1 / 10

Making a MIDI Keyboard

Making a MIDI Keyboard. Bob Wayne Bell, Jr. Nov. 15, 2002 EE281. Introduction to MIDI. MIDI is the acronym for Musical Instrument Digital Interface.

fayre
Download Presentation

Making a MIDI Keyboard

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Making a MIDI Keyboard Bob Wayne Bell, Jr. Nov. 15, 2002 EE281

  2. Introduction to MIDI • MIDI is the acronym for Musical Instrument Digital Interface. • The MIDI protocol allows electronic devices (usually synthesizers, but also computers, light show controllers, VCR’s, multi-track recorders, etc.) to interact and work in synchronization with other MIDI compatible devices. • Using a master controller device such as a keyboard, one can play or trigger sounds from other electronic devices remotely.

  3. MIDI keyboard connects to computer sound card or synthesizer module to create MIDI code. This Project is built around the 8031 microcontroller. Once keyboard circuit diagram is drawn out, one can construct scanning circuitry that continuously loops through a test of each key to see if it is open or closed. Introduction to Project

  4. The Bare Keyboard • One must acquire a bare musical keyboard • Each key (on recent keyboards) will have at least two switches for velocity sensitivity. • Essential to map out the circuitry built into the keyboard because the MIDI interface must be built around this.

  5. Circuit Design • Microcontroller • Memory • Keyboard/switch interface • MIDI/RS232 interface • Power supply

  6. Circuit Schematic

  7. Software Algorithm • The software loops through a check of each 1st switch for every key. • If it finds that switch 1 is open it checks to see if it was open the last time it looked. If this is the case it continues scanning. • If it finds that it is open but was closed the last time it looked then it stores info that it is now open and then sends the "note off value" for that key out the midi port.

  8. Software Algorithm Cont’d • If it finds that switch 1 is closed then it checks to see if switch 2 for that key is open. • If it is open then it increments the velocity register value and continues the scan. If it finds that switch 2 is closed then it checks a register to see if that note is already on. If so then it continues the scan. • If not then it sends the "note on value for that key out the midi port and also sends a velocity value from the velocity table that is incremented for each keycheck loop. Therefore, the more times that the software loops the lower the velocity value sent.

  9. Keyboard to Sound Cable

  10. More references • General MIDI information http://www.midi.com/ • Making a MIDI keyboard http://home.insightbb.com/~tomatwell/midi/midi_key_intro.html

More Related