Included in the Patch-a-Tron hardware is a MIDI implementation that allows the circuit bends in the Patch-A-Tron to be controlled remotely. The hardware interface consists of the standard MIDI DIN connector fed to the Arduino UART through by an opto-isolator, per the MIDI specification. (details at - http://www.midi.org/techspecs/electrispec.php)

The schematic below shows how to connect MIDI hardware to the Arduino. The arduino should be connected via one of its hardware serial ports. [Patch-a-Tron uses port 2 by default on the Mega, pins 16(TX) and 17(RX)]

The software currently only implements the Control Change and Program Change MIDI events with the idea being that the same sequencer could control both the Roland and the Patch-a-Tron and get repeatable - predictable - sequencable circuit bends that go with the sequenced rythm. Control Change allows the user to choose memory banks (A-D). Program Change selects pitch bends to activate. Banks A-C only save 128 bends per bank(0-127). Each 'bend' consists of one 'bus' of of max 48 switches. Bank D saves only 16 slots(0-15). But each slot contains the configuration for all 384 switches.