miniMidiOut

A "fast" (booting) usb-midi input to audio output synthesizer with 5 popular waveforms. It supports velocity, pitch bend and sustain.

Specials

• Pi1 and eeepc is NOT a MUST-HAVE
• Mainstream CIP RT kernel (6.1.157) for Pi1 and eeepc
• system runs from RAM, not from SD
• boots up in 15s on Pi1 and 8s on eeepc

It is not realy realtime

Messure delay between key press and audio out (tested with v1.5.4):

• Pi1: 64ms
• eeepc: 48ms

Usage

You can use (and build) the command line interface (CLI) miniMidiOut on many Linux systems. It does not depend on a realtime linux-kernel.

For Pi1 or eeepc use ready to use Release Files:

• use my Pi1 sd-card content (just a single FAT32 partition is needed)
• use my sd-card image for the eeepc 4G 701 (32bit Pentium, BIOS boot)

With these files/images the system boots a minimal Linux and autostarts miniMidiOut.

1. plugin sd-card
2. plugin MIDI USB keyboard
3. if the MIDI USB keyboard has its own power button: power on!
4. optional: plugin an USB alphanumeric keyboard
5. plugin your headphones to the analog audio
   • pi1: If you use the HDMI plug, the audio signal is there. (not recommended!)
   • pi1: Attention! There is a 4th connection for analog video in the 3.5mm hole :-S
6. power on the Pi1 (or eeepc with ESC-key and boot menu)
7. wait until 3 tones comes up
8. enjoy classic synthesizer sounds from the 80th !
9. power off the Pi1 (or eeepc)

Features (alphanumeric keyboard: numpad!)

• press 1 for sinus
• press 2 for saw
• press 3 for square
• press 4 for triangle
• press 5 for noise
• press 0 for sustain (do not use together with sustain pedal)

Change fading out the tone (release):

• press 6 for default
• press 7 for a long fade out
• press 8 for no fade out
• press . toggles
  • automatic fade out on
  • automatic fade out off
  • if release the key, the freqency goes up
  • if release the key, the freqency goes down

Change octave:

• press - to set down
• press + to set up

Change modulation:

• press / to set down (or off)
• press * to set up

Feature (MIDI keyboard)

• velocity
• pitch bend (+/- 4 half tones)
• sustain pedal

Switch through the waveforms saw, square, triangle, noise and sinus:

• no sound should be played
• you press the sustain pedal 3 times in 1.5 seconds

Listen to the Audio File

Bugs

Hotplug does not work.

Details

See this file for more details to build and use miniMidiOut.

Real 8Bit Sound

Check this branch, if you want to skip Linux and 32/64bit or the C# Windows Version and just want to plug your USB-Midi keyboard to an 8 bit Micro controller. But it is rectangle only!