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USB->MIDI interface — Parallax Forums

USB->MIDI interface

WurlitzerWurlitzer Posts: 237
edited 2008-12-29 14:48 in Propeller 1
Has anyone written an object to use the Prop's USB hardware on the Proto board to directly send MIDI messages to a PC running Cakewalk or other similar MIDI program?

I have completed my organ console program (for the most part) and the new PC to be used does not have the 5 pin din input/output interface. I can purchase a standalone converter but as there are still a couple of free cogs on the prop it might make sense to do it in software.

Thanks
Craig

Comments

  • StefanL38StefanL38 Posts: 2,292
    edited 2008-12-29 14:03
    hello Wurlitzer,

    there are already some threads about connecting a USB-keyboard. As far as I understood the comments

    1.) It seems to be a big challenge to write an USB-stack for the propeller.
    2.) The USB-Hardware is a USB-to-serial-interface. It's not possible to use this USB-connector in an other way than as a RS232-interfaceadapter

    One solution might be to send the MIDI-commands to the PC to a c++ or delphi-program that is able to send Windows-Messages to the MIDI-software

    best regards

    Stefan
  • WurlitzerWurlitzer Posts: 237
    edited 2008-12-29 14:24
    Based on my searches on the forum I believe you are right Stephan.

    My program has 2 MIDI outputs one which would be limited to the standard MIDI speed of 31,250 but the other could be a higher baud rate. If nothing has been written I may just use the external converter hardware.

    Thanks,

    Craig
  • BradCBradC Posts: 2,601
    edited 2008-12-29 14:48
    Ok. The propeller USB is only capable of low speed. USB->Midi converters utilise bulk endpoints and therefore can't use low-speed USB. Now, having said that its certainly possible as both MacOS and Windows allow you to completely violate the USB standards with no complaint, and there is at least one documented case of a USB-> Midi interface on Windows using low speed bulk endpoints.

    So yes, it's possible. It's something I have planned to implement in the USB stack for a while, but never quite got around to. The USB code is here in the forum somewhere. It would not be incredibly difficult to implement a class compliant USB Midi interface on top of the low level MAC code already written.

    You would need at least 2 spare cogs and 3 port pins and about 3-4k of spare hub ram to make it work.

    <edit>
    Oh, I just re-read what you originally wrote. Forget about using the on-board FTDI for anything other than usb-serial.
    Sorry.. I should have read a little closer

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