7.3.3 Clear Feature
Clear Feature is used to disable remote wakeup or to clear a stalled endpoint.
Table 7-8. Clear Feature-Device (Clear Remote Wakeup Bit)
Byte
Field
bmRequestType
bRequest
Value
Meaning
8051 Response
0
1
2
0x00 OUT, Device
Clear the remote wakeup bit
0x01 “Clear Feature”
wValueL
0x01 Feature Selector:
Remote Wakeup
3
4
5
6
7
wValueH
wIndexL
wIndexH
wLengthL
wLengthH
0x00
0x00
0x00
0x00
0x00
Table 7-9. Clear Feature-Endpoint (Clear Stall)
Byte
Field
bmRequestType
bRequest
Value
Meaning
8051 Response
Clear the STALL bit for the
indicated endpoint:
0
1
2
0x02 OUT, Endpoint
0x01 “Clear Feature”
wValueL
0x00 Feature Selector:
STALL
3
4
5
6
7
wValueH
wIndexL
wIndexH
wLengthL
wLengthH
0x00
EP
EP(n):
0x00
0x00
0x00
0x00-0x07: OUT0-OUT7
0x80-0x87: IN0-IN7
If the USB device supports remote wakeup (as reported in its descriptor table when the
device is enumerated), the Clear_Feature/Remote Wakeup request disables the wakeup
capability.
The Clear_Feature/Stall removes the stall condition from an endpoint. The 8051 should
respond by clearing the stall bit in the indicated endpoint’s CS register.
7.3.4 Get Descriptor
During enumeration, the host queries a USB device to learn its capabilities and require-
ments using Get_Descriptor requests. Using tables of descriptors, the device sends back
Page 7-12
Chapter 7. EZ-USB CPU
EZ-USB TRM v1.9
CYPRESS [ CYPRESS ]
