of Microprocessors

ORGAN KEYBOARD INTERFACE
315
Table 9-1. MIDI Command Summary
Command Bytes
1001cccc
Okkkkkkk
Owvvwv
1000cccc
Okkkkkkk
Owvvvw
1010cccc
Okkkkkkk
Oppppppp
1101 cccc
Oppppppp
1011cccc
Oddddddd
Ovwvwv
1110ccc
Ohhhhhhh
01111111
1100cccc
Oppppppp
Description
NOTE ON EVENT. cccc = 4-bit channel number. kkkkkkk = 7-bit key
number where 60 (decimal) is middle C. vwvvvv = 7-bit key-down
velocity where 0 is slow and 127 is fast. Use 64 if the keyboard is not
velocity sensitive.
NOTE OFF EVENT. cccc and kkkkkkk fields are as for NOTE On.
vvvvvvv = 7-bit key-up velocity.
NOTE PRESSURE UPDATE. cccc and kkkk fields are as for Note
On. ppppppp = 7-bit pressure value for key kkkkkkk, 0 is light and
127 is heavy. This command is sent every 10-50 msec. It need not
be sent if the keyboard has no pressure sensors.
CHANNEL PRESSURE UPDATE. Used in mono mode. Updates the
pressure parameter in voice cccc. ppppppp is as for Note Pressure
Update.
CONTROL CHANGE. Used to change internal variables of
synthesizer listening to channel cccc. ddddddd is 7-bit device
(control) number as follows:
0-31 wvwvv is most significant 7 bits of value for control numbers
0-31.
32-63 vvvwvv is least significant 7 bits of value for control numbers
0-31.
64-95 vvwwv is state (0 = off, 127=on) of switch numbers 0-31.
96-127 miscellaneous synthesizer commands including mode
(mono/poly/mono) select. wvvvvv is ignored but must be
present.
PITCH WHEEL CHANGE. Used to change internal pitch wheel
variable of synthesizer listening to channel cccc. hhhhhhh is most
significant 7 bits of the new value and 1111111 is least significant 7
bits.
PATCH CHANGE. Specifies that synthesizer listening to channel cccc
should change to "patch" ppppppp. This is of course highly
synthesizer dependent.
"status byte" in the standards document) followed by zero or more data bytes
(Table 9-1). The command byte is always identified by having its most
significant bit set to a one, while data bytes always have a zero there.
Although this convention limits data values to 0-127 or - 64 to + 63, it
completely prevents a permanent "out-of-sync" condition if a byte should be
lost somewhere or an erroneous command code is received. In cases in which
increased resolution is needed, two data bytes can be used to express values
up to 16,383 or - 8,192 to + 8, 191. Table 9-1 gives a brief summary of the
commands and data formats useful in a keyboard interfacing situation. Note
that in most cases, the most significant 3 bits of the command give the
command code, while the least significant 4 bits is the channel address. The
F command, which is not listed, provides for the transmission of systemdependent
data that vary for different manufacturers.