Oxford Semiconductor, Inc.
USB to Quad Serial Port Bridge Data Sheet
The processor features program control, logical and integer arithmetic
instructions. All instructions are sixteen bits wide, although some
instructions require operands, which may occupy another one or two
words. Several short immediate instructions are available, allowing
operations with small constant operands to fit into a 16-bit instruction.
The processor divide/multiply function contains all the instructions of
the base processor with additional integer divide and multiply
instructions. A signed multiply instruction takes two 16-bit operands
and returns a 32-bit result. A signed divide instruction divides a 32-bit
operand by a 16-bit operand.
Programmable Timers
There are two built-in programmable timers that generate interrupts.
Both timers decrement on every micro-second clock tick and generate an
interrupt when the timer reaches zero. Similarly, a separate watchdog
timer, that can also generate an interrupt on the OXUSB954, is also
provided.
USB
Internal buffer memory in the USB controller is used to buffer data and
USB packets. The memory is accessed by the 16-bit processor and the
serial interface engine (SIE).
USB transactions are automatically routed to the memory buffer, using
pointers and block sizes set up by the processor, which reads data from
the interface, processes and packetizes it. If there is no activity on the
USB for 3 ms, the USB enters a suspend state.
The USB controller transceiver with its differential driver can transmit
and receive serial data at full speed (12 Mbps). While the transceiver
driver is differential, the receiver section comprises a differential receiver
and two single-ended receivers. Internally, the transceiver interfaces to
the SIE; externally it connects to the USB PHY. The USB controller serial
interface provides access to external EEPROMs and can support a variety
of serial EEPROM formats.
Communication and data flow on the USB is implemented using
uniquely-identifiable endpoints, which are the terminals of
communication flow between a USB host and USB devices. The
OXUSB954 supports 10 endpoints, numbered 0 to 9.
DS-0016 Oct 06
External—Free Release
3
OXFORD [ OXFORD SEMICONDUCTOR ]
