82801DB Datasheet, PDF (194/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

Functional Description
Table 5-75. USB Legacy Keyboard State Transitions
Current State Action Data Value Next State
Comment
IDLE
IDLE
IDLE
IDLE
IDLE
GateState1
GateState1
GateState1
GateState1
GateState1
GateState2
GateState2
GateState2
GateState2
GateState2
64h / Write
64h / Write
64h / Read
60h / Write
60h / Read
60h / Write
64h / Write
64h / Write
60h / Read
64h / Read
64 / Write
64h / Write
64h / Read
60h / Write
60h / Read
D1h
Not D1h
N/A
Don't Care
N/A
XXh
D1h
Not D1h
N/A
N/A
FFh
Not FFh
N/A
XXh
N/A
GateState1
IDLE
IDLE
IDLE
IDLE
GateState2
GateState1
ILDE
IDLE
GateState1
IDLE
IDLE
GateState2
IDLE
IDLE
Standard D1 command. Cycle passed through to
8042. SMI# doesn't go active. PSTATE (offset C0,
bit 6) goes to 1.
Bit 3 in configuration register determines if cycle
passed through to 8042 and if SMI# generated.
Bit 2 in configuration register determines if cycle
passed through to 8042 and if SMI# generated.
Bit 1 in configuration register determines if cycle
passed through to 8042 and if SMI# generated.
Bit 0 in configuration register determines if cycle
passed through to 8042 and if SMI# generated.
Cycle passed through to 8042, even if trap enabled
in Bit 1 in configuration register. No SMI#
generated. PSTATE remains 1. If data value is not
DFh or DDh, then the 8042 may chose to ignore it.
Cycle passed through to 8042, even if trap enabled
via Bit 3 in configuration register. No SMI#
generated. PSTATE remains 1. Stay in GateState1
because this is part of the double-trigger
sequence.
Bit 3 in configuration space determines if cycle
passed through to 8042 and if SMI# generated.
PSTATE goes to 0. If Bit 7 in Configuration register
is set, then SMI# should be generated.
This is an invalid sequence. Bit 0 in configuration
register determines if cycle passed through to 8042
and if SMI# generated. PSTATE goes to 0. If Bit 7
in configuration register is set, then SMI# should be
generated.
Just stay in same state. Generate an SMI# if
enabled in Bit 2 of configuration register. PSTATE
remains 1.
Standard end of sequence. Cycle passed through
to 8042. PSTATE goes to 0. Bit 7 in configuration
space determines if SMI# should be generated.
Improper end of sequence. Bit 3 in the
configuration register determines if cycle passed
through to 8042 and if SMI# generated. PSTATE
goes to 0. If Bit 7 in the configuration register is set,
then SMI# should be generated.
Just stay in same state. Generate an SMI# if
enabled in Bit 2 of configuration register. PSTATE
remains 1.
Improper end of sequence. Bit 1 in the
configuration register determines if cycle passed
through to 8042 and if SMI# generated. PSTATE
goes to 0. If Bit 7 in configuration register is set,
then SMI# should be generated.
Improper end of sequence. Bit 0 in the
configuration register determines if cycle passed
through to 8042 and if SMI# generated. PSTATE
goes to 0. If Bit 7 in configuration register is set,
then SMI# should be generated.
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Intel^® 82801DB ICH4 Datasheet