** UPDATE #2 ** Check out latest post & board revision here
** UPDATE: You’ll be able to get these boards soon at tindie.com in the DTronixs store
This is a simple Serial based MIDI breakout board for the Raspberry Pi.
It uses the Raspberry Pi hardware UART RX and TX from its expansion port to provide a “MIDI In” and “MIDI Out” function. The board was designed in DesignSpark PCB and the schematic is here
Zuzebox's Blog 
Wow not only a reboot for computer science also some interesting prospects for music tech
It makes me wonder if there are linux arm drivers for some low noise
usb audio inputs.( porta studio me thinks ).
There should be a resistor from MIDI Out pin 4 to the 3V3/5V rail. This prevents an external cable fault or incorrect cable usage shorting pin 4 to 0V and blowing the supply.
Having missed the 220R resistor off the +5V line on the MIDI out connector that’s shown in the MIDI spec a user could short the +5V line to ground.
Martyn.
Martyn/Jason thanks for the advice. I’ll add a 220R resistor to the circuit and update the files
[…] a semi-related note, [Tony] is building a GPIO MIDI interface for his Pi. Yes, he could just get a USB to MIDI adapter and call it a day, but this is a far more […]
[…] a semi-related note, [Tony] is building a GPIO MIDI interface for his Pi. Yes, he could just get a USB to MIDI adapter and call it a day, but this is a far more […]
[…] a semi-related note, [Tony] is building a GPIO MIDI interface for his Pi. Yes, he could just get a USB to MIDI adapter and call it a day, but this is a far more […]
[…] a semi-related note, [Tony] is building a GPIO MIDI interface for his Pi. Yes, he could just get a USB to MIDI adapter and call it a day, but this is a far more […]
[…] a semi-related note, [Tony] is building a GPIO MIDI interface for his Pi. Yes, he could just get a USB to MIDI adapter and call it a day, but this is a far more […]
Got here because apparently you can get a 20% performance boost on the rpi if you disable the USB driver… which means no input unless it’s through GPIO pins: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=28&t=7866
Thanks for the tip
so have the resistors been added? the pic still shows v0.1, so I guess it’s still not there…
Hi Alex,
Yes, I’ve added the resistors as suggested. I’ve revised the size of the board to be smaller and fit the MiniPiio format (40 x 50mm) as I’ve been using for other designs. I’ll post the new design shortly.
Tony
Will you be selling pcbs at any point?
Hope so soon. I’ve seen the gerbers for the smaller MIDI board (i.e no DIN PCB connectors) to be manufactured. A blank PCB should cost ~ £4
Hey, this looks very good. I’m about to start(when i get my rPi) a project with arduino+rpi+pd. But i’d need two midi inputs. And no output. Is it possible to do?
Getting two MIDI inputs from the RPi expansion port might be a bit tricky as it only has one UART interface. You out use a USB MIDI adapter but if you really want to use the RPi expansion port (which does make a nicer packaged solution) you could use a dual MAX3109 UART-SPI chip from Maxim.
That would seem to miss a trick seeing as how one can chain MIDI devices, no?
True, there is no MIDI pass through but it was my intention to use the RPi as either a control surface or a soft-synth so it so MIDI IN and MIDI out are enough for my needs
[…] […]
Does this make MIDI more reliable on the rPi vs a USB midi interface?
Reliability for the add-on will be as good as any USB interface. There’s less to go wrong 🙂
[…] Building a MIDI interface as mentioned above – picture here and schematic for building it here […]
How do you deal with the non-standard baud rate of 31.25 kbaud? Will the RPi’s UART do that?
The Pi doesn’t support 31.25K baud directly but you can trick it by messing around with the system clock and baud rate registers.
Here’s a cool link explaining how to do it:
http://m0xpd.blogspot.co.uk/2013/01/midi-controller-on-rpi.html
great project. How’s the CPU usage with MIDI traffic? Lower than with a USB interface? This should also help keeping USB free from other things that need it.
I can’t say I notice any difference
Are these going to be made again sometime soon? Do you have the circuit diagram available if I would like to get some made?
I’ve made a few sample boards but getting the Pi to generate the correct baud rate is tricky.
Hi zuzebox,
A litttle late to comment maybe, but I had a question about this setup. Maybe you could point me in the right direction?
How does one setup the configuration for alsa-midi to know what port to use etc, once the hardware is connected. I know you are using the UART rx and tx pins, and I can understand that you need to change the UART clock rate, but I can’t find any info about how to configure it beyond that. I have searched pretty hard to find out myself.
Any pointers appreciated.
Cheers
Shannon.
Hi
It’s an old link but check out m0xpd advice
http://m0xpd.blogspot.co.uk/2013/01/midi-controller-on-rpi.html
Hope this helps. Let me know how you get on.