newbie Micro-controller questions

[necrofix]

Ok, heres the thing..

I want to design a kind of midi foot pedal to use with with my Line 6 pod xtpro, I say kind of because being a guitarist and a wheelchair user i cant use foot pedals... which has always been a pain in the... well you get what im talking about  :P

So i want to make a 2 button (up patch, down patch) device, small enough that i can attach to any of my axes. The only thing that is stopping me right now is the use of micro controllers, i just dont get the idea, I see all different kinds of them,

are any kind of PIC usable or do i need a specific one for midi use?

Is there anything to look out for when buying one?

Are they even essential for use with my idea or any midi device?

Just a few questions that im sure someone wouldnt mind answering for me lol.

[audiocommander]

Hi,

you could take a look to the Wiki, there's a floorboard project linked; I think that might be just what you're looking for ;)

Cheers,

Michael

[DavidBanner]

ounds like you need to build a core and possibly a DIN - see the menu on the LHS of the page

that is assuming the POD allows you to control the parameters you want via midi....

[moxi]

hi,

I think you can realize your project just with a core, using j5 as digital input :

http://www.ucapps.de/mios/j5_din_v1_3.zip

http://www.ucapps.de/mios/j5_din.pdf

quote from the main.asm file of the link above:

; The DIN pins are triggering MIDI events in this example.

; By default they are assigned to the Notes C-4, D-4, E-4, F-4, G-4, A-4,

; to the Sustain Pedal controller and to a Program Change Event

; The events can be changed in the MIDI_EVENT_TABLE at the end of this file

now you just have to find some rock solid butons...search for "anti-vandalism" buton, those used on door interphone (hope this things is called like that in your langage ;))

all is already done...

[DavidBanner]

but if you are going to the trouble of building a box it might be worth looking at throwing some extra features in there too....

[necrofix]

Thanx for your replies, i shall check out them links now  :)

Do you have any extras in mind david? im very open to ideas at this stage, im not sure how it will comunicate with the pod (im guessing thats what the PIC does?) btw, salad fingers rules!!

[DavidBanner]

yeah man salad fingers rocks - I've based my whole life around his teachings....

Do you have any extras in mind david?

well, that's the cool part - it's down to you. as you learn while building the core and possibly a DIN, AIN and DOUT you will start to have major brainwaves as to how you can totally change the way you produce/write/perform/play etc...

im not sure how it will comunicate with the pod (im guessing thats what the PIC does?)

The PIC is the brain of the core which is essentially a interface between midi and the various inputs/outputs like buttons, pots, leds etc.

As long as the Pod will accept midi messages to do what you need it to do you are in business.

a quick idea that comes to mind is this:

you have various buttons that are emulating pedals, it would be nice to have an led to show if it's on of off...

also have you checked out some of the plugins that do amp emulation? some of them are amazing, I run a whole lot of my stuff (from vox to drums to synths to pads) through guitar amp vst plugins

[necrofix]

So do different PIC's all do the same thing, its just a case of programing them?, because ive noticed that there are alot for sale on ebay and was thinking of buying a few from there, just not sure which are best.

I do have a few amp sim progs, Amplitube and Amp farm, though i dont use them for guitar anymore after getting the POD and with it having usb on it and being able to get different emulators and effects from line6.com thats all i use now.

As for the *pedal* i want to make, i think the led idea is a good one, i'll have to put pen to paper and draw a couple of ideas out. The way i can see it is, the main box (which will house the core and ins and outs) which will then go to the POD via midi cables, then another cable (say at least 2m long) attached to a smaller box that will have the patch up/down buttons inside it that i can stick to, or inside a guitar.

In theory it sounds easy....

[Screaming_Rabbit]

So do different PIC's all do the same thing, its just a case of programing them?, because ive noticed that there are alot for sale on ebay and was thinking of buying a few from there, just not sure which are best.

... No. - You can't just take any PIC... why would they make different types then?

You have to use the specified PICs discribed on ucapps.de. They're tested or better said, MIOS was programmed for them. The used PIC has to have enough memory, has to understand the code, has to have the right amount of I/O-Pins, the right clock capability and, and, and...

