Information

Universal Serial Bus Interface
MPC8308 PowerQUICC II Pro Processor Reference Manual, Rev. 1
Freescale Semiconductor 13-155
there are counter already present in the design that can count the 10 msec reset pulse to alleviate the
requirement of the software to measure this duration. Therefore, the basic connection is then summarized
as the following:
• [Port Change Interrupt] Port connect change occurs to notify the host controller driver that a device
has attached.
• Software shall write a ‘1’ to the reset the device.
• Software shall write a ‘0’ to the reset the device after 10 msec.
— This step, which is necessary in a standard EHCI design, may be omitted with this
implementation. Should the EHCI host controller driver attempt to write a ‘0’ to the reset bit
while a reset is in progress the write will simple be ignored and the reset will continue until
completion.
• [Port Change Interrupt] Port enable change occurs to notify the host controller that the device in
now operational and at this point the port speed has been determined.
13.9.6.1.2 Port Speed Detection
After the port change interrupt indicates that a port is enabled, the EHCI stack should determine the port
speed. Unlike the EHCI implementation which will re-assign the port owner for any device that does not
connect at High-Speed, this host controller supports direct attach of non-HS devices. Therefore, the
following differences are important regarding port speed detection:
• Port owner is read-only and always reads 0.
• A 2-bit port speed indicator has been added to PORTSC to provide the current operating speed of
the port to the host controller driver.
• A 1-bit high-speed indicator has been added to PORTSC to signify that the port is in HS vs. FS/LS