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Philips Semiconductors
9.4.6 Get configuration descriptor
9.4.7 Get device descriptor
9.4.8 Get hub descriptor
9.4.9 Get string descriptor (0)
9.4.10 Get string descriptor (1)
9.4.11 Get string descriptor (2)
2
10. I
C-bus interface
10.1 Protocol
9397 750 08958
Product data
The hub returns 25 bytes containing the configuration descriptor (9 bytes, see
Table
11), the interface descriptor (9 bytes, see
(7 bytes, see
Table
13).
The hub returns 18 bytes containing the device descriptor, see
The hub returns 9 bytes containing the hub descriptor, see
The hub returns 4 bytes containing the language ID, see
The hub returns 46 bytes containing the manufacturer name, see
The hub returns 16 bytes containing the product name, see
2
A simple I
C-bus interface is provided in the ISP1122A 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.
2
The I
C-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.
2
The I
C-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.
2
Each device on the I
C-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 I
9398 393 40011.
Rev. 03 — 30 October 2001
ISP1122A
USB stand-alone hub
Table
12) and the endpoint descriptor
Table
Table
14.
Table
15.
Table
Table
15.
2
C-bus and how to use it ., order number
© Koninklijke Philips Electronics N.V. 2001. All rights reserved.
10.
15.
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