GL850 datasheet(17/40 Pages) ETC

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GL850 USB 2.0 4-Port HUB Controller

Page 17

5.1.9 REPEATER

Repeater logic implements the control logic defined in section 11.4 and section 11.7 of USB specification

Revision 2.0. REPEATER controls the traffic flow when upstream port and downstream port are signaling

in the same speed. In addition, REPEATER will generate internal resume signal whenever a wakeup event

is issued under the situation that hub is globally suspended.

5.1.10 TT (Transaction Translator)

TT implements the control logic defined in section 11.14 ~ 11.22 of USB specification Revision 2.0. TT

basically handles the unbalanced traffic speed between the USPORT (operating in HS) and DSPORTS

(operating in FS/LS) of hub. GL850 adopts the single TT architecture to provide the most cost effective

solution. Single TT shares the same buffer control module for each downstream port.

5.1.11 REPEATER/TT routing logic

REPEATER and TT are the major traffic control machines in the USB2.0 hub. Under situation that

USPORT and DSPORT are signaling in the same speed, REPEATER/TT routing logic switches the traffic

channel to the REPEATER. Under situation that USPORT is in the high speed signaling and DSPORT is in

the full/low speed signaling, REPEATER/TT routing logic switches the traffic channel to the TT.

5.1.11.1 Connected to 1.1 Host/Hub

If an USB2.0 hub is connected to the downstream port of an USB1.1 host/hub, it will operate in USB1.1

mode. For an USB1.1 hub, both upstream direction traffic and downstream direction traffic are passing

through REPEATER. That is, the REPEATER/TT routing logic will route the traffic channel to the

REPEATER.

USB1.1 HOST/HUB

REPEATER

DSPORT operating

in FS/LS signaling

USPORToperating

in FS signaling

Traffic channel

is routed to

REPEATER

Figure 5.1 - Operating in USB1.1 scheme

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