Universal Serial Bus Interface
MCF5253 Reference Manual, Rev. 1
24-152
Freescale Semiconductor
CAUTION
Limiting the number of tracking pipes in the EMBedded
—
TT to four (4) will
impose the restriction that no more than 4 periodic transactions
(INTERRUPT/ISOCHRONOUS) can be scheduled through the
embedded-tt per frame. The number 16 was chosen in the USB specification
because it is sufficient to ensure that the high-speed to full-speed periodic
pipeline can remain full. Keeping the pipeline full puts no constraint on the
number of periodic transactions that can be scheduled in a frame and the
only limit becomes the flight time of the packets on the bus.
— Complete-split transaction searching.
NOTE
There is no data schedule mechanism for these transactions other than the
microframe pipeline. The embedded TT assumes the number of packets
scheduled in a frame does not exceed the frame duration (1 msec) or else
undefined behavior may result.
24.12.1.5.5
Multiple Transaction Translators
The maximum number of embedded Transaction Translators that is currently supported is one as indicated
by the N_TT field in the HCSPARAMS register. See
Section 24.6.2.3, “Host Controller Structural
for more information.
24.12.2 Device Operation
The co-existence of a device operational controller within the USB OTG module has little effect on EHCI
compatibility for host operation. However, given that the controller is initialized in neither host nor device
mode, the USBMODE register must be programmed for host operation before the EHCI host controller
driver can begin EHCI host operations.
24.12.3 Non-Zero Fields the Register File
Some of the reserved fields and reserved addresses in the capability registers and operational registers have
use in device mode, the following must be adhered to:
•
Write operations to all EHCI reserved fields (some of which are device fields in the USB OTG
module) in the operation registers should always be written to zero. This is an EHCI requirement
of the device controller driver that must be adhered to.
•
Read operations by the module must properly mask EHCI reserved fields (some of which are
device fields in the USB OTG module registers).
24.12.4 SOF Interrupt
The SOF interrupt is a free running 125 µsec interrupt for host mode. EHCI does not specify this interrupt,
but it has been added for convenience and as a potential software time base. Note that the free running
interrupt is shared with the device-mode start-of-frame interrupt. See
Summary of Contents for MCF5253
Page 1: ...Document Number MCF5253RM Rev 1 08 2008 MCF5253 Reference Manual...
Page 26: ...MCF5253 Reference Manual Rev 1 xxvi Freescale Semiconductor...
Page 32: ...MCF5253 Reference Manual Rev 1 xxxii Freescale Semiconductor...
Page 46: ...MCF5253 Introduction MCF5253 Reference Manual Rev 1 1 14 Freescale Semiconductor...
Page 62: ...Signal Description MCF5253 Reference Manual Rev 1 2 16 Freescale Semiconductor...
Page 98: ...Instruction Cache MCF5253 Reference Manual Rev 1 5 10 Freescale Semiconductor...
Page 104: ...Static RAM SRAM MCF5253 Reference Manual Rev 1 6 6 Freescale Semiconductor...
Page 128: ...Synchronous DRAM Controller Module MCF5253 Reference Manual Rev 1 7 24 Freescale Semiconductor...
Page 144: ...Bus Operation MCF5253 Reference Manual Rev 1 8 16 Freescale Semiconductor...
Page 176: ...System Integration Module SIM MCF5253 Reference Manual Rev 1 9 32 Freescale Semiconductor...
Page 198: ...Analog to Digital Converter ADC MCF5253 Reference Manual Rev 1 12 6 Freescale Semiconductor...
Page 246: ...DMA Controller MCF5253 Reference Manual Rev 1 14 18 Freescale Semiconductor...
Page 282: ...UART Modules MCF5253 Reference Manual Rev 1 15 36 Freescale Semiconductor...
Page 344: ...Audio Interface Module AIM MCF5253 Reference Manual Rev 1 17 46 Freescale Semiconductor...
Page 362: ...I2 C Modules MCF5253 Reference Manual Rev 1 18 18 Freescale Semiconductor...
Page 370: ...Boot ROM MCF5253 Reference Manual Rev 1 19 8 Freescale Semiconductor...