FEDL2280XDIGEST-03
OKI Semiconductor
ML22808/ML22804/ML22802-XXX
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.
1.024 × (4096 – 16) (Kbit)
16 (kHz) × 4 (bit)
Playback time =
≅ 65 (sec)
Edit ROM Function
The edit ROM function makes it possible to play back multiple phrases in succession. The following functions
are set using the edit ROM function:
• Continuous playback:
There is no limit to the number of times a continuous playback can be
specified. It depends on the memory capacity only.
20 to 1024 ms
• Silence insertion function:
Using the edit ROM function enables an effective use of the memory capacity of voice ROM.
Memory Bank Selecting Function
Using the memory bank selecting function, the internal ROM area in the ML22808/ML22804/ML22P808/
ML22P804 can be divided into up to four areas. If four banks are used, up to 1024 phrases can be played
back since each bank is capable of up to 256 phrases. Using the memory bank selecting function, the internal
ROM area in the MLl22802/ML22P802 can be divided into up to two areas. If two banks are used, up to 512
phrases can be played back because each bank is capable of up to 256 phrases. Using this function, it is
possible to put together multiple ROM codes into one code.
In the case of the ML22808/ML22804/ML22P808/ML22P804, the memory is used by setting the SEL1 and
SEL0 pins and in the case of the ML22802/ML22P802, the memory is used by setting the SEL pin, as shown in
the tables below. In addition, when playing phrases, it is necessary to specify the number of memory banks by
PUP1 or PUP2.
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