Hello

I got one e-mail [ [url]http://casainho.net/tiki-view_forum_thread.php?comments_parentId=2&topics_threshold=0&topics_offset=0&topics_sort_mode=commentDate_desc&topics_find=&forumId=1 ] from one guy offering work to the Homemade MIDI turntable Open project.

We would like to make one TODO/wishlist list.

If anyone want to check the project page and give some ideas, we appreciate.

Thank you.

JPCasainho - www.Casainho.net

Hello

My name is Jorge Pinto and I am from Portugal. I am electronics professional and I like to develop hardware.

I am doing a cheap(+-30 Euros) and simple "Homemade MIDI Turntable" to connect on PD.

I am looking for information on others projects similar and feed-back, ideas, etc...

I hope to release the final version very soon with GPL licence.

Please tell me what you think about and give me suggestions. Thank you.

Home page of project in English with one video: http://casainho.net/tiki-index.php?page=Homemade%20midi%20turntable

Casainho
http://www.Casainho.net

hello

I am looking for cheap and quick hardware input for Puredata. I am using Linux Ubuntu.

Well, I already tested with success, one tablet, joystick, keyboard, midi in, mouse..

But I am looking a way to do some electronics to work in Puredata. Anyone knows if I can use parallel port in Puredata?? Parallel port would give 8 digital inputs and 8 digital outputs.

Well, I am searching about midi protocol and It's trivial to implement on a controller as an ATMEL with GCC-AVR however, MIDI to USB devices are expensive

Well, also I want to do a turntable to control Puredata and I am looking devices, potentiometers, electronic rotors , etc.. I apreciate any link with info - thank you.

To share with you:
http://wiki.dorfeu.com/tiki-index.php?page=Ani

If anyone need that code, I can share.. I am just waiting to share the v 1.0

How much are they per chip? And if you make the PCB, roughly how much does the total cost of the board and uC come to?

Microcontroler ATMEGA8 ~6 euros. The circuit is very very simple, so, PCB should be very cheap!! Here is an image of the circuit: http://casainho.net/show_image.php?id=77

Board + uC, maybe about 15 euros. But, there is the need of MIDI<->USB converter, more about 30 euros. So, no more than 50 euros the electronics of the project.

I had an idea for that... just use an electric motor, most have holes for mounting tapped into the front already and you get two really good bearings (one in each dime) for the price of one. Plus you can pick up motors for almost no money. Just because you're not going to use the motor to drive it - you can stil use one

Good!! I will start to looking at motors repair shops in my city, maybe I can find bearings, shaft and metal plate already mounted

People who will test this and give you cool feedback are DJs, whether they are Pd users or whatever. The reason I suggest Reaktor is nothing to do with that software really (although it is a good choice because Reaktor has OSC) but because there are lots of people who use it who are
probably also DJs while Pd has a few, probably less because it is more cerebral (no offence meant to any DJs).

I don't have any DJ friend in my city and I am not a DJ... It's a difficult to find someone and get good feed-back.

How about to create a good solution for DJing, with PD and with this hardware? - A patch for PD and this hardware? - maybe more DJs would approximate from PD...

A question, can you please tell me in what ways can I communicate with PD? MIDI, netsend?? - OSC is not build in PD default installation, right? - I would prefer something that is already on PD...

About Makezine, I think I will wait sometime, get something more robust and contact them to publicity the project.

@casainho said:

The optical sensor was chosen because is really cheap, easy find on local shops and have good detection of movement.

That's a really good design I think, not just cos it's cheap but because it's clever - robust, reliable, no physical or electrical contact!

Question: How are you going to mount the optical sensor? Will it read from the edge of the platter or will it shine down on the surface?

Ok, the optical sensor is really nice because of that you said, however, there is one dificult, as you may know, the mouse must be really near from the mousepad or the surface... so, the mouse must be really near from the plate!!

Putting mouse on the surface, I think It's not good because applying force to the plate when turn it to rotate, may change the distance from plate-to-mouse.

The distance from edge of plate and mouse should not change very much when applying force to plate. Also in the edge we get the highest resolution measure of the mouse, of the optical encoder - I think that there is more resolution than needed

First of all, let me real "thank you" for all your words! I appreciate.

@obiwannabe said:

> What protocol should be used to communicate with PC??
> MIDI isn't slow?

MIDI is not just a protocol, it is an entire communication system from the physical layer right up to the data layer including baud rate and connector specs. MIDI as a protocol could be run much faster over USB2 or ethernet, but a sensible modern extension to MIDI would encapsulate it inside OSC or something like that and send it over a session aware layer. MIDI has had 20 years and now it's probably best to just bypass it and go straight for OSC over ethernet. That would also bypass all those "driver" issues for Windows users too.

