Texas Instruments MSP53C391, Руководство пользователя

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FM Synthesis Format and Commands
B-3 FM Synthesis
B.2.1 Musical Notes
Musical notes are defined as:
BYTE Notevalue, TimeValue,Duration,Velocity
Where:
Notevalue defines the pitch of the musical note. The valid values for Note-
value are defined in Appendix C. In general, they range from a minimum of
C1 to a maximum of C6. Within each octave, the sequence is: C, Cs or Db,
D, Ds or Eb, E, F, Fs or Gb, G, Gs or Ab, A, As or Bb, B. For example, the C
sharp in the first octave would be written Cs1. This is the same tone as
Db1.
TimeValue defines the duration of the note that is played. The valid values
for TimeValue are defined in Appendix C. The more common values are:
N8 defines an eighth note. N4 defines a quarter note. N2 defines a half
note. N1 defines a whole note.
Duration defines the sum of the TimeValue and any following rest. For ex-
ample, if a quarter note is followed by a quarter note rest, then it would be
coded with a TimeValue=n4 and a Duration=n2.
Velocity is the relative volume of the note. Values range from 0 to 127.
B.2.2 Tempo Control
The tempo of the music is defined as:
BYTE TEMPO,BPM,TimeSig,EnvelopeLen
Where:
TEMPO is the command that indicates a tempo change is being defined.
BPM is the new tempo. The valid values for BPM are defined in Appendix
C. An example is bpm62, which indicates 62 beats per minute.
TimeSig defines the time signature of the songs. TS44 sets the time signa-
ture to 4/4 time.
EnvelopeLen defines the length of the note envelope. ENVOK sets the
envelope length to normal (i.e., lasting for a whole note).
Note:
The tempo should be set in the channel one stream only. The TEMPOSYNC
command should be placed in the same position in the channel two stream.