usb communicatioons

Posted on 2012-03-17
Last Modified: 2012-03-17
I would like to write a java routine to send and receive from a usb port.  I have been looking at several sites and it appears to more than a trivial task.  I did run into this response to the question on a site and am curious about the statement concerning mounting it and writing to it like a drive.  Anyone have any insite on this approach and maybe a little explanation as to how to do it?

The following is the posting from the other site:

if you are looking to directly build something in low level you can see for information about specs...

If you want some examples of code you can look at ... It's in C though.

If you just want to communicate with the USB in linux, you can just have linux mount it and write to it as a regular drive without having to deal with all the other stuff...
Question by:sargent240
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LVL 83

Accepted Solution

Dave Baldwin earned 500 total points
ID: 37733777
USB is a network interface, not just a port.  Most devices require low level drivers.  Generally speaking, I don't believe java is suited to that.  So for most devices, you need to talk to the driver and not the USB 'port'.  If it 'looks' like a disk drive to Linux, you can address it that way.

Author Comment

ID: 37733782
Your saying it does not look like a disk drive, right?

Author Comment

ID: 37733785
I'm trying to control a music keyboard with a computer and can do it with the rs232 port.  When I plug in the usb to midi cable "midi1" appears in the dev directory.
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Author Comment

ID: 37733802
Can you tell me what value there is in the "midi1" entry in the /dev directory when I plug in the usb to midi cable if any?
LVL 83

Expert Comment

by:Dave Baldwin
ID: 37733816
I suggest you try to send your data to the 'midi1' device like you would a file.  That would be standard practice in Linux.  Open, read, write.  You should get the same responses as from your RS-232 version I would think.  Just a different interface.

Author Closing Comment

ID: 37733864
Again Thanks.

Author Comment

ID: 37733875
I have one other question and I will open a new question if you like, but how is the baud rate controlled if it is handled like a file?
LVL 83

Expert Comment

by:Dave Baldwin
ID: 37733976
Midi only operates at 31.5 kBaud as far as I know.  You don't have to set it for a USB MIDI interface.  This seems to be the best Linux MIDI resource I can find at the moment.  Many older links for this subject are dead.

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