LAN9730 datasheet(89/222 Pages) MICROCHIP

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DS00001946A-page 89

LAN9730/LAN9730i

4.7.2

EEPROM DEFAULTS

The signature value of 0xA5 is stored at address 0. A different signature value indicates to the EEPROM controller that

no EEPROM or an un-programmed EEPROM is attached to the device. In this case, the hardware default values are

used, as shown in Table 4-59. Refer to Section 4.3.1.6, "USB Descriptors" for further information about the default USB

values.

4.7.3

EEPROM AUTO-LOAD

Certain system level resets (USB reset, POR, nRESET, and SRST) cause the EEPROM contents to be loaded into the

device. After a reset, the EEPROM controller attempts to read the first byte of data from the EEPROM. If the value 0xA5

is read from the first address, then the EEPROM controller will assume that an external serial EEPROM is present.

The EEPROM controller will then load the entire contents of the EEPROM into an internal 512 byte SRAM. The contents

of the SRAM are accessed by the CTL (USB Control Block) as needed (i.e., to fill Get Descriptor commands). A detailed

explanation of the EEPROM byte ordering with respect to the MAC address is given in Section 6.4.3, "MAC Address

Low Register (ADDRL)".

If an 0xA5h is not read from the first address, the EEPROM controller will end initialization. The default values, as spec-

ified in Table 4-59, will then be assumed by the associated registers. It is then the responsibility of the host LAN driver

software to set the IEEE address by writing to the MAC’s ADDRH and ADDRL registers.

The device may not respond to the USB host until the EEPROM loading sequence has completed. Therefore, after

reset, the USB PHY is kept in the disconnect state until the EEPROM load has completed.

GPIO10 Detection Select

This bit selects the detection mode for GPIO10 when operating in PME mode. In PME mode, GPIO10 is

usable in both Internal and External PHY mode as a wakeup pin. This parameter defines whether the

wakeup should occur on an active high or active low signal.

0 = Active-low detection for GPIO10

1 = Active-high detection for GPIO10

Note:

If GPIO PME Enable is 0, this bit is ignored.

RESERVED

TABLE 4-59:

EEPROM DEFAULTS

Field

Default Value

MAC Address

FFFFFFFFFFFFh

Full-Speed Polling Interval (ms)

01h

Hi-Speed Polling Interval (ms)

04h

Configuration Flags

04h

Maximum Power (mA)

FAh

Vendor ID

0424h

Product ID

9730h

Note:

The Configuration Flags are affected by the RMT_WKP strap.

Note:

The USB reset only loads the MAC address.

TABLE 4-58:

GPIO PME FLAGS (CONTINUED)

Bits

Description

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