AN2131-DK001 Cypress Semiconductor Corp, AN2131-DK001 Datasheet - Page 134

• Manufacturer Part Number: AN2131-DK001
• Description: KIT EZ-USB DEVELOPMENT BOARD
• Manufacturer: Cypress Semiconductor Corp

Specifications of AN2131-DK001

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 428-1333

(over EP0-IN) such information as what device driver to load, how many endpoints it has,
its different configurations, alternate settings it may use, and informative text strings about
the device.
The EZ-USB core provides a special Setup Data Pointer to simplify 8051 service for
Get_Descriptor requests. The 8051 loads this 16-bit pointer with the beginning address of
the requested descriptor, clears the HSNAK bit (by writing “1” to it), and the EZ-USB
core does the rest.
Figure 7-5 illustrates use of the Setup Data Pointer. This pointer is implemented as two
registers, SUDPTRH and SUDPTRL. Most Get_Descriptor requests involve transferring
more data than will fit into one packet. In the Figure 7-5 example, the descriptor data con-
sists of 91 bytes.
EZ-USB TRM v1.9
Token Packet
Token Packet
Token Packet
S
E
T
U
P
N
I
O
U
T
A
D
D
R
A
D
D
R
A
D
D
R
STATUS Stage
E
N
D
P
Figure 7-5. Using the Setup Data Pointer (SUDPTR) for Get_Descriptor Requests
E
N
D
P
E
N
D
P
C
R
C
5
C
R
C
5
C
R
C
5
SETUP Stage
Data Pkt
D
A
T
A
1
D
A
T
A
1
D
A
T
A
0
Data Packet
Data Packet
C
R
C
1
6
8 bytes
Setup
Data
Payload
Data
H/S Pkt
A
C
K
C
R
C
1
6
C
R
C
1
6
H/S Pkt
Chapter 7. EZ-USB CPU
H/S Pkt
A
C
K
SUDAV Interrupt
DATA Stage
A
C
K
Interrupt
EP0IN
Token Packet
SUDPTRH/L
N
I
64 bytes
27 bytes
8 RAM
A
D
D
R
bytes
E
N
D
P
C
R
C
5
SETUPDAT
D
A
T
A
0
Data Packet
Payload
Data
Interrupt
EP0IN
C
R
C
1
6
H/S Pkt
Page 7-13
A
C
K