Figure 79 - The Soundbias Register - Nintendo GAME BOY ADVANCE Programming Manual

May 25, 2005
SOUNDCNT_H [d13],[d09] L Output for Each Direct Sound
Controls the output to L for each direct sound. A setting of 0 results in no output to L; a setting of 1
causes output to L.
SOUNDCNT_H [d12],[d08] R Output for Each Direct Sound
Controls the output to R for each direct sound. A setting of 0 results in no output to R; a setting of 1
causes output to R.
SOUNDCNT_H [d03],[d02] Output Ratio for Each Direct Sound
Selects the output level for each direct sound.
A setting of 0 produces output that is 1/2 of full range. A setting of 1 results in full-range output.
SOUNDCNT_H [d01 - 00] Output Ratio for Synthesis of Sounds 1-4
Specifies the output level for the synthesis of sounds 1-4.
A setting of 00 results in output that is 1/4 of full range.
A setting of 01 results in output that is 1/2 of full range.
A setting of 10 results in full-range output.
A setting of 11 is a prohibited code.
10.8 Sound PWM Control
Bit modulation format PWM is used in the Game Boy Advance sound circuit. When no sound is produced,
the duty waveform is output, and bias voltage is provided. The PWM circuit is stopped when the setting for
duty is 0h.
The bias level uses system ROM. This can be the cause of errors, therefore be careful not to
Note:
change the bias level value.
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
Address Register
SOUND
088h
BIAS
© 1999-2005 NINTENDO
Sound PWM Control
Figure 79 - The SOUNDBIAS Register
Amplitude Resolution/Sampling Cycle
Attributes Initial Value
R/W
0200h
Bias Levels
AGB-06-0001-002-B13
Released: May 27, 2005
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