PC87351 datasheet(45/86 Pages) NSC

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2.0 Device Architecture and Configuration (Continued)

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2.11.2

Configuration

2.11.3

KBC Configuration Register

This register is reset by hardware to 40h.

Location:

Index F0h

Type:

R/W

Usage Hints: When required to change the clock frequency of the KBC, perform the following:

1. Disable the KBC logical device.

2. Change the frequency setting.

3. Enable the KBC logical device.

Index

Mouse Conﬁguration Register or Action

Type

Reset

30h

Activate. See also bit 0 of the SIOCF1. When the Mouse of the KBC is inactive, the

IRQ selected by the Mouse Interrupt Number Register (index 70h) is not asserted.

This register has no effect on host KBC commands handling the PS/2 Mouse.

R/W

00h

70h

Mouse Interrupt Number

R/W

0Ch

71h

Mouse Interrupt Type. Bits 1,0 are read/write; other bits are read only.

R/W

02h

74h

Report no DMA assignment

04h

75h

Report no DMA assignment

04h

Index

Keyboard Conﬁguration Register or Action

Type

Reset

30h

Activate. See also bit 0 of the SIOCF1.

R/W

01h

60h

Base Address MSB Register. Bits 7-3 (for A15-11) are read only, 00000b.

R/W

00h

61h

Base Address LSB Register. Bits 2-0 are read only 000b.

R/W

60h

62h

Command Base Address MSB Register. Bits 7-3 (for A15-11) are read only, 00000b.

R/W

00h

63h

Command Base Address LSB. Bits 2-0 are read only 100b.

R/W

64h

70h

KBC Interrupt Number

R/W

01h

71h

KBC Interrupt Type. Bits 1,0 are read/write; others are read only.

R/W

02h

74h

Report no DMA assignment

04h

75h

Report no DMA assignment

04h

F0h

KBC Conﬁguration Register

R/W

40h

Bit

76543210

Name

KBC Clock Source

Reserved

TRI-STATE

Control

Reset

01000000

Required

Bit

Description

7-6

KBC Clock Source. The clock source can be changed only when the KBC is inactive (disabled).

Bits

7 6

Function

0 0

8 MHz

0 1

12 MHz (default)

1 0

16 MHz

1 1

Reserved

5-1

Reserved. Use read-modify-write to change the value of the register. Do not change the value of these bits. Bit

2 must be 0.

TRI-STATE Control. If KBC is inactive (disabled) when this bit is set, the KBC pins (KBCLK and KBDAT) are in TRI-

STATE. If Mouse is inactive (disabled) when this bit is set, the Mouse pins (MCLK and MDAT) are in TRI-STATE.

0: Disabled (default)

1: Enabled when device inactive

PC87351 Datasheet(PDF) 45 Page - National Semiconductor (TI)

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