Littlepiggytracker Midi Interface Upgrade


This is seriously awesome. Seriously.

Now, I just need to get my thumb out of my a** (as we say in sweden) and Build This Thing, and after that I'll be making weird, weird portable music...
 
Couple of queries..

Can't the gp2x do the Midi baud rate directly?? (31250bps?)

And shouldn't there be some opto-issolation?

I'm just going off the old interface I built for the Amiga many years ago.

Be quite cool to use the gp2x as a mini sequencer though - especially if you could use the second core for a virtual analogue synth :)
 
deluded said:
Can't the gp2x do the Midi baud rate directly?? (31250bps?)

Be quite cool to use the gp2x as a mini sequencer though - especially if you could use the second core for a virtual analogue synth :)
Click to expand...
The GP2x headers don't support MIDI baud rate directly, that's why the interface needs to implement a sample rate convertor. If you want MIDI plus audio sequencing on the 2x, lgpt is for you :)
 
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deluded said:
And shouldn't there be some opto-issolation?
Click to expand...
Actually this is only usual with Midi-In. We deal only with Midi-Out here at the moment. In the future I will upgrade the Interface also for Midi in and then i will include isolators of course.
 
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Ah sorry - didn't realise it was one way only.

Still seems crazy that you need a PIC to translate baud rates rather than just setting the uart to a non-standard rate via some lowlevel hack.
 
deluded said:
Ah sorry - didn't realise it was one way only.

Still seems crazy that you need a PIC to translate baud rates rather than just setting the uart to a non-standard rate via some lowlevel hack.
Click to expand...
Yes true, but this was actually a fast workaround. If someone can hack the Midi-Baudrate into the GP2x Firmware, that would be alot better of course!
 
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Can you not just write to the UART registers directly, or does the firmware prevent that?
 
Now someone help me: How does lgpt handle MIDI? My weaned-on-ordinary-synths-brain would want a setting on the instruments page, where you could toggle between "MIDI" and "INTERNAL" (and possibly "BOTH"), and when set to MIDI, there would be settings for MIDI channel, default velocity and so on instead of the sample parameters. I can't seem to find anything like that, though...Neither in lgpt nor in the docs. (But the wiki talks about "MIDI instruments" somewhere, so...)

This should possibly be in its own thread. Oh well.

1 brownie point to whoever guesses what synth I first did sequencing from, based on the above text :)
 
deluded said:
Can you not just write to the UART registers directly, or does the firmware prevent that?
Click to expand...
i'm curious about this too. the timing needs to come from somewhere, right? since the bus doesn't provide it. if your program depended on the cpu for timing, you might end up fighting the firmware for it. maybe that's not an issue though, since the cpu is so much faster, and you get to be 1% off.

or maybe, like you said, the os somehow prevents access to the uart?.


semi-related: i know part of the issue with midishare is that the usb handling...but i think midishare can also go over a network connection...maybe that could be implemented without needing more usb control then we already have?

http://www.cs.berkeley.edu/~lazzaro/sa/sfm...x.html#download

not really sure what's involved though.
 
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Moxie said:
I can't seem to find anything like that, though...Neither in lgpt nor in the docs. (But the wiki talks about "MIDI instruments" somewhere, so...)
Click to expand...
Ah - I found some half-spoken hints in the changelog. I'll go check.
 
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Eh. I'm not sure it is even solvable, and besides I wrote it wrong. LOCAL, MIDI or BOTH is more like it. Dementia is setting in.

It has an excellent display that allows me to check and adjust for instance the midi status of all eight sequencer tracks at once :)

You're doing luvverle work on that rhodes, by the way :)
 
Moxie said:
Now someone help me: How does lgpt handle MIDI? My weaned-on-ordinary-synths-brain would want a setting on the instruments page, where you could toggle between "MIDI" and "INTERNAL" (and possibly "BOTH"), and when set to MIDI, there would be settings for MIDI channel, default velocity and so on instead of the sample parameters. I can't seem to find anything like that, though...Neither in lgpt nor in the docs. (But the wiki talks about "MIDI instruments" somewhere, so...)

This should possibly be in its own thread. Oh well.

1 brownie point to whoever guesses what synth I first did sequencing from, based on the above text :)
Click to expand...
Instrument 80 = Midi Channel 1
Instrument 81 = Midi Channel 2
etc.....

And effects can be switched to MDCC or so which stands for Midi-CC
 
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Moxie said:
Now someone help me: How does lgpt handle MIDI? My weaned-on-ordinary-synths-brain would want a setting on the instruments page, where you could toggle between "MIDI" and "INTERNAL" (and possibly "BOTH"),
Click to expand...

Ive been saying this for months. :) I think every instrument should generation midi if set to ON that way your DAW can record midi written on the run.

EDIT: firestarter is faster than I!

2ND edit: piggy only sends max velocity. But you can use a table to set midi volume as a workaround, unless your synth is too cool for that.
 
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In the future I will upgrade the Interface also for Midi in and then i will include isolators of course.
[/quote]

Wow, firestarter! Between this and the P64 midi interface, you've been very busy lately! (can't wait to see someone use the two of them together for the first time)

What will Piggy allow you to do with MIDI in? Would it be possible to record sequences in real time, or to tweak existing sequences? I'm not familiar with trackers, i prefer hardware sequencers, but i'd love to incorporate my GP2X into my midi setup.
 
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to all pondering if the gp2x HARDWARE supports MIDI baud rate: yes it does :)

however, as many have said ... it is the firmware which prevents the gp2x from sending the proper baud rate for midi. this is a legacy "feature" of linux which was built for PC computers with shitty serial ports that had fixed baud rates.

i've talked to craigix about this problem and he's supposedly mentioned it to gph, but we haven't seen a firmware fixed for midi-sending yet. open2x may support this in the future. however, firestARTer saves the day ... today!

firestARTer's solution is a good one that is cheep to build using common parts but anyone could built a baud rate converter. i have a 2uart solution sitting on my desk, the only advantage there was that it made programming the buffer a bit easier.

kingconga: trackers have never been very good at recording notes from midi ... so not sure what marc is planning to use midi in for on piggy. also, not QUITE a p64 synced with LGPT, but here's two tracks of piggy synced with a x0xb0x :)

060124enslavedRuff.mp3
060112brawnDawn.mp3
 
firestARTer said:
...We deal only with Midi-Out here at the moment. In the future I will upgrade the Interface also for Midi in and then i will include isolators of course.
Click to expand...
Great news and project!
A MIDI In could be great too, using Lgpt Gp2X as a small sampler with all the 'piggy tweaks' :).
 
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