Look at it like this: The PIC is almost like a preconfigured PC, the setup of which you can't change. MIOS is like Windows and doesn't do much if you don't run an application, it's there to handle certain routines and builds the platform on which an application can be ran on. The application like e.g. MidiBox LC is the program like e.g Word for Windows. This is where the logical behaviour is configured like e.g. Button A sends MidimessageXY or incoming MidimessageVW is making LED_B light up.

Greets, Roger

[DavidBanner]

nice explaination there Roger!

It's been like this for me: at first overwhelming when you get into the electronics and code, then after lots of learning and experimentation it all becomes  quite logical and a matter of a bit more learning to fill in the gaps, experimentation and coding to get pretty much anywhere you want within the parameters.

And of course when you get stuck there are amazing people on here to point you in the right direction. I've found as long as you are putting the work in and provide detailed reports on problems, the people who hang round these parts are amazingly helpful and generous with their time.

Building a (custom) midibox and custom app is like taking a crash course in electronics and at the end of it you get a custom controller exactly right for YOUR needs. Someone said to me it was like taking a crash mechanics course and getting a hotrod at the end of it!

As long as you have the time and patience it's a very worthwhile project.

I've been juggling way too many things and using the box project as a sort of focused relaxation in the few bits of time I can get here and there. I still need to finish the first box, but already have about 5 new boxes in my head to fill various needs.

so really long story cut at the long point: if you're into it, jump in, start reading EVERYTHING on the site then the Wiki then the forums. Then once your brain has stopped the swelling and the dizzy feeling has gone away, plan the 1st protoype, order the parts and equipment and fire up the soldering iron, coffee machine and possibly some of Holland's finest....

[necrofix]

Good advice, Thank you.

You are right when you say that all the info is overwhelming, ive been dropping in on the site for a while now and trying to absorb bits here and there, but over the last month or so have had the itch to start building, its just a case of knowing where to start and sometimes i need pointing in the right direction.

I have a basic knowledge of electronics because it was part of my national diploma in music tech, We built things like amps, stomp boxes, noise gates etc, but the closest we got to midi was learning how to wire a 5 pin plug, we never actually got to find out whats inside a synth or interface... which is strange because a good portion of that course was spent using midi. So i wasnt actually sure what the controllers did but roger has made things alot clearer, thanx.

At times the brain does feel like exploding as its all ive been doing lately is purchasing books and refreshing my brain on things i had forgoten, like ohms law, paralel and series resistors etc. But like you said, at the end its like getting a hotrod, and that idea appeals to me very much, that and im getting sick of using the mouse to tweak things... i prefer more hands on, and its another piece of gear for my studio

And i know by hollands finest we aint talking cloggs haha.

[stryd_one]

I say kind of because being a guitarist and a wheelchair user

Slightly OT, but in case you missed this, I thought it was awesome:

courtesy of http://www.otheroom.com/namm/goodies.html

[necrofix]

lol!! that is awesome!

I wouldnt mind one but all my guitars are of a pointy shape so its hard enough trying to find a stand they'll rest in lol

[MRE]

As for the Micro-controller question: If you went with another pic, you'd it be starting from scratch with code. Not that other pics are unable to do what you want, but why work hard, when TK has done that for you? :)

It might make more sense to mount the controller to the chair...or at last make it attachable/detachable. Reason being, all but the most basic of midibox setups take up some space.  Fitting all to the guitar would be very difficult.  (were you still thinking on that line, or am I mistaken?)

Anyway, you COULD mount the switches and LEDs to the guitar and use a metroplexing arangement to get them onto a small cable (ethernet perhaps). Then have the core somewhere else.

[necrofix]

My plan is to make a very simple controller first then move onto the 64. Just a box that houses the core that hooks up to the line 6 (pod), then another cable that will have 2 (maybe more) small buttons that will attatch to the guitar for switching through patches, the core will remain with the guitar rig (amp, POD etc) and the guitar will be hooked up to the core through a few meters of cable (i think thats what you mean by metroplexing, am i correct?), enough room to move freely live and rehersals without being stuck next to a marshall stack cranked at 11... as per usual :P

[DavidBanner]

stuck next to a marshall stack cranked at 11

with an Armadillo in your trousers right? ;)

[necrofix]

Ahh, i was wondering what that was!!

