
Datasheet
Chapter 9 Hub Descriptors
The USB20H04 will not electrically attach to the USB until after it has loaded valid data for all
A hub returns different descriptors based on whether it is operating at
Table 9.1 - Device Descriptor
OFFSET | FULL | HIGH |
| FIELD NAME | DESCRIPTION |
SPEED | SPEED |
| |||
|
|
|
| ||
0 | 12h | 12h |
| bLength | Size of this descriptor in bytes |
1 | 01h | 01h |
| bDescriptorType | DEVICE Descriptor Type |
2,3 | 0200h | 0200h |
| bcdUSB | USB Specification Number |
4 | 09h | 09h |
| bDeviceClass | Class code assigned by |
5 | 00h | 00h |
| bDeviceSubClass | Class code assigned by |
6 | 00h | 01h* |
| bDeviceProtcol | Protocol code assigned by the |
7 | 40h | 40h |
| bMaxPacketSize0 | |
8,9 | user | user |
| idVendor | Vendor ID; OEM value |
10,11 | user | user |
| idProduct | Product ID; OEM value |
12,13 | user | user |
| bcdDevice | Device ID; OEM value |
14 | 00h | 00h |
| iManufacturer | This optional string is not supported. |
15 | 00h | 00h |
| iProduct | This optional string is not supported. |
16 | 00h | 00h |
| iSerialNumber | This optional string is not supported. |
17 | 01h | 01h |
| iNumConfigurations | Supports 1 configuration |
* 02h for |
|
|
| ||
|
|
| Table 9.2 - Device Qualifier Descriptor | ||
|
|
|
|
|
|
OFFSET | FULL | HIGH |
| FIELD NAME | DESCRIPTION |
SPEED | SPEED |
| |||
|
|
|
| ||
0 | 0Ah | 0Ah |
| bLength | Size of this descriptor in bytes |
1 | 06h | 06h |
| bDescriptorType | DEVICE Qualifier Type |
2 | 00h | 00h |
| bcdUSB | USB Specification Version Number (LSB) |
3 | 02h | 02h |
| bcdUSB | USB Specification Version Number (MSB) |
4 | 09h | 09h |
| bDeviceClass | Class code assigned by |
5 | 00h | 00h |
| bDeviceSubClass | Class code assigned by |
6 | 00h | 01h* |
| bDeviceProtcol | Protocol code. |
|
| ||||
|
|
|
|
|
|
7 | 40h | 40h |
| bMaxPacketSize0 | |
8 | 01h | 01h |
| bNumConfigurations | Supports 1 other speed configuration |
9 | 00h | 00h |
| bReserved | Reserved |
|
|
|
|
|
|
* 02h for
Revision 1.63 | Page 28 | SMSC USB20H04 |
DATASHEET