7.3.1 Get Status
The USB Specification version 1.0 defines three USB status requests. A fourth request, to
an interface, is indicated in the spec as “reserved.” The four status requests are:
•
•
•
•
Remote Wakeup (Device request)
Self-Powered (Device request)
Stall (Endpoint request)
Interface request (“reserved”)
The EZ-USB core activates the SUDAV interrupt request to tell the 8051 to decode the
SETUP packet and supply the appropriate status information.
SETUP Stage
S
E
T
U
P
D
A
T
A
0
C
R
C
1
A
D
D
R
E
N
D
P
C
R
C
5
8 bytes
Setup
Data
A
C
K
SETUPDAT
8 RAM
bytes
6
Token Packet
Data Packet
H/S Pkt
SUTOK
Interrupt
SUDAV
Interrupt
DATA Stage
D
A
T
A
1
C
R
C
1
A
D
D
R
E
N
D
P
C
R
C
5
A
C
K
I
N
2
Bytes
6
H/S Pkt
Data Packet
Token Packet
IN0BUF
IN0BC
64-byte
Buffer
STATUS Stage
D
A
T
A
1
C
R
C
1
A
D
D
R
E
N
D
P
C
R
C
5
O
U
T
A
C
K
2
6
Token Packet
Data Pkt
H/S Pkt
Figure 7-4. Data Flow for a Get_Status Request
EZ-USB TRM v1.9
Chapter 7. EZ-USB CPU
Page 7-7
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