
PC Card Controller Programming Model
103
September 2005
SCPS110
4.46 Serial Bus Data Register
The serial bus data register is for programmable serial bus byte reads and writes. This register represents the
data when generating cycles on the serial bus interface. To write a byte, this register must be programmed
with the data, the serial bus index register must be programmed with the byte address, the serial bus slave
address must be programmed with the 7-bit slave address, and the read/write indicator bit must be reset.
On byte reads, the byte address is programmed into the serial bus index register, the serial bus slave address
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 4.49) must be polled until clear. Then
the contents of this register are valid read data from the serial bus interface. See Table 422 for a complete
description of the register contents.
PCI register offset:
B0h (function 0)
Register type:
Read/Write
Default value:
00h
BIT NUMBER
7
6
5
4
3
2
1
0
RESET STATE
0
Table 422. Serial Bus Data Register Description
BIT
SIGNAL
TYPE
FUNCTION
70
SBDATA
RW
Serial bus data. This bit field represents the data byte in a read or write transaction on the serial interface.
On reads, the REQBUSY bit must be polled to verify that the contents of this register are valid.
These bits are cleared only by the assertion of GRST.
4.47 Serial Bus Index Register
The serial bus index register is for programmable serial bus byte reads and writes. This register represents
the byte address when generating cycles on the serial bus interface. To write a byte, the serial bus data register
must be programmed with the data, this register must be programmed with the byte address, and the serial
bus slave address must be programmed with both the 7-bit slave address and the read/write indicator.
On byte reads, the word address is programmed into this register, the serial bus slave address 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 4.49) 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 423 for a complete
description of the register contents.
PCI register offset:
B1h (function 0)
Register type:
Read/Write
Default value:
00h
BIT NUMBER
7
6
5
4
3
2
1
0
RESET STATE
0
Table 423. Serial Bus Index Register Description
BIT
SIGNAL
TYPE
FUNCTION
70
SBINDEX
RW
Serial bus index. This bit field represents the byte address in a read or write transaction on the serial interface.
These bits are cleared only by the assertion of GRST.