Here is the description a 32 outputs MIDI able to switch relays, electromagnetics devices… in order to automate a mechanical musical instrument, or command lights…
MIDI datas from a musical instrument equipped with an MIDI output or from a sound card of a computer are analyzed by the software present on the PIC 16F84. Optocouplor IC10 (1N136) ensures the galvanic insulation.
The outputs of PortB form a 8 bits parallel bus data towards the four 74LS574 (8 Latches),
the outputs of PortA 1,2,3,4 order the memorizing of these 74LS574
Buffers ULN2803 make it possible to control loads until 2 A .
The power supply 5V is articulated around a regulator 7805.
Connector CN7 receives the power supply from 9 to 24v according to the type of relay or electromagnet.