Cypress Semiconductor FX2LP Informacje Techniczne Strona 69

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Chapter 2. Endpoint Zero Page 2-15
Data Pointer. However, this would waste bandwidth because it requires byte transfers into the
EP0BUF Buffer; using the Setup Data Pointer doesn’t.
2.3.4.2 Get Descriptor-Device Qualifier
The Device Qualifier descriptor is used only by devices capable of high-speed (480 Mbps) opera-
tion; it describes information about the device that would change if the device were operating at
the other speed (i.e., if the device is currently operating at high speed, the device qualifier returns
information about how it would operate at full speed and vice-versa).
Device Qualifier descriptors are handled just like Device descriptors; the firmware loads the appro-
priate descriptor address into SUDPTRH:L, then the FX2 does the rest.
2.3.4.3 Get Descriptor-Configuration
Table 2-11. Get Descriptor-Device Qualifier
Byte Field Value Meaning Firmware Response
0 bmRequestType 0x80 IN, Device
Set SUDPTR H:L to start of
1 bRequest
0x06
“Get_Descriptor”
the appropriate Device Qualifier
2 wValueL 0x00
Descriptor table in RAM.
3wValueH
0x06
Descriptor Type: Device Quali-
fier
4 wIndexL 0x00
5 wIndexH 0x00
6 wLengthL LenL
7 wLengthH
LenH
Table 2-12. Get Descriptor-Configuration
Byte Field Value Meaning Firmware Response
0 bmRequestType
0x80
IN, Device
Set SUDPTR H:L to start of
1 bRequest
0x06
“Get_Descriptor”
Configuration Descriptor table in
2wValueL CFG Configuration Number
RAM
3wValueH 0x02 Descriptor Type: Configuration
4 wIndexL 0x00
5 wIndexH 0x00
6 wLengthL LenL
7 wLengthH LenH
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