ISP1122 Ver la hoja de datos (PDF) - Philips Electronics

Número de pieza

componentes Descripción

Lista de partido

ISP1122

Universal Serial Bus stand-alone hub

Philips Electronics 

Philips Semiconductors

ISP1122

USB stand-alone hub

9.4.6 Get configuration descriptor

The hub returns 25 bytes containing the configuration descriptor (9 bytes, see

Table 11), the interface descriptor (9 bytes, see Table 12) and the endpoint descriptor

(7 bytes, see Table 13).

9.4.7 Get device descriptor

The hub returns 18 bytes containing the device descriptor, see Table 10.

9.4.8 Get hub descriptor

The hub returns 9 bytes containing the hub descriptor, see Table 14.

9.4.9 Get string descriptor (0)

The hub returns 4 bytes containing the language ID, see Table 15.

9.4.10 Get string descriptor (1)

The hub returns 46 bytes containing the manufacturer name, see Table 15.

9.4.11 Get string descriptor (2)

The hub returns 16 bytes containing the product name, see Table 15.

10. I2C-bus interface

A simple I2C-bus interface is provided in the ISP1122 to read customized vendor ID,

product ID and some other configuration bits from an external EEPROM. The

interface supports single master operation at a nominal bus speed of 93.75 kHz.

The I2C-bus interface is intended for bidirectional communication between ICs via two

serial bus wires, SDA (data) and SCL (clock). Both lines are driven by open-drain

circuits and must be connected to the positive supply voltage via pull-up resistors.

10.1 Protocol

The I2C-bus protocol defines the following conditions:

• Bus free: both SDA and SCL are HIGH

• START: a HIGH-to-LOW transition on SDA, while SCL is HIGH

• STOP: a LOW-to-HIGH transition on SDA, while SCL is HIGH

• Data valid: after a START condition, data on SDA are stable during the HIGH

period of SCL; data on SDA may only change while SCL is LOW.

Each device on the I2C-bus has a unique slave address, which the master uses to

select a device for access.

The master starts a data transfer using a START condition and ends it by generating

a STOP condition. Transfers can only be initiated when the bus is free. The receiver

must acknowledge each byte by means of a LOW level on SDA during the ninth clock

pulse on SCL.

For detailed information please consult The I2C-bus and how to use it., order number

9398 393 40011.

9397 750 07002

Product specification

Rev. 03 — 29 March 2000

© Philips Electronics N.V. 2000. All rights reserved.

20 of 48

Share Link: