307013-003 Datasheet, PDF (206/848 Pages) Intel Corporation – Intel I/O Controller Hub 7

Functional Description
Table 5-47. USB Legacy Keyboard State Transitions (Sheet 2 of 2)
Current
State
Action
Data
Value
Next
State
Comment
GateState1
GateState1
GateState1
GateState1
GateState2
GateState2
GateState2
GateState2
GateState2
64h / Write
64h / Write
60h / Read
64h / Read
64 / Write
64h / Write
64h / Read
60h / Write
60h / Read
D1h
Not D1h
N/A
N/A
FFh
Not FFh
N/A
XXh
N/A
GateState1
Cycle passed through to 8042, even if trap
enabled via Bit 3 in Config Register. No SMI#
generated. PSTATE remains 1. Stay in
GateState1 because this is part of the
double-trigger sequence.
ILDE
Bit 3 in Config space determines if cycle
passed through to 8042 and if SMI#
generated. PSTATE goes to 0. If Bit 7 in
Config Register is set, then SMI# should be
generated.
IDLE
This is an invalid sequence. Bit 0 in Config
Register determines if cycle passed through
to 8042 and if SMI# generated. PSTATE goes
to 0. If Bit 7 in Config Register is set, then
SMI# should be generated.
Just stay in same state. Generate an SMI# if
GateState1 enabled in Bit 2 of Config Register. PSTATE
remains 1.
IDLE
Standard end of sequence. Cycle passed
through to 8042. PSTATE goes to 0. Bit 7 in
Config Space determines if SMI# should be
generated.
IDLE
Improper end of sequence. Bit 3 in Config
Register determines if cycle passed through
to 8042 and if SMI# generated. PSTATE goes
to 0. If Bit 7 in Config Register is set, then
SMI# should be generated.
Just stay in same state. Generate an SMI# if
GateState2 enabled in Bit 2 of Config Register. PSTATE
remains 1.
IDLE
Improper end of sequence. Bit 1 in Config
Register determines if cycle passed through
to 8042 and if SMI# generated. PSTATE goes
to 0. If Bit 7 in Config Register is set, then
SMI# should be generated.
IDLE
Improper end of sequence. Bit 0 in Config
Register determines if cycle passed through
to 8042 and if SMI# generated. PSTATE goes
to 0. If Bit 7 in Config Register is set, then
SMI# should be generated.
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Intel ^® ICH7 Family Datasheet