Raspberry Pi MiniPIIO MIDI board

I design my first Pi MIDI interface way back in 2012 while I was waiting for my first Pi board to arrive.

It’s went through several revisions since then and now looks like this:

RPi_MiniPiio_MIDI_small

RPi_MiniPiio_MIDI_Front_small

The circuit is now completely 5V as per the original MIDI specification but the MIDI IN is 3.3V compatible with the Pi via a voltage divider circuit.

OK that’s the hardware what about the software?

Getting a MIDI 31250 Baud Rate on a Pi is not easy as it should be as 31250 is not a standard Pi baud-rate. But you can trick your Pi into it if you overclock (or rather underclock) the UART clock.

Start a terminal session and type:

sudo nano /boot/config.txt

Add these lines to the end of the file

# Change UART clock to 2441406 for MIDI 31250 baud rate

init_uart_clock=2441406
init_uart_baud=38400

save and exit.

Once saved reboot your Pi.

Next we need to stop the serial UART being used by Raspbian for the shell console. Check my previous post “MiniPIiio RS232 set-up” on how to do this.

Finally we need to add the following to “cmdline.txt”

bcm2708.uart_clock=3000000

After doing all of this we should be ready to connect a MIDI keyboard or synth to our Pi.

 

Again I hope to have it stocked in out our store on Tindie soon:

https://www.tindie.com/stores/DTronixs/

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15 Responses to Raspberry Pi MiniPIIO MIDI board

  1. József Molnár says:

    It’s possible to get/buy the new board’s (schematic) draws?

  2. Phil Ogden says:

    Any progress on getting these in the store?

  3. Mike C says:

    Really interested in getting the board, is it available yet?

  4. […] The first part of this post are some instructions I wrote back in 2014 (more here) […]

  5. John Doe says:

    Hi…
    Is it possible to buy a RPI midi board pre-made/build?

  6. Gareth McComb says:

    I have an idea for a midi project that I would like to get off the ground. Modern arranger keyboards that the facilty of what is called “Single Finger Chords” this allows unskilled players to be able to use “Fake Book” sheet music but instead of having to play all three or four notes that make up a chord you use either one note for a major chord and the processor in the keyboard detects this and adds the other two notes and sends a message to the tone generator and the keyboard then plays all three notes. Now this is very much frowned on by “real players” however it can sound good. I use this technique however I have been asked to play an organ in a church whose organ does not support “Single Finger Chords” and but the organ does have midi in and out. So here is my basic idea. The organ has three manuals (keyboards) if would like when I play for instance a C note that it will be sent out of the midi out port and sent to a Raspberry PI midi in port which looks up a table and says add E and G to make up the rest of the chord and send a message back to the organ via the PI’s midi out port and the organ receives the two messages to play E and G and it continues to do so until the C note is no longer pressed. Other chords could be added based on what note is sent to the PI and the corresponding message sent back to the organ. Possible? Difficult? Comments or questions would be appreciated.

    Many thanks in advance.

    Rgds

    Gareth

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