SuperI/O Module

32579B

5.4.2.5LDN 05h and 06h - ACCESS.bus Ports 1 and 2

ACCESS.bus ports 1 and 2 (ACB1 and ACB2) are identi- cal. Each ACB is a two-wire synchronous serial interface compatible with the ACCESS.bus physical layer. ACB1 and ACB2 use a 24 MHz internal clock. Six runtime registers for each ACCESS.bus are described in Section 5.7 "ACCESS.bus Interface" on page 121.

ACB1 is designated as LDN 05h and ACB2 as LDN 06h. Table 5-13lists the configuration registers which affect the ACCESS.bus ports. Only the last register (F0h) is described here (Table 5-14). See Table 5-3 "Standard Con- figuration Registers" on page 95 for descriptions of the oth- ers.

Table 5-13. Relevant ACB1 and ACB2 Registers

 

 

 

Reset

Index

Type

Configuration Register or Action

Value

 

 

 

 

30h

R/W

Activate. See also bit 0 of the SIOCF1 register

00h

 

 

 

 

60h

R/W

Base Address MSB register.

00h

 

 

 

 

61h

R/W

Base Address LSB register. Bits [2:0] (for A[2:0]) are RO, 000b.

00h

 

 

 

 

70h

R/W

Interrupt Number.

00h

 

 

 

 

71h

R/W

Interrupt Type. Bit 1 is R/W. Other bits are RO.

03h

 

 

 

 

74h

RO

Report no DMA assignment.

04h

 

 

 

 

75h

RO

Report no DMA assignment.

04h

 

 

 

 

F0h

R/W

ACB1 and ACB2 Configuration register.

00h

 

 

 

 

Table 5-14. ACB1 and ACB2 Configuration Register

Bit

Description

Index F0h

ACB1 and ACB2 Configuration Register (R/W)

This register is reset by hardware to 00h.

7:3 Reserved.

2Internal Pull-Up Enable.

0:No internal pull-up resistors on AB1C/AB2C and AB1D/AB2D. (Default)

1:Internal pull-up resistors on AB1C/AB2C and AB1D/AB2D.

1:0

Reserved.

AMD Geode™ SC1200/SC1201 Processor Data Book

103

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AMD SC1201 Relevant ACB1 and ACB2 Registers, ACB1 and ACB2 Configuration Register, LDN 05h and 06h ACCESS.bus Ports 1