Hi-Speed USB 2.0 to 10/100 Ethernet Controller

Datasheet

Chapter 3 EEPROM Controller (EPC)

LAN9500/LAN9500i may use an external EEPROM to store the default values for the USB descriptors and the MAC address. The EEPROM controller supports most “93C46” type EEPROMs. The EEP_SIZE strap selects the size of the EEPROM attached to LAN9500/LAN9500i. When this strap is set to “0”, a 128 byte EEPROM is attached and a total of seven address bits are used. When this strap is set to “1” a 256/512 byte EEPROM is attached and a total of nine address bits are used.

Note: A 3-wire style 1K/2K/4K EEPROM that is organized for 128 x 8-bit or 256/512 x 8-bit operation must be used.

The MAC address is used as the default Ethernet MAC address and is loaded into the MAC’s ADDRH and ADDRL registers. If a properly configured EEPROM is not detected, it is the responsibility of the Host LAN Driver to set the IEEE addresses.

After a system-level reset occurs, LAN9500/LAN9500i will load the default values from a properly configured EEPROM. LAN9500/LAN9500i will not accept USB transactions from the Host until this process is completed.

The LAN9500/LAN9500i EEPROM controller also allows the Host system to read, write and erase the contents of the Serial EEPROM.

3.1EEPROM Format

Table 3.1 illustrates the format in which data is stored inside of the EEPROM.

Note the EEPROM offsets are given in units of 16-bit word offsets. A length field with a value of zero indicates that the field does not exist in the EEPROM. The LAN9500/LAN9500i will use the field’s HW default value in this case.

Note: For the device descriptor, the only valid values for the length are 0 and 18.

Note: For the configuration and interface descriptor, the only valid values for the length are 0 and 18.

Note: The EEPROM programmer must ensure that if a string descriptor does not exist in the EEPROM, the referencing descriptor must contain 00h for the respective string index field.

Note: If all string descriptor lengths are zero, then a Language ID will not be supported.

 

Table 3.1 EEPROM Format

 

 

EEPROM ADDRESS

EEPROM CONTENTS

 

 

00h

0xA5

 

 

01h

MAC Address [7:0]

 

 

02h

MAC Address [15:8]

 

 

03h

MAC Address [23:16]

 

 

04h

MAC Address [31:24]

 

 

05h

MAC Address [39:32]

 

 

06h

MAC Address [47:40]

 

 

07h

Full-Speed Polling Interval for Interrupt Endpoint

 

 

08h

Hi-Speed Polling Interval for Interrupt Endpoint

 

 

Revision 1.7 (10-02-08)

20

SMSC LAN9500/LAN9500i

 

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