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Circuit Description

The circuit shown here implements a MIDI controller built around the PIC16C84. It demonstrates software RS-232 and MIDI transmission, as well as multiplixed keypad and display control. The original name for the design is MIDI footswitch controller, because such controllers are commonly used to switch MIDI synthesizers via foot switches - keeping your hands free for playing your instrument.

The controller periodically reads out the keypad and generates MIDI channel select messages. The MIDI output channel in the demo is fixed at channel 0. However, you can edit the source code and re-run the PIC assembler to select any other MIDI output channel.

When you run the demo, it might be different to read the multiplexed display, simpley because the redraw rate might be too low. However, on fast computers (Athlon, Pentium-IV), the redrawing is often fast enough to read out the multiplexed display in the simulation. Otherwise, open the Java console to see the generated MIDI messages. One of the following applets will demonstrate a different simulation model for the displays, which are much better suited to visualize multiplexed displays.