FEDL2250DIGEST-09
OKI Semiconductor
ML2250 family
Built-in ROM Usage Prohibited Area
(Applies to ML2251/52/53/54/56-XXX, ML22Q54/Q58)
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 (AR207) when
creating the ROM data.
Table below lists the addresses prohibited for use in every ROM model.
Model
ML2251
Voice data area
00808 to FFFF
00808 to 1FFFF
00808 to 5FFFF
00808 to 7FFFF
00808 to BFFFF
00808 to FFFFF
Usage prohibited area
00800 to 00807
00800 to 00807
00800 to 00807
00800 to 00807
00800 to 00807
00800 to 00807
ML2252
ML2253
ML2254, 22Q54
ML2256
ML22Q58
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 is 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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