Simple active sensing filter

[Dnigrin]

I'm new to Midibox. I would like to build a simple, self contained box that will filter out active sensing MIDI info, and pass everything else. Ideally, I would like this box to not require power. Is this possible with Midibox? It seems that the core32 is overkill for what I want to do. I'm also unclear if I would have to power it via USB or something.

Thanks for any tips or ideas.

[Altitude]

Sounds like a job for the good ol midifilter! http://ucapps.de/midifilter_16f.html. You can run this on batteries but the pic16 will probably be too much for bus power (but dont quote me on that!)

Edited August 13, 2010 by Altitude

[Dnigrin]

Hi Altitude - nice to see you here too!

That *is* quite close to what I'm looking for. Programming in assembly is something I could do without, but it looks like I may be able to squeak by with the examples given. But the bus power is what I'm after, ideally. Anyone know if that's possible? Also - since you are dealing with a total midibox newb here - do I have to get the core PCB board and all of its components as well, or can I just get the PIC and connect power and my MIDI connector I/O to a few of its pins to do the job?

[nILS]

You can easily run a core module off USB power. If there's not purrty LEDs or LCDs the MIDIbox pulls next to no current. You don't need a full core module for that - most of the board is just headers anyway. This shows the mininum requirements for a the midi filter. If you don't feel like writing asm, you can always replace the PIC with one that supports MIOS (18F452, 18F4685, ..) and write the app in C using the MIOS skeleton. Then it's really just a matter of ~20 lines of code.

[Dnigrin]

Thanks Nils, exactly the info I needed! Last question - if I *do* decide to go the battery route, since I'm also pretty clueless with electronics (though I can build things from a circuit diagram quite well), can someone point me to the circuit I would need to build to convert a 9v battery output to the required +5V?

[nILS]

You can simply lift the PSU part of the core module (schem on ucapps.de). You can leave out the bypass caps, if you want to, as a battery is pretty much as stable as it gets: 9V - 7805 - 5V

[Dnigrin]

Thanks again Nils!