CS5535 datasheet(355/555 Pages) NSC

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SMB Controller Register Descriptions (Continued)

BER (R/W1C)

Bus Error (Read/Write 1 to Clear). Writing 0 to BER is ignored.

0: Writing 1 or SMB disabled.

1: Invalid Start or Stop condition detected during data transfer (i.e., Start or Stop condi-

tion during the transfer of bits [8:2] and acknowledge cycle), or when an arbitration

problem detected. If the SMBus loses an arbitration this bit is set.

NEGACK

(R/W1C)

Neg Acknowledge (Read/Write 1 to Clear). Writing 0 to NEGACK is ignored.

0: Writing 1 or SMB disabled.

1: Transmission not acknowledged on the ninth clock. (In this case, SDAST (bit 6) is

not set.)

STASTR (R/W1C)

Stall After Start (Read/Write 1 to Clear). Writing 0 to STASTR is ignored. When

STASTR is set, it stalls the SMBus by pulling down the SMB_CLK line, and suspends

any further action on the bus (e.g., receive of first byte in master receive mode).

0: Writing 1 or SMB disabled.

1: This bit is not set in the slave mode and is only set in the master transmit mode.

When set, this bit indicates that the address was sent successfully and the bus is

now stalled. Note that this mode of operation must be enabled with the STASTRE bit

(SMB I/O Offset 03h[7]) in order for this bit to function this way. Also, if enabled with

INTEN (SMB I/O Offset 03h[2]), an interrupt is sent when this bit is set. This bit is

cleared by writing a 1 to it; writing a 0 has no effect.

2NMATCH

(R/W1C)

New Match (Read/Write 1 to Clear). Writing 0 to NMATCH is ignored. If INTEN (SMB

I/O Offset 03h[2]) is set, an interrupt is sent when this bit is set.

0: Software writes 1 to this bit.

1: Address byte follows a Start condition or a Repeated Start, causing a match or a

global-call match.

1MASTER (RO)

Master (Read Only).

0: Arbitration loss (BER, bit 5, is set) or recognition of a Stop condition.

1: Bus master request succeeded and master mode active.

XMIT (RO)

Transmit (Read Only). Direction bit.

0: Master/slave transmit mode not active.

1: Master/slave transmit mode active.

SMB_STS Bit Descriptions (Continued)

Bit

Name

Description

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