GP2X Gp2x And Midi


M-.-n

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Joined
May 28, 2005
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160
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Brussels, Belgium
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discodirt.10pm.org
Hi guys..

this week end I've done an attempt at stuffing midi in the GP2x of littleGPtracker through serial. Apart from the bugging thing that the serial is used to route stdout & stderr, I've discovered the kernel does not seem to support Midi Baud rate. I've got a few options to work around that being mainly:

+ Use a HW baudrate converter. The piggy would spit at 38400 and a little HW device with a buffer would do the baud rate conversion. Fire reckon it is doable without external power and it would make the perfect solution since it needs no kernel mod. It would require a little solder job but no biggie.

+ Ask the open2x team to add midi serial baud support. This would make the cable really easy to do but would require flashing the firmware of the unit to achieve it. Apparently the open2x team is really close to get the firmware out and it should be compatible with FW2.0 with quite a lot of bonus features.

+ Add support for MIDIshare. torpor is doing midishare2x and it is a midi platform that would allow the piggy to use and USB MIDI device compatible with the FW. U could connect a Midisport 2x2 to the GP2x and spit through it.

I'm certainly going to implement MIDIshare and at least one of the serial option but I'd like if anyone had an idea to bring a regular FW2.0 unit to spit serial data at regular midi rate....

Any takers for a solution ?
 

torpor

hack hack hack, the little machines fight back
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Oct 21, 2005
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vienna, austria
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Like I've said before, I really discourage the use of the Serial port for peripherals .. as its the system console port it should pretty much stay the system console port.

The point being, if you can get EXT->SERIAL going, you can get EXT->USBHost going just as easily, and focusing on USB peripheral support instead of hacking around with the console i/o is a 'safer' bet for future peripheral use on the GP2X. Keep in mind that its *very* simple to make an EXT->USB cable (having done it 4 times myself) and having USB Host properly working on the GP2X should be a reality for a majority of the users soon enough .. either GPH is going to make cables, or someone else will, or we'll see the release of the non-developer BoB that just makes this all a moot issue.

When that all happens, serial console should just *stay* serial console .. it is useful for debugging, it is useful for users to see whats going on with their system, it is generally another 'interface' to the GP2X system, which you'd be interfering with 'non-standardly' if you were to try to make it a peripheral interface. I'm not saying you can't do it easily enough - write a script to hack /etc/inittab and kill initd - but I am saying that the safer peripheral route is all USB, baby, and nothin' but ..

Apropos MidiShare GP2X: it is running, it is stable, and it works very well .. the only issue I have with releasing it for developers right now are related to the OPEN2X project, and solving the gcc2.95.3 vs. gcc4.0.1 vs. kernel-2.4.25 vs. soft-/hard-float issues .. DJWillis and I have been working on this, and the plan is to get a factory-compatible, completely source-built, OPEN2X firmware out there and actively available for use by those who want to run it .. with this first step done in the OPEN2X world, it will be a *lot* easier, and more attractive, for developers to start using MidiShareGP2X to turn the GP2X into a powerful music workstation ..

Since MidiShare comes with a high degree of kernel integration (for performance reasons) it is fairly important that there is a parity between the MidiShareGP2X port and the OPEN2X effort. GPH FW2.0 currently will not support it; the future, new, fresh release of an OPEN2X FW, however, will rock it ..
 

herr_prof

Still Fresh
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Aug 22, 2006
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New York City Ish
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www.toilville.com
Its kinda of a drag to have to buy a commerical midi interface plus the cable for a "portable midi solution". Is there a chance of getting simple midi out in one homebrewed cable? One GP One Cable and One Synth is very attractive...


Peter
 
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