The MIDI Program Change Commands can change the sound/voice in a MIDI sound module/synthesiser. There are 4 momentary action switch inputs which can work in parallel with momentary action foot-pedals. An advantage of using Program Change data is that you can interface with a lot of MIDI controlled effects units. The 4 switches can increment/decrement the Program Change value, from 1 to 128, in steps of +1, -1, +10 or -10.
The MIDI signal is also looped from the MIDI IN socket to the MIDI OUT socket so data can be looped through a number of other MIDI units.Operation:
The unit detects the incoming MIDI data and passes it unchanged to the MIDI Output. However a Program Change command can also be transmitted whenever any of the 4 momentary action switches are pressed, on the MIDI channel which corresponds to the DIP switch MIDI channel (1-16) setting.
If any System Common, Realtime or Exclusive events are detected they are passed directly from the input to the output. System Exclusive messages will be sent until the End of System Exclusive message is received. However if a system realtime message is received during a System Exclusive message it is also passed to the output.Power Supply:
External power can come either from an AC-to-DC adapter or battery. The adapter can be connected by plugging a 2.1mm center-positive plug into the board's power jack.
The board can operate on an external supply of 7 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may be unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts.MIDI Channel Selection:
The MIDI Program Change commands are all channel (1-16) dependent. The system will also work with MIDI running status.
Table 1 MIDI Channel
The MIDI Program Change Unit requires: