rasteri

Here, have some pics http://picasaweb.google.com/rasteri/Scratchtroller I'm in the process of updating the wiki page too.

Works now ;D I just put the cap sensor through a DIN* like you suggested. That means I can have MIOS_AIN_NumberSet set to 3 - and this tracks the wheel perfectly. I'll post code in a bit. (* - actually just to RD1, and I'm strobing RB4 myself. Fuck shift registers!)

Wow, that's what I call helpful... thanks stryd, I'll give that a go when I finish work.

I'm having a problem - I need another AIN input for the capacitive sensor but if I change MIOS_AIN_NumberSet to 4 then it stops tracking the wheel properly. I guess it must be polling the photodiodes too slowly. I tried setting the T0CON prescaler to 1:2 (instead of 1:4) in the MIOS source, but that doesn't seem to have made any difference. Any ideas? Should I start another thread for this? (BTW, I'll get a step by step howto up as soon as I get it working properly :P)

Now got a aluminum foil capacitive sensor on the wheel so the song keeps playing if you let go. bNtCZN97R3I I think that's basically all we need, now to start building it into something that isn't made of cardboard and duct tape. (When I get paid).

Don't get me wrong - I would of course release plans, code, and schematics under the GPL/CC or similar, even if I were to write my own MIDI code. BUT - I would also like to sell assembled units to people that cannot make their own, which I understand is forbidden under the MIOS license. Hence the need to rewrite. I don't share the philosophy that you should have to be an engineer to make use of this stuff. I have other reasons - I want to design my own PCB with everything on one board, not the normal MBHP way of having multiple boards (Core, AIN, DIN...). This would need some parts of MIOS to be rewritten ANYWAY, since I won't be using shift registers, and I want to be able to use (for example) the LCD pins as switch inputs. (something I think MIOS should be able to do anyway BTW) Anyway, I hope you guys interpret my motives as good. As I said before, the last thing I want is to piss off the people who have helped me so much.

How would the MIDIBox community view rewriting one of my MIDIbox-prototyped projects to have no actual MIDIBox code in it, and then selling it as a product? None of my current projects are anywhere close to that stage yet, but possibly with a lot of features and refinements they could be made into products, or kits, or something. I realise there probably aren't any legal issues with this, but would it be considered acting in bad faith? I've had (and will hopefully continue to get) lots of help from the MIDIBox community both in this forum and the chat room, and I don't even wanna start planning to sell stuff if you guys would think I was just making cash off your advice.

Hey just to let y'all know I'm still working on this. Latest plan is to have a slightly-bigger-than-12" encoder wheel glued to a real piece of 12" vinyl. The LED/photodiode would then be mounted on a real turntable. I decided I'm not really good enough at construction to do it any other way. It also has the advantage of being portable to any club with a turntable. It could be mounted in the 45RPM adapter hole, or the lid hinges, for easy installation/removal. Easier than wiring up Serato in the middle of the previous guy's set, anyway.

The Infinium is about $30. It's non-contact. I've never used one though. The CF-PCV which I used goes for about $80. Contact faders tend to be more expensive - and crappier. You could probably use any fader that was nice and loose, but it won't last long if you use it for scratching. Here's a quick schematic. schematic.PNG

http://www.midibox.org/dokuwiki/scratchcontroller It's mostly just waffle right now but I'll have schematics up as soon as I can.

Here's the code if anyone's interested. main.c main.c

The drifting was caused by the DJ program I was using (mixvibes), it seems to ignore very small movements. This was naturally causing the audio to go out of sync with the wheel. Switching to Traktor 3 fixed it. There are 250 grooves in the encoder wheel, so that gives 1000 points per turn (one per edge transition). I'm going to mount the whole thing on a spindle and use a real piece of 7" vinyl as the scratch surface, maybe I'll use a bigger encoder wheel. The difference in sensitivity from a real vinyl doesn't really matter, I mean if you're a turntablist you're used to scratching on different speed platters anyway (33/45).

I've fixed the drifting problems :) (and stuck a DVD on top to make it easier to grip) It really feels/sounds like scratching on a tiny piece of vinyl, I really didn't expect it to work this well. Here's a freestyle session I recorded earlier - http://www.youtube.com/watch?v=voVn0QNAyG0 - the crossfader is MIDI too btw.

The disc is 16cm in diameter, just smaller than a 7" piece of vinyl, which I'll try mounting underneath it on a spindle. I'm going to stick the whole thing on something like a harddisk motor. It feels very responsive, on the same level as a CDJ-1000. I'm a pretty good turntablist and I would be happy scratching on it for hours. There's a few problems to work out though, for example the cue point keeps slipping, and the disc isn't big enough (for me). The resolution seems fine, in fact I'm thinking about lowering the resolution as the sensor keeps missing grooves. Or maybe it's because the slits in the pattern aren't the right size for the sensors. This is the first time I've ever made an optical encoder...

Works Great ;D Bq3QkT22ieU (crossfader not shown)

That's creepy, it looks almost exactly the same as what I was planning... ...guess that means the basic theory must work though :)

How about just printing it on a transparent sheet (overhead projector stylie)? Attached is my first attempt, I'll get this printed at a print shop tomorrow (I have no printer!). This should give 360 steps per rotation, which I'm not convinced will be enough, but we'll see what happens. encoderwheel.pdf encoderwheel.pdf

OK now I'm determined to prove this can be done :P Where can I get one of those encoder wheel things? I figure I'll harvest the optical sensor from a mouse or something.

It's a Vestax PCV fader. I borrowed it from my Vestax PMC-06 scratch mixer. They're pretty good, but there are better scratch faders out there, like the Pro-X-Fade, Infinium, or (when it comes out) Innofader.

Hi, I've been working on and off on a MIDIBox-based portable scratching solution. I have a scratch-capable crossfader hooked up to midibox and working fine (http://www.youtube.com/watch?v=h8e2hHiw1fk) and the next step is some sort of scratch wheel. Right now I'm using timecode vinyl and real turntables, which are a bit unwieldy for gigging. This needs to be more than just a simple jog wheel - it needs to be very responsive to slight movements. I figure I'm going to need 256 (or more) steps per rotation. SmashTV sells encoders with 24 steps per rotation and detents, so I guess they're no good. My questions are : 1) Where can I get a higher-resolution rotary encoder in the UK? I can only find industrial suppliers. 2) Would using some kind of gearing mechanism and a lower-resolution encoder be a better solution?

OK, here's the log after trying to upload an application (the revision ID test program : http://www.ucapps.de/mios/revision_id_v1a.zip) : Starting upload of main.hex Received Upload Request Sending block 00003000-000030FF Received Checksum: 38 - OK Sending block 00003100-000031FF Received Checksum: 60 - OK Sending block 00003200-000032FF Received Checksum: 40 - OK Sending block 00003300-000033FF Received Checksum: 60 - OK Upload process complete Then I reboot, and the upload requests just keep coming. Trying to upload MIOS gives a "Upload process complete" message too.

I am trying to upload MIOS onto a 18F4620. MIOS Studio receives the upload requests OK. When I try to upload, I get this : Starting upload of mios_v1_9f_pic18f4620.hex Hex file contains code in MIOS range, forcing reboot! Received Upload Request Sending block 00000400-000004FF Received Checksum: 54 - OK etc.... So it seems to be flashing ok. But when I reboot the PIC, it just goes back to displaying upload requests every few seconds. I've tried uploading an application too, and that didn't make any difference. What could be wrong? Can the PIC be set to read-only?

As luck would have it, a friend decided to pay me a visit, so I got him to go past maplin on the way here :) Thanks anyway. No doubt I'll need your help when I can't get the optocoupler to work...

I'm in the UK. Guess I'll just have to order one from Maplin. Burning MIOS and an app in one hex file using a PIC programmer would be useful though - that means smaller cases, fewer components, faster programming time etc. Wouldn't it be possible to patch the mios hex file from locations 00003000 onwards with the hex from the application? Or does MIOS/the bootloader do some more complex stuff?

Hi, I was wondering if it's possible to upload MIOS and an app (in my case, a custom written C app) to the PIC without using MIDI in? I ask because I have no spare optocouplers and I can't get to any electronics shops in the next week or so. My PIC programmer works fine, I've burned the bootloader and I am getting upload requests from the MIDI out. Alternatively, is there any quick way of interfacing the PIC to the midi port without using an optocoupler? It's not permenant, just to get one program loaded....