KSZ9567RTXI-TR datasheet(190/232 Pages) MICROCHIP

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KSZ9567R

DS00002329D-page 190

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5.3.1.2

Address Lookup Table Search Operation

The second method to access the Address Lookup Table is through the search operation. The entire table is searched

sequentially, revealing each valid entry. Invalid address entries are skipped, providing an efficient way to search the

entire table. Setting the START_FINISH bit in the ALU Table Access Control Register begins the search from the top of

the table. This bit is cleared when the search is complete. During the table search, the VALID bit in the ALU Table Access

Control Register is cleared when the search starts. The VALID bit indicates when a found valid entry is available in the

ALU Table Entry registers (0x0420 - 0x042F). After reading the last ALU Table Entry register (ALU Table Entry 4 Reg-

ister), the search process automatically continues to seek the next valid entry in the address table. The START_FINISH

bit remains set until all the valid entries in the table have been returned. The search can be stopped any time by setting

the ALU Table Access Control Register START_FINISH bit to 0.

Write to the ALU Table Access Control Register.

a) Set the ACTION field to 11 to indicate a search operation.

b) Set the START_FINISH bit to initiate the operation.

Poll the VALID bit until it is set.

a) If register access is by in-band management (IBA) rather than SPI or I2C, poll VALID_ENTRY_OR_-

SEARCH_END instead. This bit goes high to indicate either a new valid entry is returned or the search is

complete.

Read the entry from the ALU Table Entry 1 Register, ALU Table Entry 2 Register, ALU Table Entry 3 Register,

and ALU Table Entry 4 Register, in that order.

a) If the search has ended and there are no more valid entries to read, these registers will return all zeros. In

this case, go to step 5.

If START_FINISH = 0, go to step 5; else go to step 2.

Read VALID_COUNT to verify the number of valid entries.

5.3.1.3

Address Lookup Table Write Operation

Perform a read operation to get the contents of the current entry. The values are kept in the ALU Table Entry 1

Modify the correct entry as necessary. Set the STATIC bit so that the entry is not aged out.

Write to the ALU Table Access Control Register.

a) Set the ACTION field to 01 to indicate a write operation.

b) Select the addressing method via the DIRECT bit.

c) Set the START_FINISH bit to initiate the operation.

KSZ9567RTXI-TR Datasheet(PDF) 190 Page - Microchip Technology