UHC124 Datasheet, PDF (3/6 Pages) List of Unclassifed Manufacturers – High Performance Four-Port Embedded USB Host Controller

Product Brief
TransDimension
UHC124
activity. This problem is more obvious and damaging when data packet sizes are small and spontaneous,
which is typical for many embedded USB host applications, making double buffering impractical.
• waste MCU’s time due to processor/RTOS overhead with frequent ISR invocation and execution.
With its batch processing capability, a single register write to the UHC124 can dispatch altogether up to 16
transactions, and a single interrupt is generated only after the completion of all of them. The system throughput is
therefore significantly improved maximizing the bandwidth on the USB. At the same time, the number of interrupts
to the MCU is greatly reduced, saving processor resources for non-USB activities.
Double Buffering: Double buffering, and its more general form circular buffering, are effective ways to improve
the USB system throughput. The UHC124 supports dual port memory access to its entire addressing space
(control registers, CM and DM). Together with its batch processing capability, double buffering becomes attractive
even for transactions with small data packets.
Root Hub: The UHC124 employs a fully qualified, market proven 4-port USB hub. Analog USB transceivers are
built-in for all four downstream ports. Power-on and over-current circuits are presented individually for each port.
External Crystal/Oscillator: A PLL (Phase Locked Loop) is integrated on-chip to generate, from a single 6 MHz
crystal or crystal oscillator, the 48 MHz, 12 MHz and 6 MHz clock signals required by the UHC124 internal circuitry
minimizing EMI.
UHCI and OHCI: The UHC124 is fully compliant with USB Specification 2.0 (for full speed and low speed
operation). However, it is not a Universal Host Controller Interface/Open Host Controller Interface (UHCI/OHCI)
based device because it is not intended for the PCI bus. OEMs may develop or license, a Host Controller Driver
(HCD) providing a software interface that appears to the rest of the USB host stack as if there were a UHCI or an
OHCI compliant host controller.
System Suspend and Resume: Under the control of user software, the UHC124 may bring the USB system into
suspend state, as dictated by USB specification. While the oscillator for the UHC124 is still running, all USB bus
activities, including SOF generation, are stopped. The system may be brought out of the suspend state by user
software, or by a remote wakeup originating from a downstream USB device.
Power Saving Mode: Under the control of user software, the UHC124 may enter the power saving mode, in which
all internal clocks are stopped, and the PLL is disabled. A small quiescent current (about 200 uA) is consumed by
the UHC124. The UHC124 is reactivated by a hardware reset.
Software Support: TransDimension is a leader in the embedded market space, bringing both software and silicon
to its customers. USB Host Stack, device drivers for most products, and interface code to the UHC124 for
numerous RTOS’ are available via our wholly owned subsidiary, SoftConnex Technologies, Inc. The products are
geared towards mobile and post-PC products, including mobile phone, palmtop PC, PDA, set top box, home
gateway, and Internet appliances.
TransDimension provides development and support packages and a wide spectrum of USB host software support
in C source code to reduce development cost and time to market for its customers. USB Stack software for various
real-time operating systems and device drivers for most mobile and post-PC products, as well as required interface
code between the USB stack and the silicon are available by contacting your local TransDimension representative.
OEMs may license from TransDimension, as part of the UHC124 Development Kit, an OS-independent UHC124
Programming Interface Library, supporting direct UHC124 operation and efficient USB host control independent of
any RTOS. The UHC124 USB Host Controller Exerciser allows an OEM to quickly evaluate, and to develop
applications for the UHC124 to operate on USB devices.
TransDimension Inc. — Proprietary
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