FEDL2250DIGEST-09

OKI Semiconductor

ML2250 family

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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

Voice data area

Usage prohibited area

ML2251

00808 to FFFF

00800 to 00807

ML2252

00808 to 1FFFF

00800 to 00807

ML2253

00808 to 5FFFF

00800 to 00807

ML2254, 22Q54

00808 to 7FFFF

00800 to 00807

ML2256

00808 to BFFFF

00800 to 00807

ML22Q58

00808 to FFFFF

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.

Playback time [sec] =

1.024

(Memory capacity – 16) (Kbit)

Sampling frequency (kHz)

Bit length

(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:

Playback time=

131 (sec)

1.024

(8192 – 16) (Kbit)

16 (kHz)

4 (bit)

The above equation gives the playback time when the phrase control table function is not used.