Now all i need is a few midgets to dance around my mini stonehenge... anyone fancy it?  ;D

[cimo]

hi necrofix

i had the insane idea to mount a MidiBox directly into a guitar s body having some knobs and buttons on the lower side of the picksguard ....

simone

[DavidBanner]

Now all i need is a few midgets to dance around my mini stonehenge... anyone fancy it? 

maybe you should have a word with Lady Sovereign....

have you checked out how Line 6 do the controls on their Guitar?

also - how about buttons on one or more of the arm-rests of the chair (i think someone else suggested this too), built so you can hit 'em with your elbow, without having to stop playing?

mmm, could also put 2 big buttons on the inside of the arms so when you shift your weight/lean to one side you can push them (in fact you could probably cable tie/velcro some conventional pedals to do this too)....

[necrofix]

I also thought about building it into the guitar simone, but all my guitars are of different shapes, none being a standard shape like a les paul or strat, so fitting one seemed alot more hassle, plus i would have to build one for every guitar that i use live. i would like to try it one day though.

I think line 6 variax's are controlled with the same foot pedal used to controll the POD... i think.

I like the button/armrest idea, only problem being my chairs dont have any lol, but after reading your post i did sit, staring at the chair for a while, thinking bout drilling some hole in it and threading the cables through the frame and having the buttons someplace on the chair, only problem being is not being able to remove them leaving them open to the elements and being bashed about getting in and out my car or on drunken rampages. I think having a detachable controller at this point is the way to go as it would be easy to hook up to any guitar in no time.

Before i got the POD about a year ago cable ties served me well for quite a few years, i used to tie the pedals to the spokes.

Its good to have people throwing ideas at me, they are all very much appretiated  :)

I have included a pic so you can see where im thinking of attaching the controller

[DavidBanner]

I think line 6 variax's are controlled with the same foot pedal used to controll the POD... i think.

last time I had someone with one of those in the studio I'm sure they were using knobs on the body of the guitar to change the settings, but no pedals were in use as I was doing all the processing via PC...

mmm, no arms eh? Maybe making some special arms that clamp onto the frame easily (using pipe clamps maybe) for gigs and practice?

[stryd_one]

Hmmm... if it's only two buttons... I reckon you could run a good quality shielded wire up to a metre or so, to a very small pod with just the switches, and have the core (no DIN required) somewhere more convenient (like on your belt or tied to the chair's back or something).

I was thinking, a SPDT momentary toggle [eg (ON)-OFF-(ON)] could be mounted in the front panel of all your guitars (just one hole to drill), and a jack on the back (one more hole) could connect that to a shielded wire running to the core. That way you can have a remote box that you could tie anywhere with a strap, or have the switch built into the axe, and you can sit the guts of the box somewhere more convenient.

Is this making any sense?

Electronics guru types do you reckon this would be OK? I can't imagine that the noise involved would be enough to interrupt a DIN (maybe an AIN, but) and the resistance of the wire shouldn't be too much, right? Maybe using the DIN module would help this be driven more cleanly?

[MRE]

to just drive A/DINs, you wouldnt even need shielded cable for at least.. 50 to 100 feet.  There is some voltage drop to think about, but thats not really an issue below 20 feet or so.. more than enough for your project.

An idea might be to mount an Ethernet jack on the back or side of the guitar, and on your midibox. This would give you 8 conductors for controls. Which would mean 6 switches, or 6 buttons, or 6 pots, or some combination.

Make one conductor Positive 5 volts, one conductor ground (both 'sent' from the core box), and that leaves you 6 conductors to work with.

I would advise that your positive and ground are the two wires normally associated with crossover cables. That way, if you AXEdentally (pun pun :) plug in a cross over, nothing will be damaged, your buttons, switches, and pots will just behave opposite of normal.

Arcade games use Pots on the end of phone cords of up to 20 feet with no ill effects. You do have to take care of your cords though.