Common control messages, Faders, Switches – Apple Logic Express 7.2 User Manual
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Appendix B
Logic Control—MIDI Implementation
Common Control Messages
Faders
Received:
Ei, ll, hh
Move fader to position
Transmitted:
Ei, ll, hh
Fader moved by user
i
Fader ID (00 thru 07; Master = 08)
ll
Fader position value low 7 bits (00–7F)
hh
Fader position value high 7 bits (00–7F)
Example:
E0, 40, 55 = Fader Ch. 1, position (55 << 7) + 40
Note:
Message
format
for
transmitted
fader
position
is
the
same
as
for
received
position.
Only
the
top
(high)
10
of
the
14
transmitted
bits
are
required.
Positions
0
to
1023
(decimal)
are
transmitted
as
0000
to
03FF
(Ei
00
00
to
Ei
7F
7F).
Switches
Received:
None
Transmitted:
90, ii, ss
Switch pressed/released by user
ii
Switch ID (See “Logic Control—Control Surface Layout and IDs” on page 251.)
ss
Switch
State
00
=
switch
or
fader
relead
7F
=
switch
pressed
or
fader
touched
Example:
90,
0F,
7F
=
SOLO
Ch.
8
is
pressed
90,
0F,
00
=
SOLO
Ch.
8
is
released
Note:
LEDs
and
switches
use
the
same
control
message.
This
approach
means
that
an
LED
has
the
same
ID
as
its
corresponding
switch.
LEDs
Received:
90, ii, ss
Set LED status
Transmitted:
None
ii
LED ID (See “Logic Control—Control Surface Layout and IDs” on page 251.)
ss
LED State (7F = on, 00 = off, 01 = flashing)
Example:
90,
08,
7F
=
Turn
LED
08
on
90,
08,
00
=
Turn
LED
08
off
Note:
Switches
and
LEDs
use
the
same
control
message.
This
ensures
that
an
LED
always
shares
an
ID
with
its
corresponding
switch.