Texas Instruments MSP53C391, User Manual

Page: 51 / 109

FM Synthesis Format and Commands
B-5 FM Synthesis
BYTE –9,–8 ;CarAmp=107, FmAmp=119
BYTE –8,–7 ;CarAmp=99, FmAmp=112
BYTE –7,–6 ;CarAmp=92, FmAmp=106
BYTE –6,–5 ;CarAmp=86, FmAmp=101
BYTE –5,–4 ;CarAmp=81, FmAmp=97
BYTE –81,–3 ;CarAmp=0, FmAmp=94
B.2.5 Transposition
Two commands are available for transposing the music (i.e., uniformly shifting
the notes to higher or lower frequencies). The ATRNS command adds a specif-
ic amount to the note value. The RTRNS command adds a relative amount to
the note value.
BYTE ATRNS, NUM
Shifts the music NUM semitones from the value as written, for example:
BYTE ATRNS,12
Shifts the music one octave above the music as written.
The RTRNS command is used to shift the music by a cumulative amount, for
example in the following sequence:
BYTE RTRNS,12 ;This will shift the music up by one octave
BYTE RTRNS,12 ;This will shift the music up a second octave
B.2.6 DETUNE
The DETUNE command shifts the frequency of notes on channel two with re-
spect to the frequency of the notes on channel 1.
BYTE DETUNE,5 ;Add 5 to the frequency of channel 5
B.2.7 Adjust Output Volume
The FADER command is used to scale the volume of the notes played.
BYTE FADER, InitialFaderValue,FaderInc
Where:
FADER is the signal that the command is to adjust the output volume
InitialFaderValue is the new sound volume