MIDI Channel Changer/Combiner 16 Switches and LEDS

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Description:

Have you ever needed to change incoming MIDI data from different channels to one specific MIDI output channel? The MIDI Channel Changer/Combiner can be used to combine MIDI channels (1-16) onto a single MIDI output channel. Note that this unit operates via the MIDI IN and OUT sockets only and not through the USB connection.

Operation:

The unit detects the incoming MIDI data, and if it is a MIDI channel command, converts it to a single MIDI channel which corresponds to the switch selection for MIDI channel (1-16). Note that at power-up/reset the unit defaults to MIDI Channel 1.

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.

This unit works in standard MIDI mode with a MIDI Baud rate of 31250. The system will also work with MIDI running status.

Power Supply:

The Arduino UNO and Mega 2560 boards can be powered from the USB socket or via the external power connector. External power can come either from an AC-to-DC adapter or battery. The adapter can be connected by plugging a centre-positive plug with an internal diameter of 2.1mm, an external diameter of 5.5mm and 12mm long, 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 voltage is 9 volts DC, capable of supplying about 1 Amp, which is 9 Watt (W), (Power = Voltage x Current). Note that the power input selection is automatically selected.

MIDI Channel Selection:

The MIDI Channel (1-16) is user selectable via the 16 momentary action switches.

  

 

The 16 switches are organized in a 16 x 1 matrix with 1 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 1 above.

The 16 LEDs are organized in a 16 x 1 matrix with 1 side of all the LEDs being connected to a common 0 volt ground (GND), via their 16 series resistors. The other side of each LED is connected to a separate pin on the Mega board as shown in table 1 above.

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Features:

The MIDI Channel Changer/Combiner 16 Switches and LEDS Encoder unit consists of:

• An assembled, built and tested Arduino board including a suitable pre-programmed microcontroller,
• The MIDI channel (1-16) is user selectable via the 16 switches,
• A LED (1-16) displays the MIDI channel (1-16) selected,
• A 2.1mm power socket, and associated LED,
• A MIDI activity LED,
• An assembled, built and tested MIDI In/Out Board,
• A 150mm wired MIDI 5-pin DIN input socket,
• A 150mm wired MIDI 5-pin DIN output socket,

The MIDI Channel Changer/Combiner 16 Switches and LEDS Encoder unit requires:

• a 9v battery or equivalent DC power source or USB Power,
• 16 Momentary action Single Pole Single Throw (SPST) switches,
• 16 LEDS wired via 16 suitable series resistors (between 220 ohm to 1k ohm).
• Or a combination of 16 switches with internal  LEDS with series resistors

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Resources:

The MIDI Channel Changer/Combiner 16 Switches and LEDS Unit Resources:

• The circuit schematic is available,
• The 16 switches with internal 6 Volt LEDs drawing,
• The 16 switches and LEDs Wiring drawing,
• The MIDI IN/OUT circuit schematic,
• The MIDI IN/OUT wiring is also available.
• The Arduino Mega circuit schematic,
• The Arduino Mega pins,
• The Arduino Mega 18 x 2 connector pins,
• The MIDI Source Code for the Arduino.

There are a number of LED series resistor calculators available on the web including:

• http://www.ohmslawcalculator.com/led-resistor-calculator
• http://www.resistorguide.com/resistor-for-led/

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