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:

• 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)

• 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 9 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

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.