FEDL2250DIGEST-01
OKI Semiconductor
ML2252/54-XXX, ML22Q54
Built-in ROM Usage Prohibited Area
(Applies to ML2252/54-XXX, ML22Q54)
The 8 bytes between the voice control area and the voice area in the ROM is the prohibited area for use.
The voice data are stored automatically behind 00808(HEX) address by using the development tool (AR762,
AR203, AR204) when creating the ROM data.
Table below lists the addresses prohibited for use in every ROM model.
Model
ML2252
Voice data area
00808 to 1FFFF
00808 to 7FFFF
Usage prohibited area
00800 to 00807
ML2254, 22Q54
00800 to 00807
Note: The addresses are indicated in hexadecimal notation.
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.
1.024 × (Memory capacity – 16) (Kbit)
Sampling frequency (kHz) × Bit length
Playback time [sec] =
(Bit length is ADPCM, ADPCM 2 = 4 bits; PCM = 8 bits.)
Example: Let the sampling frequency be 16 kHz and 4-bit ADPCM algorithm. If one 8 Mbits ROM is used, then
the playback time is obtained as follows:
1.024 × (8192 – 16) (Kbit)
Playback time =
131 (sec)
16 (kHz) × 4 (bit)
The above equation gives the playback time when the phrase control table function is not used.
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