USB5926CSLASHKD datasheet(45/66 Pages) MICROCHIP

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2016-2021 Microchip Technology Inc.

DS00002234E-page 45

USB5926

8.8.2

BILLBOARD ENDPOINT FUNCTIONALITY

When the applicable

GPIOx pin is 0, which indicates that Billboard device must be displayed, the following sequence

of events will occur:

1. USB5926 will force the Hub Feature Controller internal device to disconnect from the USB Hub port (emulating

a physical detach)

2. USB5926 will force the Hub Feature Controller to re-connect with descriptors that will show the Hub Feature Con-

troller endpoint is a Billboard device, compliant to version 1.1 of the Billboard device class specification.

3. USB5926 will start a timer (Timer A) when the Host sets the Hub Feature Controller USB address. This timer will

be used to ensure that the Billboard endpoint will not remain permanently attached if it is never accessed. The

default Timer A timeout is 20 seconds.

4. This implementation will only support Billboard when a failure occurs, therefore the Device Container uses a

static list of device capabilities and will only expose the Billboard Device on failure to enter into Modal Operation

and will set the

bmConfigured descriptor field to “Unspecified Error” (00b) by default.

5. The Hub Feature Controller will Provide the iAlternateModeString when the host requests it, and will start a timer

(Timer B). The default Timer B timeout is 20 seconds.

6. When either timer expires, the USB5926 will force the Hub Feature Controller internal device to disconnect from

the USB Hub port (emulating a physical detach).

7. USB5926 will force the Hub Feature Controller to re-connect with the standard Hub Feature Controller Function-

ality.

TABLE 8-11: TIMER A: BILLBOARD DETACH TIMER LSB

DETACH_TIMER_A_LSB

(413Ch)

Billboard Detach Timer A LSB

BIT

Name

R/W

Description

7:0

TIMEOUT

R/W

Timer A is started as soon as the Hub Feature Controller’s Billboard

Class Device address is set by the host. Once the timer expires, the

Billboard Class Device will automatically detach from the host and re-

attach as the default WinUSB device.

Increments of 10ms can be set.

The default value of 413Ch = D0h, 413Dh = 07h is equivalent to a 20s

timeout. (07D0h = 2000d)

TABLE 8-12: TIMER A: BILLBOARD DETACH TIMER MSB

DETACH_TIMER_A_MSB

(413Dh)

Billboard Detach Timer A MSB

BIT

Name

R/W

Description

7:0

TIMEOUT

R/W

Timer A is started as soon as the Hub Feature Controller’s Billboard

Class Device address is set by the host. Once the timer expires, the

Billboard Class Device will automatically detach from the host and re-

attach as the default WinUSB device.

Increments of 10ms can be set.

Note:

The default value of 413Ch = D0h, 413Dh = 07h is equiv-

alent to a 20s timeout. (07D0h = 2000d)

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