USB3803 datasheet(46/99 Pages) MICROCHIP

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USB3803

DS00001691B-page 46

 2014-2015 Microchip Technology Inc.

7.0

USB DESCRIPTORS

A customer can indirectly affect which descriptors are reported via one of two methods. The two methods are: Internal

Default ROM Configuration, or direct load through the serial port interface.

The Microchip Hub will not electrically attach to the USB until after it has loaded valid data for all user- defined descriptor

fields (either through Internal Default ROM, or serial port).

7.1

USB Bus Reset

In response to the upstream port signaling a reset to the Hub, the Hub does the following:

• The Hub does not propagate the upstream USB reset to downstream devices.

• Sets default address to 0.

• Sets configuration to: Unconfigured.

• Negates PRTPWR[3:1] register for all downstream ports.

• Clears all TT buffers.

• Moves device from suspended to active (if suspended).

• Complies with Section 11.10 of the USB 2.0 Specification for behavior after completion of the reset sequence.

The Host then configures the Hub and the Hub's downstream port devices in accordance with the USB Specification.

7.2

Hub Attached as a Full-Speed Device, (High-Speed Disabled)

When High-Speed capability is disabled via customer configuration options, the hub will only be able to attach as a Full-

Speed device, and the following descriptor information applies.

7.2.1

STANDARD DEVICE DESCRIPTOR

The following table provides the descriptor values for Full-Speed operation.

TABLE 7-1:

DEVICE DESCRIPTOR (FULL-SPEED)

Offset

Field

Size

Value

Description

Length

12h

Size of this Descriptor.

DescriptorType

01h

Device Descriptor Type.

USB

0200h

USB Specification Release Number.

DeviceClass

09h

Class code assigned by USB-IF for Hubs.

DeviceSubClass

00h

Class code assigned by USB-IF for Hubs.

DeviceProtocol

00h

Protocol code.

MaxPacketSize0

40h

64-byte packet size.

Vendor

user/

default

Vendor ID; customer value defined in ROM or serial port

load.

Product

user/

default

Product ID; customer value defined in ROM or serial

port load.

Device

user/

default

Device ID; customer value defined in ROM or serial port

load.

Manufacturer

xxh

If STRING_EN =0 Optional string is not supported, and

xx = 00.

If STRING_EN = 1, String support is enabled, and

xx = 01

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