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Lexicon
Building the Control Tree
Once the controlling system knows the number of parameters types the system supports, it needs to know
the position of each in the control tree. The Parameter Type message is used to find the location in the
tree of any parameter type. When you want to find out what parameter type is at a particular control
address, you "request" the Parameter Type Message using the Control Address as arguments to the
Request message. The request for a typical Control Address is shown below. Note that the "Num Control
Levels" and the actual Control Address (eg - "Level A value") fields are 16-bit values in a nibble-ized form
with the least significant nibble coming first.
request
——header——
class
F0 06 09 00 06
03 00 02 00 00 00 00 00 00 00 01 00 00 00 F7
"06" is the message class for the request (un-nibble-ized), "03" is the message class you are requesting
(Parameter Type Message), "2" is the number of control levels in the Control Address, "0" is the value of
level 'A' of the Control Address and "1" is the value of level 'B' of the Control Address (or A:0, B:1). This
would be "Chorus" in the following tree fragment:
Control levels ->
A
B
|
|
MPX 1
0 - Program
0 - Pitch
1 - Chorus
...
1 - System
0 - Audio Config
1 - Setup
...
The top of the control tree is a sort of "null" Control Address which doesn't contain any control levels. It
is requested as follows:
request
——header——
class
F0 06 09 00 06
03 00
The message indicates 0 control levels but the MPX 1 responds with the parameter type at the top of the
tree. The parameter types are represented as numbers in the Parameter Type Message which comes
back from the MPX 1. This number (0x0155) is then used as an index into the database of parameter
descriptions created earlier. Building the control tree always starts by requesting the parameter type at
the top of the tree.
Num Control
Level A
levels
value
C
D
E
|
|
|
0 - Detune (M)
0 - Mix
0-100%
1 - Level
2 - Tune
...
0 - Chorus Algorithm
0 - Mix
1 - Level
2 - EQ
Num Control
levels
00 00 00 00 F7
MPX 1 MIDI Implementation Details
Level B
value
F
G
H
|
|
|
I
|
5
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