AGB Programming Manual
Sound
©1999 - 2001 Nintendo of America Inc.
95
D.C.N. AGB-06-0001-002B4
SOUND3CNT_X [d14] Sound Length Flag
When 0, sound is continuously output.
When 1, sound is output for only the length of time specified for the sound
length in NR31.
When sound output ends, the Sound 2 ON flag of NR52 is reset.
SOUND3CNT_X [d10 - 00] Frequency Data
With fdat signifying the frequency, the output frequency (f) is determined by
the following formula.
Hz
fdat
f
)
2048
(
2
4
4194304
3
−
×
×
=
Thus, the specifiable range of frequencies is 64 to 131.1 KHz.
[Sound 3 Usage Note]
1.
When changing the frequency during Sound 3 output, do not set the initialization
flag. The contents of waveform RAM may be corrupted. With sounds 1, 2 , and 4,
the initialization flag can be set without problems.
2.
For sound 3, if you change the frequency when selecting a consecutive
operation mode (Reset the sound length flag of NR34), always set 0 for the
data of sound length (NR31) after setting the frequency data. If 0 is not set,
sound may stop prematurely.