Thrilled! Got i2c working through Lemur on iPad and intellijel case

Thanks to the great folks here, I got the i2c thing working with receiving MIDI from my iPad running lemur. But the thing I’m so excited about is that I just got the intellijel case that has the MIDI i/o on the back. I fit the i2c converter directly to that board so I can just use the midi input on the back of the case for the 301. Plus, the case has a couple of 2 pin 5V supplies so you don’t need to waste a whole module slot to power the converter. Yea!


Would love a rundown of this. Have 301, ipad and said case. :slight_smile:


It’s pretty straightforward. If you pull out the midi board on the case, you can trace where pin 4 and 5 of the MIDI in go. I then just cobbled together the circuit combining this schematic:
Note: I used a 6n138 and I just omitted the MIDI out portion. I also put a 10K resistor from pin 7 of the 6n138 to ground to help with the slew rate. THere are a bunch of threads online that talk about that. I’m not sure if it’s needed for this circuit, but I just put it in anyway.

Then I used @anon17137829 great work here to do the schematic from the teensy to the 301:

His code worked well right out of the gate, but I modified it for my needs (got rid of the USB MIDI mainly) and got rid of a lot of the MIDI messages that I don’t plan to use.

For the Lemur end of things, I just go out of the ipad in to an iConnect thing that routes the incoming midi from the ipad out of one of the DIN ports to put in to the case…and voila!

Probably the most difficult part was having to keep remembering what the pinout on the 301 is (I have the rev 7 board) and that there not a good way to keep those connections locked on to the 301. I haven’t tried to pull the CPU to see if I want to deal with soldering the wires on directly.


This might be a good place to ask. Do you know how to get 5V’s out of the USB type B jack on the back of the intellijel case? trying to power a diy’d LED light…

That’s just a plug for future expansion-it doesn’t have any active circuitry connected to it. They have the little usb 1U thing-It actually looks pretty convenient and is on $15:

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ahh yeah i’m familiar with their usb 1u module. unfortunately i have zero 1u space left and thought i could power something from the unused midi jacks on the back. i guess i’ll test the midi out and see if it produces 5v.

Nothing on that board is powered. They are just connectors that are ready to be used. So in that case, I could see you taking the 5V off of the power supply and then hook that in via the ribbon connector to the board. Heck, you might be able to just trace the usb connector there and then route the 5v to the correct pin and use the USB that way.


thanks i’ll do some investigating…also curious about this mod you did for the 301. sounds pretty amazing. I also have that setup and would like to implement that in my case. Do you have any photos from inside the case?

I don’t If I take out the modules I’ll try and remember to take a pic. Not much to see down there. The mod is documented here:

Oh great newz !
And if I connect the midî 2 i2c with a 16n and teletype on a tt i2c busboard all work fine?
And if i just connect the midi 2 i2c on tt busboard do i need the 4.7k Ohm resistors?

Sorry, I don’t know anything about the 16n or teletype. I did this because I don’t have either of those.