GXM Datasheet, PDF (25/244 Pages) National Semiconductor (TI) – Geode™ GXm Processor Integrated x86 Solution with MMX Support

Signal Definitions (Continued)
2.2.1 System Interface Signals (Continued)
Signal Name
BGA SPGA
Pin No. Pin No. Type
INTR
B18
D24
I
IRQ13
C22
C31
O
SMI#
SUSP#
C19
B28
I
H2
M4
I
(PU)
(PU)
SUSPA#
E2
H4
O
SERIALP
L3
Q1
O
Description
(Maskable) Interrupt Request
INTR is a level-sensitive input that causes the GXm processor to
Suspend execution of the current instruction stream and begin
execution of an interrupt service routine. The INTR input can be
masked through the Flags Register IF bit. (See Table 3-4 on
page 43 for bit definitions.)
Interrupt Request Level 13
IRQ13 is asserted if an on-chip floating point error occurs.
When a floating point error occurs, the GXm processor asserts
the IRQ13 pin. The floating point interrupt handler then performs
an OUT instruction to I/O address F0h or F1h. The GXm proces-
sor accepts either of these cycles and clears the IRQ13 pin.
Refer to Section 3.4.1 “I/O Address Space” on page 60 for fur-
ther information on IN/OUT instructions.
System Management Interrupt
SMI# is a level-sensitive interrupt. SMI# puts the GXm processor
into System Management Mode (SMM).
Suspend Request
This signal is used to request that the GXm processor enter Sus-
pend mode. After recognition of an active SUSP# input, the pro-
cessor completes execution of the current instruction, any
pending decoded instructions and associated bus cycles.
SUSP# is ignored following RESET# and is enabled by setting
the SUSP bit in CCR2. (See Table 16 on page 44 for CCR2 bit
definitions.)
Since the GXm processor includes system logic functions as well
as the CPU core, there are special modes designed to support
the different power management states associated with APM,
ACPI, and portable designs. The part can be configured to stop
only the CPU core clocks, or all clocks. When all clocks are
stopped, the external clock can also be stopped. (See Section
6.0 “Power Management” on page 174 for more details regarding
power management states.)
This pin is internally connected to a 20-kohm pull-up resistor.
SUSP# is pulled up when not active.
Suspend Acknowledge
Suspend Acknowledge indicates that the GXm processor has
entered low-power Suspend mode as a result of SUSP# asser-
tion or execution of a HALT instruction. SUSPA# is enabled by
setting the SUSP bit in CCR2. (See Table 16 on page 44 for
CCR2 bit definitions.)
The SYSCLK input may be stopped after SUSPA# has been
asserted to further reduce power consumption if the system is
configured for 3V Suspend mode. (Section 6.4 “3-Volt Suspend
Mode” on page 174 for details regarding this mode.)
Serial Packet
Serial Packet is the single wire serial-transmission signal to the
CS5530 chip. The clock used for this interface is the PCI clock
(SYSCLK). This interface carries packets of miscellaneous infor-
mation to the chipset to be used by the VSA software handlers.
Revision 3.1
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