USB2524 datasheet(14/58 Pages) MICROCHIP

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USB2524

DS00001588B-page 14

 2013 - 2016 Microchip Technology Inc.

6.0

ASSIGNING PORTS

There are two different (OEM selectable) methods of assigning downstream ports to upstream hosts. One method is

with the PRT_ASSIGN[3:0] interface through the use of mechanical switches or by electrical control of the pins via an

external Microcontroller’s GPIO interface. The second method is through the SMBus interface, where the SMBus inter-

face is used to control the switching hub during operation and can switch downstream ports via SMBus commands.

6.1

Port Assign Interface (PRT_ASSIGN[3:0] Pins)

Assigning ports to either of the upstream host controllers can be accomplished through the 4-wire PRT_ASSIGN inter-

face. The PRT_ASSIGN interface has three operating modes. One is called the Embedded Mode, and the other is

Peripheral Mode (with two different electrical “sub” modes; (level triggered or edge triggered).

6.1.1

EMBEDDED MODE:

The four-pin interface (PRT_ASSIGN[3:0]) operates with only three of the four available pins (PRT_ASSIGN3 is dis-

abled in this mode), which enables a user to select one of 8 pre-determined port assignment configurations. There are

8 “default” configurations, or an OEM can customize the configurations through an EEPROM or SMBus code load.

The configuration is determined by Table 6-1, "USB2524 Port Assign Interface (Embedded Mode)".

Note 6-1

H1 = The USB host or hub that is connected to upstream port #1

Note 6-2

H2 = The USB host or hub that is connected to upstream port #2

Note 6-3

UA = Un-Assigned

Note 6-4

X = Don’t Care

Note:

Any change in PRT_ASSIGN pins will be ignored until the USB2524 is out of reset.

Note:

There is a switching delay determined by the Register D0h: Port Interface Delay Timer.

TABLE 6-1:

USB2524 PORT ASSIGN INTERFACE (EMBEDDED MODE)

Port Assign Interface Encoding

Internal Default Configuration

Host Ownership of

Downstream Ports

PRT_ASSIGN

CONFIG

PORT

H1H1

H2H2

H1H1

H2H2

H1H1

H1H2

H2H2

H2H1

H1H1

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