SCH3112 Datasheet, PDF(195/396 Page) SMSC Corporation – LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports

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SCH3112 Datasheet, PDF (195/396 Pages) SMSC Corporation – LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports

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LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports

Datasheet

Option 1 (00): De-assert KB_PB_STS 0.5sec after it is asserted.

This option allows the user to program any scan code into the Keyboard Scan Code â Make Byte

Register(s). When a valid scan code is received that matches the value programmed in the Keyboard

Scan Code Register(s), a 0.5sec pulse is generated on the KB_PB_STS wake event. Regardless of

the state of the SPEKEY bits in PME_STS1 and PME_STS1, no additional wake events will no

additional wake events will occur for 0.5sec.

Keyboard Input

Valid Scan Code

(1 or 2 bytes)

Scan Code

KB_PB_STS

Pulse Width=0.5sec

Figure 20.8 Option 1: KB_PB_STS wake event fixed pulse width

Option 2 (01): De-assert KB_PB_STS after Scan Code Not Equal Programmed Make Code

This option may be used by keyboards that emit single byte or multi-byte make codes for each key

pressed. When a valid Scan Code is received that matches the value programmed in the Keyboard

Scan Code â Make Byte Register(s), the KB_PB_STS wake event signal will be held asserted low until

another valid Scan Code is received that is not equal to the programmed make code. Regardless of

the state of the SPEKEY bits in PME_STS1 and PME_STS1, no additional wake events will no

additional wake events will occur until another valid Scan Code is received that is not equal to the

programmed make code.

Keyboard Input

KB_PB_STS

Valid Scan Code=

Programmed Make

Code

Invalid Scan Code

Valid Scan Code Not =

Programmed Make Code

Pulse Width

Figure 20.9 Option 2: Assert KB_PB_STS wake event until scan code not programmed make code

Notes:

â The Valid Scan Code may be 1 or 2 bytes depending on the SPEKEY ScanCode bits located in

the PME_STS1 Runtime register at offset 64h.

â A Valid Scan Code for single byte codes means that no parity error exists. A Valid Scan Code for

Multi-byte Scan Codes requires that no parity error exists and that the first Byte received matches

the value programmed in the Keyboard Scan Code â Make Byte 1 located in the Runtime Register

block at offset 5Fh. This value is typically E0h for Scan 1 and Scan 2 type keyboards. (Example:

The ACPI power scan 2 make code is E0h, 37h) Section 20.5.1.2, "Description Of SCAN 1 and

SCAN 2," on page 177

Option 3 (10): De-assert KB_PB_STS after Scan Code Equal Break Code

This option may be used with single byte and multi-byte scan 1 and scan 2 type keyboards. The break

code can be configured for a specific break code or for any valid break code.

the KB_PB_STS wake event signal will be held asserted low until a valid break code is detected. The

break code can be configured for a specific break code or for any valid break code. Regardless of the

SMSC SCH311X

179

DATASHEET

Rev 0.2 (09-28-04)

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