USB2640 datasheet(23/60 Pages) MICROCHIP

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DS00001947C-page 23

USB2640/USB2641

7.0

CONFIGURATION OPTIONS

7.1

Hub

Microchip’s USB 2.0 hub is fully compliant to the Universal Serial Bus Specification available from the USB Imple-

menter’s Forum found at http://www.usb.org (Revision 2.0 April 27, 2000 and the 12/7/2000 and 5/28/2002 Errata).

Please reference Chapter 11 (Hub Specification) for general details regarding hub operation and functionality.

The hub provides 1 transaction translator (TT) that is shared by both downstream ports (defined as a single-TT config-

uration). The TT contains 4 non-periodic buffers.

7.1.1

HUB CONFIGURATION OPTIONS

The Microchip hub supports a large number of features (some are mutually exclusive), and must be configured in order

to correctly function when attached to a USB host controller. There are two principal ways to configure the hub:

• via the internal default settings or

• by settings stored in an external EEPROM or SPI Flash device.

7.1.1.1

Power Switching Polarity

The hub only supports active high port power controllers.

7.1.2

VBUS DETECT

According to Section 7.2.1 of the USB 2.0 Specification, a downstream port cannot provide power to its D+ or D- pull-

up resistors unless the upstream port’s VBUS is in the asserted (powered) state. The VBUS_DET pin on the hub mon-

itors the state of the upstream VBUS signal and will not pull-up the D+ resistor if VBUS is not active. If VBUS goes from

an active to an inactive state (not powered), the hub will remove power from the D+ pull-up resistor within 10 seconds.

7.2

Card Reader

The Microchip USB2640/USB2641 is fully compliant with the following flash media card reader specifications:

• Secure Digital 2.0 / MultiMediaCard 4.2

- SD 2.0, HS-SD, HC-SD

- TransFlash™ and reduced form factor media

- 1/4/8 bit MMC 4.2

• Memory Stick 1.43

• Memory Stick Pro Format 1.02

• Memory Stick Pro-HG Duo Format 1.01

- Memory Stick, MS Duo, HS-MS, MS Pro-HG, MS Pro

• Memory Stick Duo 1.10

• xD-Picture Card 1.2 compliant

7.3

System Configurations

7.3.1

EEPROM/SPI INTERFACE

The USB2640/USB2641 can be configured via a 2-wire (I2C) EEPROM (256x8 or a recommended 512x8 for internal

ROM support) or an external SPI ROM flash device containing the firmware for the USB2640/USB2641. If an external

configuration device does not exist, the internal default values will be used. If one of the external devices is used for

configuration, the OEM can update the values through the USB interface. The hub will then “attach” to the upstream

USB host.

When using an external SPI Flash, the register addresses in the following three tables (Table 7-1, Table 7-2, Table 7-3)

refer to offsets from the starting location ‘FE80h’.

The USBDM tool set is available in the USB264x Hub Card reader combo software release package. To download the

software package from Microchip’s website, please visit:

http://www.microchip.com/SWLibraryWeb/producttc.aspx?product=USBDM%20Tool

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