TNETX3150 datasheet(48/78 Pages) TI

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TNETX15AE

ADDRESS-LOOKUP DEVICE

SPWS041A – AUGUST 1997 – REVISED OCTOBER 1997

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

PRINCIPLES OF OPERATION

host (access) register space (continued)

The next two bytes, DIO data and DIO data auto-increment, are used to read and write data to the byte-wide

internal register selected in the DIOADR. Both DIO data and DIO data auto-increment can be used effectively

to read and write the data, but the DIO data auto-increment register provides additional functionality over DIO

data. Access to the DIO data auto-increment register provides a post-increment (by one) to the DIO address

As an example, to access a single-byte-wide register such as the SIO register (DIO address = 0x0A) the

operations needed are:

D Write a 0x00 to DIO address high

D Write a 0x0A to DIO address low to select DIO address 0x0A

D Read the SIO register by reading DIO data, or write to the SIO register by writing to DIO data.

Multiple-byte registers are accessed by reading/writing to their individual bytes. The control register (DIO

address 0x08–0x09) is accessed in the following manner:

D Write a 0x00 to DIO address high

D Write a 0x08 to DIO address low to select DIO address 0x08

D Read the least-significant byte of the control register by reading DIO data, or write to the least-significant

byte of the control register by writing to DIO data.

D Write a 0x00 to DIO address high

D Write a 0x09 to DIO address low to select DIO address 0x09

D Read the most-significant byte of the control register by reading DIO data, or write to the most-significant

byte of the control register by writing to DIO data.

Improvement on the preceding steps is obtained by writing a 0x00 to DIO address high and changing only DIO

address low. More steps can be eliminated by using the DIO data auto-increment register to read or write to

contiguous register bytes. The following shows how to use the auto-incrementing function to access the control

D Write a 0x00 to DIO address high

D Write a 0x08 to DIO address low to select DIO address 0x08

D Read the least-significant byte of the control register by reading DIO data auto-increment or write to the

least-significant byte of the control register by writing to DIO data auto-increment. The address in DIO

address auto-increments to 0x0009.

D Read the most-significant byte of the control register by reading DIO data auto-increment, or write to the

most-significant byte of the control register by writing to DIO data auto-increment.

The auto-incrementing function is useful when reading or writing to a large number of adjacent registers, such

as the 48-bit address registers or when reading the statistics block.

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