Read VID and PID
from USB eFuses
eFuses programmed
?
Yes
No
Known VID
?
No
Yes
Take parameters from the
TI default table
Take parameters from the
customer table:
VID and PID from eFuses
Take parameters from the
default table:
VID and PID from eFuses
init-011
Public Version
www.ti.com
Device Initialization by ROM Code
Table 26-27. Customized Descriptor Parameters
Parameter
Size [Bytes]
Default Values
TI Default Values
Device ID code
2
0x0000
0x0000
Device class
1
0xFF
0xFF
Device subclass
1
0xFF
0xFF
Device protocol
1
0xFF
0xFF
Manufacturer
String
N/A
Texas Instruments
Product
String
Multimedia device or specific
Multimedia device or specific vendor string
vendor string
Serial number
String
See
(1)
See
(1)
(1)
The Standard device descriptor indicates that the device has no serial number.
describes an additional customer parameter selection method. It is based on the VID burned
in the USB eFuses.
Figure 26-12. Customer USB Descriptor Selection
26.4.5.3.3 USB Driver Functionality
•
Transactions supported
The following transactions are supported:
–
Control transactions: Used for standard device requests
–
Bulk transactions: Used for data transfer in the image downloading stage. The ASIC-ID is sent on
the Bulk IN endpoint and the image is transferred over the Bulk OUT endpoint from the host.
The USB first attaches to the host as an FS device. In the reset mechanism, the USB core requests
HS operation. If the HS negotiation in the reset phase is successful, further transactions are at HS;
otherwise, they are at FS. After reset, the USB driver checks for the speed of the device, whether it is
FS or HS. Depending on the speed configured by the host, the standard USB device requests are
responded to with the corresponding descriptors.
•
Standard device request restrictions
Because the USB driver is used only by the ROM code for peripheral booting, some standard device
requests are not supported by the driver.
lists the standard device requests supported by
3539
SWPU177N – December 2009 – Revised November 2010
Initialization
Copyright © 2009–2010, Texas Instruments Incorporated