VSC8658 datasheet(68/95 Pages) MICROSEMI

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Configuration

VMDS-10242 VSC8658 Datasheet Revision 4.1

the EEPROM, refer to the EEPROM’s specific datasheet to ensure that write protection on the EEPROM

is not set.

The following illustration shows the interaction of the VSC8658 device and the EEPROM.

Figure 18 •

EEPROM Read and Write Register Flow

To read a value from a specific address of the EEPROM:

Read the VSC8658 device register bit 21E.11, and ensure that it is set.

Write the EEPROM address to be read to register bits 21E.10:0.

Set both register bits 21E.12 and 21E.13 to 1.

When register bit 21E.11 changes to 1, read the 8-bit data value found at register bits 22E.15:8. This

is the contents of the address just read by the PHY.

To write a value to a specific address of the EEPROM:

Read the VSC8658 device register bit 21E.11 and ensure that it is set.

Write the address to be written to register bits 21E.10:0.

Set register bit 21E.12 to 0.

Set register bits 22E.7:0 with the 8-bit value to be written to the EEPROM.

Set register bit 21E.13 to 1.

To avoid collisions during read and write transactions, always wait until register bit 21E.11 changes to 1

before performing another EEPROM read or write operation.

Wait for Ready

21E.11 = 0

21E.11 = 1

Read or Write

21E.10:0 = Write Address

21E.12 = 0

22E.7:0 = Data to Write

Write EEPROM

Data

21E.10:0 = Address to Read

21E.12 = 1

21E.13 = 1

Wait for Ready

21E.11 = 0

21E.11 = 1

Read EEPROM

Data

Read Data = 22E.15:8

Start

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