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36 Switches to MIDI PROGRAM CHANGE

 

MIDI 36 Switches PROGRAM CHANGE 

The MIDI Program Change Commands are usually used to change the sound/voice in a MIDI sound module/synthesiser. However this design uses the MIDI Program Change commands to control a MIDI Video Switcher, the Arkaos Grand VJ which stores and plays video files.

 

This design is for a MIDI Encoder unit with 36 inputs for momentary action switches, a rotary potentiometer to adjust delay between operating switches, A standard MIDI Output socket, A USB serial MIDI Output working in parallel with standard MIDI output. The 36 Program Change commands are associated with 36 switches operating on MIDI Channel 1.  

 

This unit can work in standard MIDI mode and via the USB connection. It defaults to standard MIDI Baud rate of 31250. By replacing the original firmware on Mega8u2/16U2, the Arduino Uno will act as USB-MIDI device (Standard Midi Class), you don’t need to install additional device drivers on Windows, MaxOSX, and Linux, as the firmware acts as a device of Standard Midi Class. It will automatically install on the system as an Audio USB Device  

   

An advantage of using Program Change data, instead of Note on/off commands,  is that you can interface with a lot of MIDI controlled effects units.

 

 

MEGA PCB PINS.jpg (42295 bytes)

 

MIDI 36 Switches

Program Change

ITEM#: MIDI36SWSPROGCHANGE

PRICE:  €70.00


 

*Click to Enlarge*

 

 

 

 

 

 

The MIDI 36 Switches Program Change Unit consists of:

 

  • The unit operates on MIDI channels 1, 
  • An assembled  Arduino MEGA,
  • A 2.1mm power socket, and associated LED, 
  • USB power or external power choice,
  • A MIDI 5-pin DIN output socket,
  • A USB/MIDI socket (For USB serial MIDI use 38400 Baud rate in MIDI software driver),
  • A 10k ohm delay potentiometer, delay is adjustable from 30 milliseconds to 10 seconds,

 

 

The MIDI 36 Switches Program Change unit requires:

  • a 9v battery or equivalent DC power source
  • 36 suitable momentary action switches.

 

Circuit Schematic:

A circuit schematic of the MIDI 36 Switches Program Change unit shows the switch connections. The circuit schematic for the Arduino MEGA is also available.

   

MIDI Wiring:

The MIDI  OUT connection uses a 5-Pin 180 degree DIN sockets. Note that the MIDI OUT wiring is polarised and the correct pins should be used. 

    

OPERATION:

The design produces MIDI Program Change data corresponding to the 36 switches. The original purpose for this design was to use the MIDI Program Change commands to control a MIDI Video Switcher, the Arkaos Grand VJ to store and play the video files, to play different videos associated with each switch/Program Change. 

 

Also the delay potentiometer can be adjusted for a delay from 30 milliseconds to 10 seconds. This can be adjusted to prevent videos being switched too fast by multiple users when the unit is installed in an interactive video exhibition.

 

The delay time is displayed by the onboard LED, which switches ON for half the delay and OFF for half the delay. So for example, if the LED appears ON for 2 seconds then the delay is 4 seconds.

   

The MIDI 36 Switches Program Change Wiring:

 

Switch

DIGITAL PIN

Switch0

8

Switch1

9

Switch2

10

Switch3

11

Switch4

22

Switch5

23

Switch6

24

Switch7

25

Switch8

26

Switch9

27

Switch10

28

Switch11

29

Switch12

30

Switch13

31

Switch14

32

Switch15

33

Switch16

34

Switch17

34

Switch18

36

Switch19

37

Switch20

38

Switch21

39

Switch22

40

Switch23

41

Switch24

42

Switch25

43

Switch26

44

Switch27

45

Switch28

46

Switch29

47

Switch30

48

Switch31

49

Switch32

50

Switch33

51

Switch34

52

Switch35

53

 

The 36 switches (Switch0 to Switch35) are organized in a 36 x 1 matrix with one side of all the switches being connected to a common 0 volt ground (GND). The other side of each switch is connected to a separate pin on the Mega board as shown in table above.

 

Power Supply:

The  Arduino MEGA can be powered via the USB connection or with an external power supply. The power source is selected automatically. 

 

External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or battery. The adapter can be connected by plugging a 2.1mm center-positive plug into the board's power jack. Leads from a battery can be inserted in the Gnd and Vin pin headers of the POWER connector. A low dropout regulator provides improved energy efficiency.

 

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.