Datasheet
Table 9.7 - Interface Descriptor (present if
OFFSET | HIGH | FIELD NAME | DESCRIPTION | |
| SPEED |
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0 | 09h | bLength | Size of this descriptor in bytes | |
1 | 04h | bDescriptorType | INTERFACE Descriptor Type | |
2 | 00h | bInterfaceNumber | Number of this interface | |
3 | 01h | bAlternateSetting | Value used to select this alternate setting for | |
the interface | ||||
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4 | 01h | bNumEndpoints | Number of endpoints used by this interface (not | |
including endpoint 0) | ||||
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5 | 09h | bInterfaceClass | Class code assigned by USB for Hubs | |
6 | 00h | bInterfaceSubClass | Subclass code assigned by USB | |
7 | 02h | bInterfaceProtcol | Protocol code assigned by USB | |
8 | 00h | bInterface | Index of string descriptor describing this | |
configuration (string not supported) | ||||
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Table 9.8 -
OFFSET | FULL | HIGH SPEED | FIELD NAME | DESCRIPTION | |
SPEED | |||||
0 | 03h | 03h | bLength | Size of this descriptor in bytes | |
1 | 09h | 09h | bDescriptorType | OTG Descriptor Type | |
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| Attribute Fields: | |
2 | 01h | 01h | wMaxPacketSize | D[7:2] = Reserved | |
D1: HNP Support (not supported) | |||||
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| D0: SRP Support. | |
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Table 9.9 -
| OFFSET | FIELD NAME | VALUE |
| DESCRIPTION |
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| 0 | Length | 09h |
| Size of this Descriptor. |
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| 1 | Descriptor Type | 29h |
| Hub Descriptor Type. |
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| 2 | NbrPorts | user |
| Number of downstream facing ports this Hub |
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| supports. Derived from OEM value defined in |
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| EEPROM or SMBus load. See Section 11.23.2.1 in |
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| the USB Specification. |
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| Note: If Dynamic Power is enabled, and the |
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| SELF_PWR pin is low (indicating Bus Power |
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| Operation), then ports 3 & 4 are not available and |
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| either a value of 1 is reported if the OEM value is 1 |
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| or a value of 2 is reported if the OEM value is 2, 3 |
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| or 4. |
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| 3,4 | HubCharacteristics | user |
| Defines several characteristics that are derived |
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| from OEM values. Also defines TT Think Time |
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| (fixed at a value of 00b for 8FS bit times max). |
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| 5 | PwrOn2PwrGood | user |
| Time (in 2 ms intervals) from the time the |
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| sequence begins on a port until power is good on |
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| that port. Derived from OEM value. |
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SMSC USB20H04 |
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| Page 31 | Revision 1.63 | |||
DATASHEET