCLK edge. See Figure 5-2 for timing details.
When all conditions are met, the SUSPA# output is
asserted. The time from assertion of SUSP# to the activa-
tion of SUSPA# depends on which instructions were
decoded prior to assertion of SUSP#. Normally, once
SUSP# has been sampled inactive the SUSPA# output
will be deactivated within two clocks. However, the deacti-
vation of SUSPA# may be delayed until the end of an
active refresh cycle.
If the CPU is already in a Suspend mode initiated by
SUSP#, one occurrence of INTR and SMI# is stored for
execution after Suspend mode is exited. The CPU also
allows PCI master accesses during a SUSP#-initiated
Suspend mode. See Figure 5-3 for timing details. If an
unmasked REQx# is asserted, the GXLV processor will
deassert SUSPA# and exit Suspend mode to respond to
the PCI master access. If SUSP# is asserted when the
PCI master access is completed, REQx# deasserted, the
GXLV processor will reassert SUSPA# and return to a
SUSP#-initiated Suspend mode. If the CPU is in the mid-
dle of a PCI master access when SUSP# is asserted, the
assertion of SUSPA# will be delayed until the PCI access
is completed.
SYSCLK
SUSP#
SUSPA#
Figure 5-2. SUSP#-Initiated Suspend Mode
SYSCLK
REQx#
FRAME#
TRDY#
SUSP#
SUSPA#
Revision 1.1
Figure 5-3. PCI Access During Suspend Mode
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