CS5530A datasheet(235/259 Pages) NSC

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Table 4-39. Signature/Length Block for 0x43

Byte

Offset

Value

Signature: Always 0x00000070

Length: The length of the entire buffer including the signature block in bytes.

Reserved: Set to 0

Table 4-40. I/O Block for 0x43

Byte

Offset

Description

BYTE: Operation Type.

1 = Read

2= Write

3 = Read/And/Or/Write

4 = Define index and data ports

In addition, values may be OR’ed in to the upper two bits of this byte to indicate that special functions are desired.

0x80 = Do not perform this operation (convert to NO-OP).

0x40 = This is an index operation.

BYTE: Reserved set to 0

BYTE: I/O Length - Determines whether a BYTE, WORD or DWORD operation is performed.

1 = BYTE operation

2 = WORD operation

3 = DWORD operation

If BYTE 0 is a 4, then this field is used to indicate the size of the index write.

BYTE: Reserved set to 0

DWORD: I/O Address - This is the address in the I/O space to be used. It is always a WORD value. If this is a define

index/data port operation, this DWORD contains the I/O address of the index port.

If this is an index operation, other than define, this DWORD contains the value to be written to the index port.

DWORD: I/O Data - The meaning depends on the operation type.

Read = This is where the data read from the I/O port will be placed.

Write = This is the data to write to the I/O port.

Read/AND/OR/Write = This is the data that will be ANDed with the data read from the I/O port.

Define index/data port - This DWORD contains the I/O address of the data port.

DWORD: OR Data - This field is only used in a Read/AND/OR/Write operation. It contains the data that will be OR’ed after

the data read was AND’ed with the previous field. After the OR is done, the data will be re-written to the I/O port.

Note: In all cases if the data called for is shorter than the field, the data will be stored or retrieved from the least significant portion of the

DWORD.

CS5530A Datasheet(PDF) 235 Page - National Semiconductor (TI)