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Universal Serial Bus Specification Revision 1.1

11.4 Internal Port

The internal port is the connection between the Hub Controller and the Hub Repeater. Besides conveying the serial data to/from the Hub Controller, the internal port is the source of certain resume signals. Figure 11-5 illustrates the internal port state machine; Table 11-2 defines the internal port signals and events.

!Rx_Suspend

Inactive

! = Logical NOT

Rx_Suspend

Suspend Delay

EOI

Fsus

Resume_Event

GResume

Figure 11-5. Internal Port State Machine

Table 11-2. Internal Port Signal/Event Definitions

Signal/Event Name

Event/Signal

Description

 

Source

 

 

 

 

EOI

Internal

End of timed interval

 

 

 

Rx_Suspend

Receiver

Receiver is in the Suspend state

 

 

 

Resume_Event

Hub Controller

A resume condition exists in the Hub Controller

 

 

 

11.4.1 Inactive

This state is entered whenever the Receiver is not in the Suspend state.

11.4.2 Suspend Delay

This state is entered from the Inactive state when the Receiver transitions to the Suspend state. This is a timed state with a 2ms interval.

11.4.3 Full Suspend (Fsus)

This state is entered when the Suspend Delay interval expires.

237

Universal Serial Bus Specification Revision 1.1

11.4.4 Generate Resume (GResume)

This state is entered from the Fsus state when a resume condition exists in the Hub Controller. A resume condition exists if the C_PORT_SUSPEND bit is set in any port or if the hub is enabled as a wakeup source and any bit is set in a Port Change field or the Hub Change field (as described in Table 11-14 and Table 11-10, respectively).

In this state, the internal port generates signaling to emulate an SOP_FD to the Hub Repeater.

238

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