I received my two MIDI Shield circuit boards from Batch PCB over the weekend.  I’m happy to report that they came out 100% error free.  However, I think I’m going to make one or two minor tweaks before getting a bunch produced.

MIDI requires the use of the Arduino serial port pins, which are also used by the on-board USB programmer.  With my current design the MIDI Shield has to be unplugged before the Arduino can be programmed, which is a pain in the ass.  Instead, I’m going to add a jumper to the MIDI Shield.  Remove the jumper, program the Arduino, then put the jumper back on.  Much better than pulling the whole shield off every time you need to upload code.

The other changes I need to make are to the silk screen.  I forgot to label the positive leads of the LEDs and some of the other lettering is a bit wonky.  All easy fixes that won’t require an additional prototype to be made.

I also need to create a few examples to get people started coding with this thing.  I spent about half an hour coding up a MIDI theremin, but it’s definitely a little rough around the edges.  It works, but I think I need to limit the note range to one or two octaves instead of all 128 MIDI notes.  I might also try to create a dead-simple 16 step sequencer.  With only two buttons and two knobs, it’s going to be pretty primative, but it’ll show people what kind of things the Arduino (and MIDI) can do.  If I come up with anything cool I’ll post a youTube video.

I decided to do a slightly more advanced version of my MIDI Shield this weekend.  It has MIDI in and out just like my prototype, but also has two LEDs, two buttons, two potentiometers, and a photocell.  All the additional components are optional, so if I just need a simple MIDI interface for a particular project I won’t have to bother with soldering on the extra stuff.

I finished up the PCB design today, but I had to make the board double sided, so I can’t make a prototype at home.  It’ll probably take two or three weeks to get my new prototype back from BatchPCB, but I’ll post some more info once it arrives.  Hopefully I have all the bugs worked out and I won’t need to do any additional revisions.

If my full version generates enough interest I’ll probably sell the boards, or even produce a small run of kits.  I’ll also release the board files and schematics under the creative commons license once I know I have all the kinks worked out.

Here’s a sneak peek of what the layout will look like:

I picked up an Arduino microcontroller and a few shields from Lady Ada last week.  I use PIC microcontrollers quite a bit, but I’ve been wanting to switch over to the Atmel AVR because it has better support for C programming.  The Arduino is AVR-based and their IDE uses C so it looked like a good place to start.

One of the things that makes the Arduino so cool are the “shields” you can buy.  They stick on top of the Arduino and let you add additional functionality without the need to breadboard or worry about which wire goes to which pin.  I’ve seen shields for motor controllers, wave playback, LCD screens, ethernet…just about anything you can imagine.  However, I was surprised that no one had come out with a MIDI shield.  I had seen a few posts on the Arduino forums about people breadboarding MIDI interfaces, but no one had bothered making a shield.  My main use for microcontrollers is for music projects, so I decided to make my own.

MIDI I/O isn’t too terribly hard, so it only took me an evening to draw up the schematic, design a circuit board, and etch a prototype.  I made a few minor mistakes, hence the green jumper wires in the photos below.  Still, not bad for an evening of screwing around with Eagle and playing with volatile chemicals.  In fact, it was easy enough that I might just get real boards manufactured and flesh this out into a complete kit to sell on the site.  I can’t be the only person out there who wants to play around with MIDI on the Arduino.  Maybe I’ll add a few knobs, a light sensor and a button or two to version 2.0.  That way people could have a few more options for manipulating MIDI data.