cs5535 National Semiconductor Corporation, cs5535 Datasheet - Page 354

• Manufacturer Part Number: cs5535
• Description: Geode Cs5535 Companion Multi-function South Bridge
• Manufacturer: National Semiconductor Corporation

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SMB Controller Register Descriptions
5.11.1 SMB Native Registers
5.11.1.1
SMB I/O Offset
Type
Reset Value
5.11.1.2
SMB I/O Offset
Type
Reset Value
This is a read/write register with a special clear. Some of its bits may be cleared by software, as described in the table
below. This register maintains the current SMB status. On reset, and when the SMB is disabled, SMBST is cleared (00h).
Bit
7:0
SLVSTP
Bit
7
6
7
7
SMB Serial Data (SMB_SDA)
SMB Status (SMB_STS)
Name
SMBSDA
Name
SLVSTP (R/W1C)
SDAST (RO)
SDAST
00h
R/W
00h
01h
R/W
00h
6
6
Description
SMB Serial Data. This shift register is used to transmit and receive data. The most sig-
nificant bit is transmitted (received) first, and the least significant bit is transmitted last.
Reading or writing to the SMBSDA register is allowed only when the SDAST bit (SMB
I/O Offset 01h[6]) is set, or for repeated starts after setting the START bit (SMB I/O Off-
set 03h[0]). Any attempt to access the register in other cases may produce unpredict-
able results.
Description
Slave Stop (Read/Write 1 to Clear). Writing 0 to SLVSTP is ignored.
0: Writing 1 or SMB disabled.
1: Stop condition detected after a slave transfer in which MATCH (SMB I/O Offset
SMB_DATA Status (Read Only).
0: Reading from SMBSDA (SMB I/O Offset 00h) during a receive, or when writing to it
1: SMBSDA awaiting data (transmit - master or slave) or holds data that should be
BER
02h[2]) or GCMATCH (SMB I/O Offset 02h[3]) was set.
during a transmit. When START (SMB I/O Offset 03h[0]) is set, reading SMBSDA
does not clear SDAST; enabling the SMB to send a repeated start in master receive
mode.
read (receive - master or slave).
5
5
SMB_SDA Bit Descriptions
SMB_STS Bit Descriptions
SMB_SDA Register Map
SMB_STS Register Map
NEGACK
4
4
(Continued)
SMBSDA
354
STASTR
3
3
NMATCH
2
2
MASTER
1
1
XMIT
Revision 0.8
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