CS5535 datasheet(357/555 Pages) NSC

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SMB Controller Register Descriptions (Continued)

5.11.1.4

SMB Control 1 (SMB_CTRL1)

This register configures and controls the SMB functional block. It maintains the current SMB status and controls several

SMB functions. On reset and when the SMB is disabled, the non-reserved bits of SMB_CTRL1 are cleared.

SMB I/O Offset

03h

Type

R/W

Reset Value

00h

SMB_CTRL1 Register Map

STASTRE

NMINTE

GCMEN

ACK

RSVD

INTEN

STOP

START

SMB_CTRL1 Bit Descriptions

Bit

Name

Description

STASTRE

Stall After Start Enable.

0: When cleared, STASTR (SMB I/O Offset 01h[3]) can not be set. However, if

STASTR is set, clearing STASTRE will not clear STASTR.

1: Stall after start mechanism enabled, and SMB stalls the bus after the address byte.

6NMINTE

New Match Interrupt Enable.

0: No interrupt issued on a new match.

1: Interrupt issued on a new match only if INTEN (bit 2) is set.

5GCMEN

Global Call Match Enable.

0: SMB not responding to global call.

1: Global call match enabled.

4ACK

Receive Acknowledge. This bit is ignored in transmit mode. When the device acts as

a receiver (slave or master), this bit holds the transmitting instruction that is transmitted

during the next acknowledge cycle.

0: Cleared after acknowledge cycle.

1: Negative acknowledge issued on next received byte.

RSVD

Reserved. Reads return 0; writes have no effect.

2INTEN

Interrupt Enable.

0: SMB interrupt disabled.

1: SMB interrupt enabled. An interrupt is generated in response to one of the following

events:

-Detection of an address match (NMATCH, SMB I/O Offset 01h[2] = 1) and NMINTE

(bit 6) = 1.

-Receipt of bus error (BER, SMB I/O Offset 01h[5] = 1).

-Receipt of Negative Acknowledge after sending a byte (NEGACK, SMB I/O Offset

01h[4] = 1).

-Acknowledge of each transaction (same as the hardware set of the SDAST bit,

SMB I/O Offset 01h[6]) when DMA not enabled.

-In master mode if STASTRE = 1 (SMB I/O Offset 03h[7]), after a successful start

(STASTR = 1, SMB I/O Offset 01h[3]).

-Detection of a Stop condition while in slave mode (SLVSTP = 1, SMB I/O Offset

01h[7]).

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