isp1521 NXP Semiconductors, isp1521 Datasheet - Page 16

• Manufacturer Part Number: isp1521
• Description: Hi-speed Universal Serial Bus Hub Controller
• Manufacturer: NXP Semiconductors

Philips Semiconductors
ISP1521_4
Product data sheet
8.2.1.1 Different conditions on I
8.2.1.2 Data transfer
8.2.1.3 I
8.2.1 Background information on I
8.2 Device descriptors and string descriptors settings using I
Table 9.
The I
consists of two bidirectional lines: SDA for data signals, and SCL for clock signals. Both
these lines must be connected to a positive supply voltage through a pull-up resistor.
The basic I
The I
Not busy — both SDA and SCL remain 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 must be stable for the duration of the
HIGH period of SCL.
The master initiates each data transfer using a START condition and terminates it by
generating a STOP condition. To facilitate the next byte transfer, each byte of data must be
acknowledged by the receiver. The acknowledgment is done by pulling the SDA line LOW
on the ninth bit of the data. An extra clock pulse must be generated by the master to
accommodate this bit.
For details on the operation of the bus, refer to The I2C-bus specification .
The address of the ISP1521 is given in
Table 10.
GRN1_N to GRN7_N
Ground
LED pull-up green LED for at least one port
2
Bit
Value
•
•
C-bus address
Data transfer is initiated only when the bus is not busy.
Changes in the data line occur when the clock is LOW, and must be stable when the
clock is HIGH. Any changes in data lines when the clock is HIGH will be interpreted as
control signals.
2
2
C-bus is suitable for bidirectional communication between ICs or modules. It
C-bus protocol defines the following conditions:
Port indicator support: pin configuration
I
MSB
A7
0
2
2
C-bus protocol is defined as:
C-bus slave address
Slave address
A6
0
Rev. 04 — 30 March 2006
2
C-bus
A5
1
2
C-bus
Table
A4
1
Port indicator support
not supported
supported
10.
A3
0
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Hi-Speed USB hub controller
A2
1
LSB
A1
0
ISP1521
2
C-bus
Write
0
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