Arduino MIDI-in shield

This instructable shows how to build a shield to connect devices that send MIDI signals (e.g. a masterkeyboard) to an Arduino.
The basic schematic is derived from: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1187962258/

Step 1 The schematic

Basically the schematic is just an optocoupler with some resistors to decouple the MIDI device from the Arduino.
Note that the DIN connector on the left side is seen from the back (solder pin-side).

Comments

[pluseinn]

If you are having a problem with this schematic then this might help. Don't connect anything to the pin with the 100k resistor on the drawing. This took me a week to figure out.

[gel.]

Would you know where to buy a MIDI connector? I've been having problems finding a source besides SparkFun.

[carkat]

hm - i could recommend some place but don't know if they would be helpful since i'm based in austria/europe. mabe someone else has an idea?

[mortaldoom780]

I made this circuit, debugged it, asked in forums, and it STILL does not work!!! What could be wrong? I am using the 4N28 as above

[carkat]

uh... hard to say from a distance... maybe a few hints:
- is it really the circuit or is something wrong with the arduino (i had that problem, see above) or is the MIDI-signal not coming through properly?
- are there any solder bridges or something that looks strange?
- did you solder the DIN connector to the circuit in  the right way
- try to change the optocoupler, i once had a broken one
... anyone more suggestions?

[mortaldoom780]

Ok I fixed it. It seems that it does not operate with the 100K resistor on pin 6 connected to ground. I removed the resistor, and left pin 6 connected to nnothing, and I am now registering serial data. Now I just have to verify the operation will be reliable...

[daulef]

I'm going to try and use this with the Auduino Synth, maybe use a proto-shield instead of etching my own though..
cheers!

[carkat]

this sounds great! would be cool if you could write an Instructable when you figured it out... i would definitely like to build one! best, carlos

[daulef]

I've got a couple of instructables in the works atm, but the midi auduino is on the cards!

[ReCreate]

Wait..Arduino's can play midi's?

[carkat]

well, at least it can recognise the MIDI signals. what you are doing with the signals then is up to you: assigning frequencies to it and sending it to an amp/speaker (=a simple synth) or driving relays (like i am going to do) are just two of a lot of possibilities :-)

[ReCreate]

Oh i get it now ;)

[dfowler7437]

I recently posted about some Breadboard adapters at uCHobby including a MIDI In and MIDI Out adapters. These could be used the Arduino and feature an enable that allow for safe use along with the boot loader. I will try to have a more detailed write up on the MIDI adapters soon.