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Midi signal via serial seems wrong #4

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JonahPi opened this issue Mar 24, 2018 · 9 comments
Closed

Midi signal via serial seems wrong #4

JonahPi opened this issue Mar 24, 2018 · 9 comments

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@JonahPi
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JonahPi commented Mar 24, 2018

I used the Midi package with a very simple program but was not able to get out any tone. Using a similar Python code worked perfectly fine. In both cases I transmit the Midi-code via Pin 0 and use the Midi via Serial command. When I compared the signals from the Phython code with the one from the PXT-code there was an obivious difference. (s.a. forum entry here: link )
@Gadgetoid
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I've just realised this when testing today- it's not actually sending MIDI over Serial at all, but is instead sending a string representation of it.

See: https://github.com/Microsoft/pxt-midi/blob/fb9de98860c6c5cd0a60844673f450f1bc55abbf/midi.ts#L80-L95

The practical upshot of this is that the "MIDI" is very human-readable, but unfortunately isn't readable by any off-the-shell Serial->MIDI bridge software I've come across.

The format is:

midi:<command>,<arg>,<arg> \r\n

(Not I've taken liberty with the amount of whitespace, but that is part of the output)

You could write your own client in Python that handles MIDI messages in this format and injects them directly into the system. It'd be relatively easy using serial.readline.

However I think this library needs a new block: "useRawSerial()"

This block would run the following code:

function send(data: Buffer): void {
    serial.writeBuffer(data)
}
midi.setTransport(send);

This writes the raw - not human readable - MIDI data directly out to the serial port, and I can confirm this works with Hairless MIDI <-> Serial Bridge.

@Gadgetoid Gadgetoid mentioned this issue May 2, 2018
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Gadgetoid added a commit to Gadgetoid/pxt-midi that referenced this issue May 2, 2018
@Gadgetoid
New useRawSerial feature to fix microsoft#3 and microsoft#4
9e6f0e4
pelikhan pushed a commit that referenced this issue May 2, 2018
@Gadgetoid @pelikhan
New useRawSerial feature to fix #3 and #4 (#5)
38674a5
@JonahPi
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JonahPi commented May 20, 2018

Using the new block "midi use raw serial" it works like a charm. Thanks a lot for your help!

@JonahPi JonahPi closed this as completed May 20, 2018
@pelikhan
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Anyone up to write a project on how to use this?

@JonahPi
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JonahPi commented May 20, 2018

micromidiconnection
microbitsamplecode

This setup allows to connect any kind of instrument with a midi-input. I tested it with an e-piano and this little devices which was described in the German Make magazine.

@CaptainCredible
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CaptainCredible commented May 20, 2018 via email

@pelikhan
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pelikhan commented May 21, 2018 via email

@JonahPi
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JonahPi commented May 21, 2018

@pelikhan : Sure, 'would be cool to see more people using it.

@CaptainCredible : No long time tests run yet but I will work on a midi project soon, 'hope it works out.

@pelikhan
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pelikhan commented May 21, 2018 via email

@JonahPi
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JonahPi commented May 27, 2018 •
edited

In this case I think it should be a little bit extended to see the differences between polymorphic and single tones:

let Guitar: midi.MidiController = null
input.onButtonPressed(Button.A, () => {
    basic.showIcon(IconNames.EigthNote)
    Guitar.note(midi.frequencyToKey(262), music.beat(BeatFraction.Whole))
    basic.pause(100)
    Guitar.note(midi.frequencyToKey(330), music.beat(BeatFraction.Whole))
    basic.pause(200)
    Guitar.note(midi.frequencyToKey(440), music.beat(BeatFraction.Whole))
    basic.pause(300)
    basic.showIcon(IconNames.Yes)
})
input.onButtonPressed(Button.B, () => {
    basic.showIcon(IconNames.Heart)
    Guitar.noteOn(midi.frequencyToKey(262))
    Guitar.noteOn(midi.frequencyToKey(330))
    Guitar.noteOn(midi.frequencyToKey(440))
    basic.pause(800)
    Guitar.noteOff(midi.frequencyToKey(262))
    basic.pause(500)
    Guitar.noteOff(midi.frequencyToKey(330))
    basic.pause(500)
    Guitar.noteOff(midi.frequencyToKey(440))
    basic.showIcon(IconNames.Yes)
})
serial.redirect(
SerialPin.P0,
SerialPin.P1,
BaudRate.BaudRate31250
)
midi.useRawSerial()
basic.showIcon(IconNames.Yes)
Guitar = midi.channel(1)
Guitar.setInstrument(MidiInstrument.AcousticGuitarNylon)

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4 participants
@Gadgetoid @pelikhan @JonahPi @CaptainCredible