Okok, I understand. I will look at OSC

However, I am looking for a cheap and simple way to communicate with Pure Data, without the need to write any special driver for Pure Data and OS.

@obiwannabe said:

> I plain to use Linux!!

An excellent choice if I may say so sir! Perhaps it's time to look at Linux SBCs with built in network and USB. You can get tiny ones that are no bigger than a matchbox and single chip FPGAs that you can write your software into. Check out http://linuxdevices.com/

Eheh - I plain to use Linux on PC, with Pure Data, so the communications protocol should at least work very well on Linux.

About hardware, I am already using a microcontroler(not an FPGA, I have no knowledge for that but I would like) with C programing but with a RTOS, Real Time Operation System, in this case, the FreeRTOS, with a license alike GPL

I must say that for now, this microcontroler with C and with FreeRTOS is more than enough

@obiwannabe said:

> I am having problems in getting an turntable to electrify with this
> electronics hardware

You will not drive a turntable motor from USB. The current demands will kill the source. You need an external PSU. 12v at about 1 amp is probably plenty.

No, I didn't explained myself well

The problem is to get a cheap turn table!! For cheap and simple project, It will not have any motor... Its more just a circle that we can turn right or left, more quick or not...

@obiwannabe said:

> Should this project be commercial?? I would pay to someone that made for myself
> the turntable in wood, plastic or metal. Where can I find such shop?

In your garage. ...demonstrates ingenuity in using the optical sensor, but you need to very clearly define the exact function and software it is designed to work with and why.
... Choose the biggest group like Reaktor users and build it for them.

I want to build especially this project for Pure Data, because Pure Data is Free Software and I think is great, fair and the way I think.

I would like that this project grow with Pure Data community help, for Pure Data people, so, I would like that It be simple and cheap.

The optical sensor was chosen because is really cheap, easy find on local shops and have good detection of movement.

I just talked about commercial project, because It would be simple, more accessible to Pure Data community If anyone could buy already assembled or at least the parts to assembly.

What I have difficult now is to get an kind of turntable in wood, just a simple base in wood with a circle that turns left and right...

Thank you for your wisdow

obiwannabe, Thank you.

Later I will ask you for that demo.

Some questions:

• What protocol should be used to communicate with PC?? MIDI isn't slow? - I plain to use Linux!!

• Should this project be commercial?? I am having problems in getting an turntable to electrify with this electronics hardware - I would pay to someone that made for myself the turntable in wood, plastic or metal. Where can I find such shop?

@casainho said:

Home page of project in English with one video: http://casainho.net/tiki-index.php?page=Homemade%20midi%20turntable

I would like to have some simple patch for testing the machine. Some that plays one music and that let me moving forward and backward in the music with that MIDI values... can anyone help me with that patch??

Thank you.

@obiwannabe said:

[hid] maybe ?

I used with success the "linuxevent" with my tablet, and I got x-y position and pen pressure

Recently, I tried to install PureData and I could not install "linuxevent" - but I think that HID object is more update... however, I don't know how to use It, since the is no help file

Anyone knows how to use HID object?? - thank you.

My project where I use my tablet:
http://casainho.net/tiki-index.php?page=Ani+-+Graffiti+digital

@obiwannabe said:

I don't understand something, is the shaft encoder on the motor spindle? Is the table a belt or rim drive?

Well, I don't have the encoder yet, I just saw his datasheet. I already look at the old vinyl player and I hope to put the encoder directly on the shaft.

Maybe I will have a problem, because the encoder is very cheap, about 15 euros, so, It just give 128 positions per turn

I remember to see a good encoder, for 6000 positions per turn, for about 250 euros!!

I am looking for simple and cheap hardware to detect the position of the shaft.

Other thing, is, should I send position, velocity and acceleration to Puredata?? or just position?? - since the Microcontroler can do all that work...

The hardware is very simple: Old Vinyl turntable + Encoder + Atmel ATmega16 + MIDI -> USB.

. Encoder, can be expensive but starting at 15 euros.
. Atmel ATmega16, the Microcontroler, for 4 euros or less.
. General MIDI <-> USB for about 25 euros.

@obiwannabe said:

Would be nice to hear some scratching of samples on this when you
finish it.

Oh, I don't scratch, I am constructing my toys - So I will need feed-back... I will give the project for free and try to make It simples with a manual hopping that people construct and use It, and I will have feed-back then

@obiwannabe said:

My understanding of this is that it isn't timecode. It's just a recording of a sawtooth wave. In theory it's quite doable in Pd and without a fancy soundcard. You just need to get the pitch (using something like [fiddle~]) and the direction (slope of the input), so that you know whether the turntable is moving forwards or backwards. From those you have the rotational velocity, which you can then use to index a sample playback table.

Please see my post about my My Homemade MIDI Turntable

Thank you.

Casainho
http://www.Casainho.net