A Sound Card + MIDI interface for Raspberry Pi computer

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Since Pure Data runs on Raspberry Pi, there was an absence of hardware which enables this pocket computer to be used as a professional standalone device. Now there is pisound.

pisound is the high-quality sound card with MIDI interface for Raspberry Pi (RPi) computers. This card has all what it takes to be considered high-fidelity audio device: legendary Burr-Brown Op-Amps, ADC and DAC, separate grounds for analog and digital signals, low-noise power supplies, metalized polypropylene capacitors at the input, etc. Also it has a MIDI interface. Every hacker knows that UART protocol is the physical layer of a MIDI interface. Since there is no hardware controlled UART pins available on the header of the RPi 3 (just a slow bit-banging UART), we made pisound to work without it (we used SPI) and it's now compatible with both RPi 2 and RPi 3. We also placed on-board pots for easy gain and volume control, an LED for indicating audio input clipping and two LEDs for MIDI in/out transfer indication.

The sound card can work with three sample rates: 48, 96 and 192 kHz. Audio and MIDI drivers are written and can be easily installed on Raspbian OS. And for additional bonus we added a small button which is programmed to find and load a Pure Data patch from your flash drive and to safely shutdown the system if the button is held down for a couple of seconds. The scripts can be edited in order to reprogram the button to do whatever you want.

More technical parameters can be viewed on our homepage at

  • Eternal Testing Is Over - pisound Is Live on Indiegogo

    stuzer03/14/2017 at 16:42 0 comments

    pisound has gone over 6 hardware revisions and it was fun. In the first revisions we had spent hours debugging some noise in ADC and then found that the voltage reference was not connected to the ground. Spent two week on this. But the hardest part was the last revisions where we had to make everything perfect. The result was rewarding: we ourselves started to explore the possibilities of this device. We ran a beta-testing program and the testers were excited. So time has come and this is no coincidence that we had launched our crowd funding campaign on March the 14th. Happy pi-day, guys. You can check us on Indiegogo.

  • pisound with a new power supply section

    stuzer12/26/2016 at 17:27 0 comments

    We prototyped and tested a new revision of a pisound. The major change was made in power supply section. Now pisound is powered over Raspberry Pi and a default 5.1 V micro-USB adapter works like a charm. No more 9V adapter with a coax plug. See the nice time-lapse video of assembling the prototypes for testing.

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AVR wrote 12/24/2016 at 07:46 point

Awesome project!!!! I sort of wanted to make something like this but now I want yours! This will be terrific for running PureData patches on Raspberry Pi 3s.

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Dean Murray wrote 10/21/2016 at 10:17 point

Hi there. Looks very interesting! What can it achieve for minimum number of output sample buffers at 48khz for reliable glitch free sample playback? 

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stuzer wrote 12/26/2016 at 17:11 point

Hi! Thanks! It does depend on the software  run on Raspberry. But with raspbian and PD-test-patch it was 64 frames set as a buffer and 4ms of delay between input and output at 48kHz. It was glitch free. In order to minimize delay and buffers even more, one should go with real-time kernel.

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AVR wrote 02/21/2017 at 20:08 point

was this test conducted with an RPi 3 or an earlier model ? From what I've heard the Pi3 nails PD stuff, which is why I am very interested in buying this board from you. 

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stuzer wrote 02/21/2017 at 22:35 point

Hi, Adam! As I recall, we tested that on RPi 2. With the RPi 3 the results should
be similar. We also got like 2ms loop-back delay with 128 frames @
192kHz, so if the minimum latency is required and the patch is not too
heavy, the RPi 3 and high sample rate could be the way even without
tweeking the kernel:) Thank you for your interest! Now we had tested the
last (7th!) revision and it will be available to order it very soon.

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