AN2131-DK001 Cypress Semiconductor Corp, AN2131-DK001 Datasheet - Page 139

• 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

Page 7-18
Configurations, Interfaces, and Alternate Settings
Configurations, Interfaces, and Alternate
Settings
A USB device has one or more configu-
ration. Only one configuration is active
at any time.
A configuration has one or more inter-
face, all of which are concurrently active.
Multiple interfaces allow different host-
side device drivers to be associated with
different portions of a USB device.
Each interface has one or more alternate
setting. Each alternate setting has a col-
lection of one or more endpoints.
This structure is a software model; the EZ-USB core takes no action when these settings
change. However, the 8051 must re-initialize endpoints when the host changes config-
urations or interfaces alternate settings.
As far as 8051 firmware is concerned, a configuration is simply a byte variable that indi-
cates the current setting.
The host issues a Set_Coniguration request to select a configuration, and a
Get_Configuration request to determine the current configuration.
Chapter 7. EZ-USB CPU
Interface 0
CDROM
control
Alt Setting
0
Interface 1
audio
Alt Setting
High Power
Config 1
1
Interface 2
video
Device
ep
Alt Setting
ep
3
Low Power
Config 2
Interface 3
storage
ep
data
EZ-USB TRM v1.9
One at a time
One at a time
Concurrent