Over Labor Day, I got this PIC-based addressable matrix scanner circuit breadboarded, coded, and connected to HW1 via MIDI. The program sweeps the full pedal and great ranges continuously with note on / note off messages, and the loose wire on the right could be connected to various matrix pins to drive the first 8 notes on the swell. HW1 made quite the cacophony, but MIDI-OX confirmed the MIDI traffic was all correct.
Here’s the CPU board, running a PIC microcontroller at 40 MHz. J3 is a simple address/data bus that will connect to various other board types.
Here’s the addressable matrix scanner. Moving the jumper on J3 sets the board address, allowing for multiple instances of different types of I/O boards. This one is an 8×16 input matrix that can scan 128 inputs. I may revert to an 8×8 matrix if I have to fit TTL-CMOS level shifters on the boards.
Ambassador Organ 