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MIDI note for key pressed


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UPDATE: This update was made possible due to the kind help of Steve44. According to an online tutorial written by Jim Heckroth, Crystal Semiconductor Corps, published by The MIDI Manufacturers Association, the keyboard sends a Note On message on the MIDI Out port. The status byte indicates the selected channel number, followed by two data bytes: key pressed and velocity. Eureka! That narrows it down considerably, and I at least know I'm barking up the right tree. But I still don't know how to fish the stream for a byte. How does one find the byte in the serial stream? Does it arrive LSB or MSB first? Does the signal need to be inverted for DC circuit logic?

I want to build a portable pipe organ. The bulky keyboard and massive mechanical routing will be replaced by a MIDI keyboard and a single circuit board. The accoustic brass pipe output will be preserved. You won't be able to pick up the pipe cabinet by a handle, and carry it. But I'll gain enough in portability for performances to be possible in venues otherwise impossible.






This message has been edited by Jim on 03-25-2001 at 09:50 AM


This message has been edited by Jim on 03-28-2001 at 01:12 PM

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That sounds like a cool idea. Once you get it to work, you should submit it to the Keyboard of the Month! While I can give you some specifics on Midi stream info now, you'll probably want to check out a more thorough resource like the book Midi for Musicians , or a Midi tutorial which must be available on the web somewhere. If I weren't in the middle of a term paper I might actually go look for you.


When you say "stored in the midi out" I'm not sure I understand what you mean. The midi-out doesn't have any buffer that dictates what any of the information going out the port will be called, it just sends the info from the brain of the midi keyboard. But the midi signal is not generated at the key either, it's generated in the little brain/computer that takes the scanned info of the key contacts and then compares it with the current transposition setting and creates the midi on data.


If I remember correctly, a normal Midi message is three bytes: the first byte is the indicator, it tells what type of information is coming up. The second says specifically which midi control number it is, and the third byte is the value. In the case of a note on, the first byte says that it's a note on, the second says what number the keynote is and the third is the velocity (which you'll probably want to ignore for the pipe organ). As for the exact makeup of the first byte, I remember it being split up into 3 and 5 bits but beyond that I can't remember exactly what it says.


Now that I think of it, Craig Anderton wrote that original Midi book, so you could probably just post this specific question on his board. Good Luck!!

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