Philips ISP1520 사용자 설명서
Philips Semiconductors
ISP1520
Hi-Speed USB hub controller
Product data
Rev. 03 — 24 November 2004
15 of 51
9397 750 13701
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
The detection of any non-removable port sets the hub descriptor into a compound
hub.
hub.
9.1.5
Port indicator support
The port indicator support can be disabled by grounding all green port indicators (all
pins GRNn_N); see
pins GRNn_N); see
. This is a global feature. It is not possible to disable port
indicators for only one port.
9.2 Device descriptors and string descriptors settings using I
2
C-bus
9.2.1
Background information on I
2
C-bus
The I
2
C-bus is suitable for bi-directional communication between ICs or modules. It
consists of two bi-directional 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.
Both these lines must be connected to a positive supply voltage through a pull-up
resistor.
The basic I
2
C-bus protocol is defined as:
•
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.
the clock is HIGH. Any changes in data lines when the clock is HIGH will be
interpreted as control signals.
Different conditions on I
2
C-bus:
The I
2
C-bus protocol defines the following
conditions:
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 HIGH period of SCL.
Data transfer:
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 acknowledgement is done by
pulling the SDA line LOW on the ninth bit of the data. An extra clock pulse needs to
be generated by the master to accommodate this bit.
byte of data must be acknowledged by the receiver. The acknowledgement is done by
pulling the SDA line LOW on the ninth bit of the data. An extra clock pulse needs to
be generated by the master to accommodate this bit.
For more detailed information on the operation of the bus, refer to
The I
2
C-bus
specification.
Table 8:
Non-removable port pin configuration
AMBn_N (n = 1 to 4)
Non-removable port
Ground
non-removable
Pull-up with amber LED
removable
Table 9:
Port indicator support: pin configuration
GRN1_N to GRN4_N
Port indicator support
Ground
not supported
LED pull-up green LED for at least one port
supported