Cypress Semiconductor FX2LP Información técnica Pagina 70

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EZ-USB FX2 Technical Reference Manual
Page 2-16 EZ-USB FX2 Technical Reference Manual v2.1
2.3.4.4 Get Descriptor-String
Configuration and String descriptors are handled similarly to Device descriptors. The firmware
reads byte 2 of the SETUP data to determine which configuration or string is being requested,
then loads the corresponding descriptor address into SUDPTRH:L. The FX2 does the rest.
2.3.4.5 Get Descriptor-Other Speed Configuration
The Other Speed Configuration descriptor is used only by devices capable of high-speed (480
Mbps) operation; it describes the configuration(s) of the device if it were operating at the other
speed (i.e., if the device is currently operating at high speed, the Other Speed Configuration
returns information about full-speed configuration and vice-versa).
Other Speed Configuration descriptors are handled just like Configuration descriptors; the firm-
ware loads the appropriate descriptor address into SUDPTRH:L, then the FX2 does the rest.
Table 2-13. Get Descriptor-String
Byte Field Value Meaning Firmware Response
0 bmRequestType 0x80 IN, Device
Set SUDPTR H:L to start of
1 bRequest
0x06
“Get_Descriptor”
String Descriptor table in
2wValueL
STR
String Number
RAM.
3wValueH
0x03
Descriptor Type: String
4 wIndexL 0x00 (Language ID L)
5 wIndexH 0x00 (Language ID H)
6 wLengthL
LenL
7 wLengthH
LenH
Table 2-14. Get Descriptor-Other Speed Configuration
Byte Field Value Meaning Firmware Response
0 bmRequestType 0x80 IN, Device
Set SUDPTR H:L to start of
1 bRequest
0x06
“Get_Descriptor”
Other Speed Configuration
2wValueL
CFG
Other Speed
Configuration Number
Descriptor table in RAM.
3wValueH
0x07
Descriptor Type: Other
Speed Configuration
4 wIndexL 0x00 (Language ID L)
5 wIndexH 0x00 (Language ID H)
6 wLengthL LenL
7 wLengthH LenH
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