Philips Semiconductors ISP1520
Hi-Speed USB hub controller
Product data Rev. 03 — 24 November 2004 16 of 51
9397 750 13701 © Koninklijke Philips Electronics N.V. 2004. All rights reserved.
I2C-bus address: The address of the ISP1520 is given in Tabl e 10.
9.2.2 Architecture of configurable hub descriptors
The configurable hub descriptors can be masked in the internal ROM memory; see
Figure 7. These descriptors can also be supplied from an external EEPROM or a
microcontroller. The ISP1520 implements both the master and slave I2C-bus
controllers. The information from the external EEPROM or the microcontroller is
transferred into the internal RAM during the power-on reset. A signature word is used
to identify correct descriptors. If the signature matches, the content of the RAM is
chosen instead of the ROM.
When the external microcontroller mode is selected and while the external
microcontroller is writing to the internal RAM, any request to configurable descriptors
will be responded to with a Not AcKnowledge (NAK). There is no specified time-out
period for the NAK signal. This data is then passed to the host during the
enumeration process.
The three configuration methods are selected by connecting pins SCL and SDAin the
manner given in Tabl e 11.
Table 10: I2C-bus slave address
MSB Slave address LSB
Bit A7 A6 A5 A4 A3 A2 A1 R/W
Value 00110100/1
The I2C-bus cannot be shared between the EEPROM and the external microcontroller.
Fig 7. Configurable hub descriptors.
MLD711
MICROCONTROLLER SERIAL EEPROM
MASTER/SLAVE
I2C-BUS INTERFACE
signature
match
RAM
(256 bytes)
DESCRIPTOR
GENERATOR
INTERFACE
ROM
(256 bytes)
MUX
HUB CORE
I2C-bus