ML22808 Datasheet, PDF (23/41 Pages) List of Unclassifed Manufacturers – LAPIS Semiconductor ADPCM Algorithm-Based Speech Synthesis LSI

FEDL2280XFULL-04
ML22808/ML22804/Ml22802-XXX
Memory Allocation and Creating Voice Data
The ROM is partitioned into four data areas: voice (i.e., phrase) control area, test area, voice area, and edit ROM
area.
The voice control area manages the ROM’s voice data. It contains data for controlling the start/stop addresses
of voice data for 256 phrases, use/non-use of the edit ROM function and so on.
The test area contains data for testing.
The voice area contains actual waveform data.
The edit ROM area contains data for effective use of voice data. For the details, refer to the section of “Edit
ROM Function.”
No edit ROM area is available unless the edit ROM is used.
The ROM data is created using a dedicated tool.
ROM address (ML22808/ML22804/ML22802-XXX, ML22P808/ML22P804/ML22P802)
0x00000
0x007FF
0x00800
0x00807
0x00808
Voice control area
(Fixed16 Kbits)
Test area
Voice area
Max: 0xFFFFF
Max: 0xFFFFF
Edit ROM area
Depends on creation
of ROM data.
Playback Time and Memory Capacity
The playback time depends upon the memory capacity, sampling frequency, and playback method.
The equation showing the relationship is given below.
The equation below gives the playback time when the edit ROM function is not used.
(Bit length is 2 bits for 2-bit ADPCM2; 4 bits for 4-bit ADPCM2; 8 bits for PCM.)
Example
: Let the sampling frequency be 16 kHz and 4-bit ADPCM2 algorithm. Then the playback time is
approx. 65 seconds, as shown below.
Playback time =
1.024 × (4096 – 16) (Kbit)
16 (kHz) × 4 (bit)
≅ 65 (sec)
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