PCI6421 datasheet(111/204 Pages) TI

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4−35

4.49 Serial Bus Slave Address Register

The serial bus slave address register is for programmable serial bus byte read and write transactions. To write a byte,

the serial bus data register must be programmed with the data, the serial bus index register must be programmed

with the byte address, and this register must be programmed with both the 7-bit slave address and the read/write

indicator bit.

On byte reads, the byte address is programmed into the serial bus index register, this register must be programmed

with both the 7-bit slave address and the read/write indicator bit, and bit 5 (REQBUSY) in the serial bus control and

status register (see Section 4.50) must be polled until clear. Then the contents of the serial bus data register are valid

read data from the serial bus interface. See Table 4−24 for a complete description of the register contents.

Bit

Name

Serial bus slave address

Type

Default

Serial bus slave address

Offset:

B2h (function 0)

Type:

Read/Write

Default:

00h

Table 4−24. Serial Bus Slave Address Register Description

BIT

SIGNAL

TYPE

FUNCTION

7−1 ‡

SLAVADDR

Serial bus slave address. This bit field represents the slave address of a read or write transaction on the

serial interface.

0 ‡

RWCMD

Read/write command. Bit 0 indicates the read/write command bit presented to the serial bus on byte read

and write accesses.

0 = A byte write access is requested to the serial bus interface.

1 = A byte read access is requested to the serial bus interface.

‡ One or more bits in this register are cleared only by the assertion of GRST.

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