MIDI to 24 Outputs

This unit can be combined with the 4 or 8 MIDI Relay or the 4 or 8-way changeover relay units.

The MIDI to 24 Outputs unit utilizes:

• A Printed Circuit Board (PCB), 
• A pre-programmed 16F877 PIC,
• A PCB screw terminal power socket, and associated LED, and 9v battery connector
• A 4-way DIP switch which selects the MIDI channel at power-on, or in programme mode, shown in table 1
• A MIDI 5-pin DIN input socket,
• 24 screw-terminal outputs,
• Outputs (0-23) are programable from first  MIDI note on/off command, 
• The circuit schematic is available in GIF format,
• The circuit layout is also available.
• A programme mode switch and associated LED

The MIDI to 24 outputs also requires:

• A 9v battery or equivalent DC power source

Operation:

1) Normal Mode

2) Programme Mode

Normal Mode:

The unit detects the incoming MIDI data and if the MIDI channel corresponds to the DIP switch MIDI channel setting, when a corresponding Note-on is detected, (to the pre-set note-on  data), the corresponding output is switched on (+5 Volts) and stays on until the corresponding note-off is detected and the output is switched off (0 Volts). This allows each output to operate independently. 

Programme Mode:

At power-up, when switching on the unit, if the programme switch is pressed and held on, then the unit will enter programme mode, and the programme LED is lit. 

Now the first  Note-on command from a MIDI keyboard or sequencer is detected and stored in the EEPROM. This note is the first of 24 consecutive note values, associated with outputs 0 to 23. 

After the Note-on is detected the unit goes into normal operating mode, and the programme LED is off. So the 24 outputs can be programmed to operate consecutively from only the first Note-on command detected. 

Purpose:

The MIDI to 24 output unit can be operated live in real time from a MIDI keyboard or from a hardware/software sequencer with pre-programmed MIDI Note on/off data. The outputs can be used, via suitable interface circuitry, to switch electrical devices, such as lights, motors, pumps etc., in time with the music. Use the outputs to control  tape decks, or energize and synchronize auxiliary circuitry. This provides a direct interface to the world of analog electronics. 

MIDI Specification: 

The outputs are switched ON via MIDI 'Note-On' commands and OFF by MIDI 'Note-off' commands. These MIDI commands are all channel (1-16) dependent. Also, all outputs will switch off if the 'All Notes-Off' command is received. This MIDI command is channel independent.