MA1916 Datasheet, PDF (4/11 Pages) Dynex Semiconductor – Radiation Hard Reed-Solomon & Convolution Encoder

MA1916
SMC_OUT (Select Message or Checksum)
This output signal is held high while the test generator clocks
out a data packet on the MSG_OUT pin. When the packet is
complete this signal goes low. It is held low for a period equal to
the time required by the RS encoder to send the corresponding
checksum. When this is complete the signal goes high and the
test generator begins a new data packet. This signal can be
connected directly to SMC for testing purposes.
READY (Test Data Valid)
This output is held low during reset and remains low for the
first complete cycle of SMC_OUT. READY rises on the second
rising edge of SMC_OUT and remains high to indicate the
presence of valid data on MSG_OUT.
CLKS (Synchronisation Clock)
This output clock runs at half the speed of the input clock
CLK. CLKS remains low after n_RST is raised until SMC is
raised, SMC being captured on the falling edge of CLK (timing
4). CLKS then changes state on the rising edge of each CLK
cycle regardless of the state of SMC. The signal is used to
clock data into and out of the RS encoder.
Figure 4: Reed-Solomon Encoder
ST1 (RS Encoder Output Valid)
This output is set low during a reset and goes high when
sufficient dummy data has been clocked through the RS
encoder to clear it (see Figure 5).
SYZ (Byte Rate Clock)
SYZ is a byte rate clock output derived from CLKS. It is
high during every eighth period of CLKS and low at other
times.
MSG (Message)
MSG is the data input to the RS encoder. Each bit is read in
on the rising edge of CLKS. While the SMC signal is high data
on the input passes directly to the output RSE_OUT. While
SMC is low RSE_OUT is the logical XOR of the MSG input and
the output of the check-sum generator. Therefore MSG must
be held low while the RS encoder is clocking out the check
sum (see Figure 4).
SZY (Byte Rate Clock)
SZY is a byte rate clock output derived from CLKS. It is low
during every eighth period of CLKS and high at other times. It
is the inverse of SYZ.
ST2 (Production Test Output)
The output is used for production testing and should be left
unconnected.
SMC (Select Message or Checksum)
While the SMC input is high, data on the MSG pin is
clocked into the RS encoder. SMC is held high for a period
dictated by the interleave depth being used (see Table 1).
When SMC falls the RS encoder begins to clock out the
checksum for the preceeding data. SMC should be held low
until the complete checksum has been output. The rising edge
of SMC indicates the start of a new data block to be encoded.
TEST_POINT (Production Test Output)
This output is used for production testing and should be left
unconnected.
CE_IN (Convolution Encoder Data In)
This input is used to read data into the convolution
encoder. The state of CE_IN is read on the rising edge of
CE_CLK.
RSE_OUT (Reed-Solomon Encoder Output)
This signal outputs the completed data packet comprised
of the message followed by its associated checksum block.
The data is valid on the rising edge of CLKS.
n_RST
SMC
MSG
CLKS
ST1
Output Valid
Note: ST1 rises on the second rising edge of SMC following n_RST high.
CLKS starts toggling on the first rising edge of SMC following n_RST high.
Figure 5: Reed-Solomon Encoder Operation
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