CY7B923
CY7B933
Document #: 38-02017 Rev. *E
Page 7 of 33
possibility of erroneously reframing to an aliased K28.5
character.
Shifter
The Shifter accepts serial inputs from the Serial Data inputs
one bit at a time, as clocked by the Clock Synchronization
logic. Data is transferred to the Framer on each bit, and to the
Decode register once per byte.
Decode Register
The Decode register accepts data from the Shifter once per
byte as determined by the logic in the Clock Synchronization
block. It is presented to the Decoder and held until it is trans-
ferred to the output latch.
Decoder
Parallel data is transformed from ANSI-specified X3.230
8B/10B codes back to “raw data” in the Decoder. This block
uses the standard decoder patterns shown in the Valid Data
Characters and Valid Special Character Codes and
Sequences sections of this datasheet. Data patterns are
signaled by a LOW on the SC/D output and Special Character
patterns are signaled by a HIGH on the SC/D output. Unused
patterns or disparity errors are signaled as errors by a HIGH
on the RVS output and by specific Special Character codes.
Output Register
The Output register holds the recovered data (Q0–7, SC/D, and
RVS) and aligns it with the recovered byte clock (CKR). This
synchronization insures proper timing to match a FIFO
interface or other logic that requires glitch free and specified
output behavior. Outputs change synchronously with the rising
edge of CKR.
In BIST mode, this register becomes the signature pattern
generator and checker by logically converting itself into a
Linear Feedback Shift Register (LFSR) pattern generator.
When enabled, this LFSR will generate a 511-byte sequence
that includes all Data and Special Character codes, including
the explicit violation symbols. This pattern provides a
predictable but pseudo-random sequence that can be
matched to an identical LFSR in the Transmitter. When
synchronized, it checks each byte in the Decoder with each
byte generated by the LFSR and shows errors at RVS.
Patterns generated by the LFSR are compared after being
buffered to the output pins and then fed back to the compar-
ators, allowing test of the entire receive function.
In BIST mode, the LFSR is initialized by the first occurrence of
the transmitter BIST loop start code D0.0 (D0.0 is sent only
once per BIST loop). Once the BIST loop has been started,
RVS will be HIGH for pattern mismatches between the
received sequence and the internally generated sequence.
Code rule violations or running disparity errors that occur as
part of the BIST loop will not cause an error indication. RDY
will pulse HIGH once per BIST loop and can be used to check
test pattern progress. The receiver BIST generator can be
reinitialized by leaving and re-entering BIST mode.
Test Logic
Test logic includes the initialization and control for the Built-In
Self-Test (BIST) generator, the multiplexer for Test mode clock
distribution, and control logic for the decoder. Test logic is
discussed in more detail in the CY7B933 HOTLink Receiver
Operating Mode Description.
HOTLink CY7B923 Transmitter and CY7B933
Receiver Operation
The CY7B923 Transmitter operating with the CY7B933
Receiver form a general purpose data communications
subsystem capable of transporting user data at up to 33
Mbytes per second (40 Mbytes per second for –400 devices)
over several types of serial interface media. Figure 7 illus-
trates the flow of data through the HOTLink CY7B923 trans-
mitter pipeline. Data is latched into the transmitter on the rising
edge of CKW when enabled by ENA or ENN. RP is asserted
LOW with a 60% LOW/40% HIGH duty cycle when ENA is
LOW. RP may be used as a read strobe for accessing data
stored in a FIFO. The parallel data flows through the encoder
and is then shifted out of the OUTx± PECL drivers. The bit-rate
clock is generated internally from a multiply-by-ten PLL clock
generator. The latency through the transmitter is approxi-
mately 21tB – 10 ns over the operating range. A more
complete description is found in the section CY7B923
HOTLink Transmitter Operating Mode Description.
Figure 2 illustrates the data flow through the HOTLink
CY7B933 receiver pipeline. Serial data is sampled by the
receiver on the INx± inputs. The receiver PLL locks onto the
serial bit stream and generates an internal bit rate clock. The
bit stream is deserialized, decoded and then presented at the
parallel output pins. A byte rate clock (bit clock
÷ 10)
synchronous with the parallel data is presented at the CKR pin.
The RDY pin will be asserted to LOW to indicate that data or
control characters are present on the outputs. RDY will not be
asserted LOW in a field of K28.5s except for any single K28.5
or the last one in a continuous series of K28.5’s. The latency
through the receiver is approximately 24tB + 10 ns over the
operating range. A more complete description of the receiver
is in the section CY7B933 HOTLink Receiver Operating Mode
Description.
The HOTLink Receiver has a built-in byte framer that synchro-
nizes the Receiver pipeline with incoming SYNC (K28.5)
characters. Figure 3 illustrates the HOTLink CY7B933
Receiver framing operation. The Framer is enabled when the
RF pin is asserted HIGH. RF is latched into the receiver on the
falling edge of CKR. The framer looks for K28.5 characters
embedded in the serial data stream. When a K28.5 is found,
the framer sets the parallel byte boundary for subsequent data
to the K28.5 boundary. While the framer is enabled, the RDY
pin indicates the status of the framing operation.
When the RF pin is asserted HIGH, RDY leaves it normal
mode of operation and is asserted HIGH while the framer
searches the data stream for a K28.5 character. After the
framer has synchronized to a K28.5 character, the Receiver
will assert the RDY pin LOW when the K28.5 character is
present at the parallel output. The RDY pin will then resume
its normal operation as dictated by the MODE and BISTEN
pins.
The normal operation of the RDY pin in encoded mode is to
signal when parallel data is present at the output pins by
pulsing LOW with a 60% LOW/40% HIGH duty cycle. RDY
does not pulse LOW in a field of K28.5 characters; however,
RDY does pulse LOW for the last K28.5 character in the field
or for any single K28.5. In unencoded mode, the normal
operation of the RDY pin is to signal when any K28.5 is at the
parallel output pins.
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