Fusion 878A
5.0 Control Register Definitions-Function 0
PCI Video Decoder
5.3 Local Registers (Memory Mapped)
100600B
Conexant
5-35
0x110—I2C Data/Control Register
Bits
Type
Default
Name
Description
[31:24]
RW
—
I2CDB0
First byte sent in an I
2
C transaction. Typically this will be the base or chip
7-bit address and the R/W bit.
[23:16]
RW
—
I2CDB1
Second byte sent in an I
2
C write transaction, usually a sub-address.
[15:8]
RW
—
I2CDB2
Third byte sent in an I
2
C write transaction, usually the data byte. After a read
transaction, this byte register will contain the data read from the slave.
[7]
RW
0
I2CMODE
I
2
C mode.
0 = Software mode
1 = Hardware mode
[6]
RW
0
I2CRATE
I
2
C timing frequency.
0 = 99.2 kHz mode
1 = 396.8 kHz mode
[5]
RW
0
I2CNOSTOP
I
2
C stop mode.
0 = Transmits stop at end of transaction
1 = Does not transmit stop at end of transaction. Holds SCL low.
[4]
RW
0
I2CNOS1B
I
2
C start mode.
0 = Transmits START or repeated START transactions. The R/W status
from bit 24 is saved for any future 1 byte transactions.
1 = Enables 1 byte read or write without START
[3]
RW
0
I2CSYNC
I
2
C synchronization.
0 = Disallows the slave to insert wait states
1 = Allows the slave to insert bit-level clock wait states
[2]
RW
0
I2CW3BRA
Number of bytes sent and master/slave acknowledge. This bit has no
meaning when I2CNOS1B (bit 4) is high during a write transaction.
0 = Writes transaction of 2 bytes I2CDB(0-1). During a 1-byte read trans-
action (I2CNOS1B is high), master sends a NACK to end the reads
from the slave.
1 = Writes transaction of 3 bytes I2CDB(0-2). During a 1-byte read trans-
action (I2CNOS1B is high), master sends an ACK after reading the
data byte.
[1]
RW
1
I2CSCL
A value of 1 releases the SCL output, and a 0 forces the SCL output low. This
bit must be set to a 1 during hardware mode. This override is for direct
software control of the bus. Reading this bit provides access to the buffered
SCL input pin.
[0]
RW
1
I2CSDA
A value of 1 releases the SDA output, and a 0 forces the SDA output low. This
bit must be set to a 1 during hardware mode. This override is for direct
software control of the bus. Reading this bit provides access to the buffered
SDA input pin.