It was such an easy thing..


Electronics are like Legos. Buy the chunks, hook ‘em together add smattering of code and you’re a hero!

Ah, The dream! The design was all about, how can I make this look interesting and still be able to 3D print the parts? I was shooting for an Art Deco, 1940s look.

Well, I needed..

  1. BulletA screen for choosing songs.

  2. BulletHardware to actually play the songs.

  3. BulletSome sort of mass storage to hold the music.

  4. BulletAn amplifier to drive the speakers.

  5. BulletSpeakers. Well..

  6. BulletEarbuds for now.

  7. BulletA processor to run everything.

  8. BulletA 3D designed and printed case.

  9. BulletFigure out how control SD card.

  10. BulletWrite code for the .mp3 player.

I went online shopping and bought most everything at Adafruit. I like their stuff a lot. And they are pretty good at getting you at least up and running. And that’s worth gold! It may not be the best solution, but you can look at what you get and make it better if you need to .

This is my “Development system”. It was originally grown for my Breakout game. But it got taken over by the Doorbell project. I just kept adding bits as they came in.

That’s the Teensy 3.2 I’m holding. (Same as a PDP11 I guess, or was it a VAX?) Got some knobs and buttons on it. MP3 player, OLED screen. And, tailing out the end is a set of earbuds.


Well, hardware is all fun and good. But you still need the code to make it all do what you want, when you want.

All the hardware I bought ran on an SPI bus. I’d messed around with SPI bus stuff a little bit, but not a lot. My understanding of how it all worked was a bit foggy. I’d been lucky and one by one everything magically seemed to work. So far..

The music storage would be on an SD card. Again, I’d not messed about with SD card drives very much. I needed to get to grips with that. I’d also just found out that UNIX was originally written for a processor roughly the size of the Teensy 3.2. How cool! Lets start with a command parser and see if I can make the SD card act like its a UNIX drive. ( I get distracted a lot. By now I’ve given up and just let it happen. )

Writing the command processor where I found..

This stuff just doesn’t work right.. >>

One of my daughters lives in a college house with a  bunch of students. The address has the number “5050” in it. This gave them the idea. “Could you build us a doorbell that played The Hawaii 50 these song?” And of course, being ignorant, I was all “Sure not a problem!” And my unimaginable nightmare begin..