2019-04-29 (M) Electronic Wind Chimes EWC

One of the ideas for this build made some of the precious controller pins reserved so they could potentially be connected to an external device for triggering notes. While keeping these pins from doing something useful, the serial input port was being ignored. Once it became apparent the IO pins were too valuable, the compromise was that input would have to come over MIDI, which would mean accommodating an incoming MIDI signal, which had not been done by me before.
MIDI in and MIDI out ports

An image search for "MIDI input schematic" will turn up a variety of circuits and most of them will work. Many of them feature an optocoupler, a part that was in stock. In front of the optocoupler was an ordinary diode, but an LED was more convenient. This circuit was assembled in temporary dead-bug fashion to test it.
An attempt at an optocoupled circuit

The circuit failed, but the LED would light up when the leads were reversed, so power was getting where it was supposed to be, but nothing was reaching the controller.
Receiving signal, loud and clear

Some hunting with a continuity meter revealed that the wiring running to input 19, the serial1 receiving pin, was terminated to an unconnected via. I forgot that this was done on purpose to place the MIDI input circuit on the controller board where it would eventually be bridged to the pin. That is what I get for planning but forgetting.
Unjumpered wire

The rest of the posts for this project have been arranged by date.

First time here?

Completed projects from year 1
Completed projects from year 2
Completed projects from year 3
Completed projects from year 4
Completed projects from year 5
Completed projects from year 6

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