SM5903CF Datasheet, PDF (23/31 Pages) Nippon Precision Circuits Inc – compression and non compression type anti-shock memory controller

SM5903CF
Compare-connect sequence
The SM5903CF supports three kinds of connect
modes; 3-pair compare-connect, 2-pair compare-
connect and direct connect.
Note that the SM5903CF can also operate in 12-bit
comparison connect mode using only the most sig-
nificant 12 bits of data for connection operation.
In 3-pair compare-connect mode, the final 6 valid
data (3 pairs of left- and right-channel data input
before encode processing) and the most recently
input data are compared until three continuous data
pairs all conform. At this point, the encode
sequence is re-started and data is written to VWA.
In 2-pair compare-connect mode, comparison
occurs just as for 3-pair comparison except that
only 2 pairs from the three compared need to con-
form with the valid data. At this point, the encode
sequence is re-started and data is written to VWA.
In direct-connect mode, comparison is not per-
formed at all, and encode sequence starts and data
is written to the VWA. This mode is for systems that
cannot perform compare-connect operation.
- Compare-connect preparation time
1. Comparison data preparation time
Internally, when the compare-connect start com-
mand is issued, a sequence starts to restore the
data for comparison. The time required for this
preparation after receiving the command is approxi-
mately 2.5 × (1/fs). (approximately 60 µs when fs =
44.1 kHz)
2. After the above preparation is finished, data is
input beginning from the left-channel data and com-
parison starts.
3. If the compare-connect command is issued
again, the preparation time above is not necessary
and operation starts from step 2.
4. The same sequence takes place in direct-con-
nect mode also. However, at the point when 3
words have been input, all data is directly connect-
ed as if comparison and conformance had taken
place.
- Compare-connect sequence stop
If a compare-connect stop command (80H with
MSDCN1= 1, MSDCN2= 0) is input from the micro-
controller, compare-connect sequence stops.
If compare-connect sequence was not operating,
the compare-connect stop command performs no
operation. However, make sure that the other bit
settings within the same 80H command are valid.
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