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SCSP User's Manual/4.2 Sound source register

■Volume register

TL[7:0](R/W) ; Total Level
The actual attenuation amount [dB] is the sum of the attenuation amounts for the bits set to "1B" out of the total level 8 bits. Therefore, the larger the value set for "TL", the greater the attenuation and the lower the volume. Conversely, the smaller the value set for TL, the smaller the amount of attenuation and the higher the volume.

For example, the amount of attenuation when writing "FFH" is


- 48 - 24 - 12 - 6 - 3 - 1.5 - 0.8 - 0.4 = -95.7[dB]

It becomes.

Table 4.18 TL, attenuation and waveform amplitude
 TL bit
 bit 7
 bit 6
 bit 5
 bit 4
 bit 3
 bit 2
 bit 1
 bit 0
 TL attenuation
 -48 -24 -12 -6 -3 -1.5 -0.8 -0.4
 amplitude ratio
 1/256 1/16 1/4 1/2 1/√2 1/4 √2 1/8 √2 1/ 16 √2
 Real number ratio (times)
 0.00391 0.06250 0.25000 0.50000 0.70711 0.84090 0.91700 0.95760

Also, if bit 4 is set to "1B", the amplitude of the output waveform after TL calculation will be 1/2 of the amplitude in the waveform memory, as shown in Figure 4.50.

Figure 4.44 Wave data when TL bit4=1

SDIR(R/W) ; Sound DIRect
This is a flag to determine whether to directly output sound data. When this bit is "1B", the sound data is output without being multiplied by EG, TL, ALFO, etc.

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