LAN9730 Datasheet, PDF (40/222 Pages) SMSC Corporation – High-Speed Inter-Chip (HSIC) USB 2.0

LAN9730/LAN9730i
Note:
EEPROM values are from the Device Descriptor (including any EEPROM override) at the opposite HS/FS
operating speed. I.e., if the current operating speed is HS, then Device Qualifier data is based on the FS
Device Descriptor, and vice-versa.
Note 4-13
Value is loaded from EEPROM, but must be equal to the default value in order to comply with the USB
2.0 Specification and provide for normal device operation. Specification of any other value will result
in unwanted behavior and untoward operation.
4.3.1.6.9 String Descriptors
String Index = 0 (LANGID)
TABLE 4-12: LANGID STRING DESCRIPTOR
Offset
Field
00h bLength
Size
(Bytes)
1
Default
Value
04h
01h bDescriptorType
02h LANGID
1
03h
2
None
Loaded
from
EEPROM
No
No
Yes
Description
Size of LANGID Descriptor in bytes
(4 bytes)
String Descriptor (0x03)
Must be set to 0x0409 (US English).
Note: If there is no valid/enabled EEPROM, or if all string lengths in the EEPROM are 0, then there are no strings,
so any host attempt to read the LANGID string will return stall in the Data Stage of the Control Transfer.
If there is a valid/enabled EEPROM, and if at least one of the string lengths in the EEPROM is not 0, then
the value contained at EEPROM addresses 0x0A-0x0B will be returned. These must be 0x0409 to allow
for proper device operation.
Note: The device ignores the LANGID field in Control Read’s of Strings, and will not return the String (if it exists),
regardless of whether the requested LANGID is 0x0409 or not.
String Indices 1-5
TABLE 4-13: STRING DESCRIPTOR (INDICES 1-5)
Offset
Field
00h bLength
01h bDescriptorType
02h Unicode String
Size
(Bytes)
1
1
2*N
Default
Value
none
none
none
Loaded
from
EEPROM
Yes
Yes
Yes
Description
Size of the String Descriptor in bytes
(4 bytes)
String Descriptor (0x03)
2 bytes per unicode character, no trail-
ing NULL.
Note:
Note:
If there is no valid/enabled EEPROM, or if the corresponding String Length and offset in the EEPROM for
a given string index are zero, then that string does not exist, so any host attempt to read that string will
return stall in the Data Stage of the Control Transfer.
The device returns whatever bytes are in the designated EEPROM area for each of these strings. It is the
responsibility of the EEPROM programmer to correctly set the bLength and bDescriptorType fields in the
descriptor consistent with the byte length specified in the corresponding EEPROM locations.
DS00001946A-page 40
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