2021-12-10 (F) Weekly Summary

The lunch box I picked for the drum machine was nearly $20USD, so I was nervous about drilling into it. The metal wasn't strong enough to withstand severe screw-ups, but I drilled three holes for MIDI ports and a cluster for the USB power. Once everything was mounted, I was happy with how they turned out.
Data and power ports

Some people say that MIDI inputs MUST have an optoisolator, while some argue that modern microcontrollers can handle data directly from another controller or instrument. I decided to play it safe and include the isolation circuit. Instead of bumbling in with a fully soldered prototype board, like usual, I connected the components on a solderless breadboard and ran wires from my controller. Everything worked!

I made up six copies of the optoisolator circuit on scraps of stripboard. I should have taken a picture of the back of the PCB to show how the copper traces aligned and where I cut two of them. The circuit is easy to find, so I won't worry. I was nervous about using larger-than-necessary boards, but I knew I could trim them later.
MIDI input prototype boards

I connected the three MIDI ports, the incoming USB power, and my LED panel power to the optoisolator board, which was an ideal size for all those wires. By distributing power from the central spot, I minimize the loss to my lights and controller.
MIDI ports, LEDs and incoming power

While connecting my MIDI ports, I kept asking myself if I was doing it backward. One way to tell is to jam an LED into a socket and see where the positive lead works. Instead of relying on that method that could burn up an unprotected LED or make a short to ground, I designed and built a simple tester that will turn on a green light if it's working or a red light if it's backward.
Testing in progress

The final test of my wiring was to put it into action. I wrote a function to display all non-zero serial data on my screen. When the code worked with my timing panel, I added to it to pass all data to one of the output ports. Since there was no musical note data from the timer, I connected a MIDI button array and a General MIDI synthesizer. My notes all passed, but they got delayed when there were many.
MIDI devices in a line

The rest of the summary posts 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
Completed projects from year 7
Completed projects from year 8

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