SM5904BF Nippon Precision Circuits Inc, SM5904BF Datasheet - Page 22

• Manufacturer Part Number: SM5904BF
• Description: compression and non compression type shock-proof memory controller
• Manufacturer: Nippon Precision Circuits Inc

Shock-proof operation overview
- Encode sequence
1. Input data from a signal processor IC is stored in
internal buffers.
2. Encoder starts after a fixed number of data have
been received.
- Decode sequence
1. Reads compressed data stored in external buffer
RAM at rate fs.
2. Decoder starts, using the predicting filter type
and quantization levels used when encoded.
- Compare-connect sequence
1. Encoding immediately stops when either external
buffer RAM overflows or when a CD read error
occurs due to shock vibrations.
2. Then, using microcontroller command 80H, the
compare-connect start command is executed and
compare-connect sequence starts.
Shock-proof mode is the mode that realizes shock-
proof operation using DRAM. Shock-proof mode is
invoked by setting MSON=H in microcontroller
SM5904BF
3. The encoder, after the most suitable predicting
filter type and quantization steps have been deter-
mined, performs ADPCM encoding and then writes
to DRAM.
command 80H.
This mode comprises the following 3 sequences.
3. Performs attenuation operation (including muting
operation)
4. Outputs the result.
3. Compares data re-read from the CD with the pro-
cessed final valid data stored in RAM (confirms its
correctness).
4. As soon as the comparison detects conforming
data, compare-connect sequence stops and
encode sequence re-starts, connecting the data
directly behind previous valid data.
NIPPON PRECISION CIRCUITS-22