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Everything else / Midi controllers
« Last post by Leighton on December 29, 2017, 04:18:33 PM »
I'm a new owner of a splendid Atmegatron, which I picked up as part of the B-stock sale. Sweet.

I got this to use in performance with my wind synth (Yamaha WX11)  and it works fine.
I was looking into getting a small keyboard controller and I noticed that many rely upon USB bus power, so I'm guessing they would not work with a straight midi plug usage? I'd be curious to know if there's a work around for this, like plugging into a powered USB hub just for power? Or if there are better solutions. I'd like to have a simple set up for live performance and not have to bring a laptop just to power my controller.

I'd also be curious to know what everyone else is using for a controller for the Atmegatron.

miniAtmegatron / Re: Is Miniatmegatron open source?
« Last post by veryfungi on December 29, 2017, 02:30:05 AM »
Hi Paul,

Thanks for your help. I had already ordered my pc boards, I should have them in a few days. After I verify it works I would gladly share the files. I can provide the gerber files or the eagle files. Bear in mind I just tossed the board together and didn't start with a schematic first. Lesson learned.

I can add the pads for serial no problem, and any other mods needed. I may start over in eagle with a proper schematic. :) I did want to ask you. In an effort to make it a bit more eurorack standard, I wanted to convert the 0-5v audio to 5vpp. I made the board in a way that it can be wired in two ways. It's been a really long time since I studied op amp circuits. It can be wired to pass the dc to the 702 with 2.5vdc on the + input, or put in a capacitor in place of J1, jumper R2 and leave R1 out. Which method would you recommend?

PC boards are really cheap. I have time to work on it, and it looks like fun. Thanks
miniAtmegatron / Re: Is Miniatmegatron open source?
« Last post by paulsoulsby on December 28, 2017, 01:26:36 PM »
Wow I didn't even know about that setting - that's bonkers!  I've located it and updated it to a luxurious 1Mb per pic!

Nice PCB - that's got me think about the possibility of an expander board that allows CV control over the parameters. I'd be tempted to put the Arduino serial pins (digital 0 and 1) on a 2 pin header that can be added as an option. This would then allow an expander unit to be connected which would provide more modular friendly inputs.  Use the 6 analogue inputs for CV and some of the free digital inputs for gates.  Then convert them to MIDI CCs which is transmitted over serial to the Euro-Mini.

I might even be tempted to develop that next year if there was a demand for Eurorack miniAtmegatrons! Def worth sticking 2 pads on the PCB for pins 0 and 1 (on a standard 2.54mm 2-way header).

Anyway, just a thought!
miniAtmegatron / Re: Is Miniatmegatron open source?
« Last post by veryfungi on December 26, 2017, 11:13:41 PM »
128k max jpg is hard to do. lol
miniAtmegatron / Re: Is Miniatmegatron open source?
« Last post by veryfungi on December 26, 2017, 11:04:45 PM »
forgot to mention, it's hp-20

I will share the files as well.
miniAtmegatron / Re: Is Miniatmegatron open source?
« Last post by veryfungi on December 26, 2017, 11:00:44 PM »
Hi Guys, I wanted to do an update to my project. A little background. I have been amazed by synths since I was 14. I was very poor and although I did make a few things back in the day, they were really basic. Fast forward from 1975 to now. I have the time and resources to finally make a cool synth. I wanted to start by making one of these and move on from there making a full modular synth myself. When I started working on the pcb I was also researching where synths are nowadays. I learned about eurorack and decided that was the direction I would go. I know the miniAtmegatron isn't a true synthesizer module, but I wanted to get accustomed to making eurorack pcb's and faceplates anyway, so I decided to make the miniAtmegatron into a eurorack format. I have the pcb pretty much ready to order, and a pretty good idea what I want the faceplate to look like. The only modification I made was to remove the 22uF cap, and add in a TL702 in a level shifting amp. The schematic is a mess on paper, but it's basically powered by +/-12vdc + input goes to voltage divider providing 2.5vdc. signal enters through a 50k on - input and 100k feedback to - input. Then the 22uF cap added back to the output. Trying to convert 0-5 into +/-5. I will post a schematic soon. :)

On the aspect of getting more pots on there. Why not add an i2c a2d with 12-16 channels and be done with it. It would have to make coding simpler.

Um can't find a way to tell this thing to upload the images...
Everything else / Re: Post your songs!
« Last post by ToyKeeper on December 12, 2017, 09:30:41 AM »
The main difficulty I ran into with this setup is that the KP3's effects don't have key tracking.  ... I may see if I can patch the Atmegatron through a Microbrute instead.

... you can control some parameter of your kaos pad (x-,y-axes) by definable CCs from your arturia keystep or even OP-1

I went the Microbrute route, and it works very nicely with the Atmegatron.  I can basically treat the Atmegatron as another oscillator, using all the same processing that its built-in oscillators go through.  If I send identical midi to both devices, they stay completely in sync and I can even use key tracking.

It sounds pretty good by itself, but if I want to add extra depth to the sound I can turn on the built-in oscillators at the same time.  This adds a whole nother dimension to the Atmegatron, combining 8-bit digital sounds with retro analog waveforms to expand the sound and make it growl.  And, of course, it still goes through the KP3 for a variety of other effects.

Now I just need to get a DAW set up so I can finish the last few songs I started...
Odytron / Re: Odytron updates
« Last post by rio on December 09, 2017, 12:38:32 AM »
Many Thanks!

Best Regards, rio
miniAtmegatron / Re: Is Miniatmegatron open source?
« Last post by bobo on December 07, 2017, 07:22:53 PM »
This helps enormously, thanks. I don't know the MCP3208 ADC. I planned to:
- remove the RGB LEDs, that frees up pins D5, D6, D9, D10 and D11, and remove the switch, that frees pin D2
- add a multiplexer 74HC4051 which takes 3 digital pins and one analog pin (A3), then 8 pots go to the multiplexer and 3 stay on A0,A1,A2
- A4, A5 are ready to act as SDA and SCL to connect to the LCD 1602 board

That leaves me with 3 free digital pins for further expansion.

That seems easy.  :)
Now the software - not so easy  :'(
miniAtmegatron / Re: Is Miniatmegatron open source?
« Last post by paulsoulsby on December 07, 2017, 06:20:39 PM »
Yes, that's work in-progress.  Still trying to find a way to publish it properly.  Also, I think there's possibly too many diagrams, it makes it look more complex than it is!
Start with the Min class.  That contains a hardware class and engine class. The hardware class handles the electronics, the engine is the processing for the generating audio.  Both of those classes generate events.  The job of the Min class is to pass events between the hardware and engine class.  The idea is that the hardware and engine can be totally independent, so you can port different audio engines to different hardware interfaces really easily.
R.e. your customisations.
a)  Yes totally possible. Even can use a Sparkfun MIDI shield (don't connect the buttons or pots though)
b)  You'll need to remove pots on A4 & A5 as they use the I2C bus.  Then add an external I2C ADC chip.  If you look at the code for the Oscitron Hardware, you'll see how to do this with a Microchip MCP3208 ADC.  So 8 of the pots will come off the MCP3208 and 4 off the Atmega328.  That frees up A4 & A5 to use for the I2C to drive the ADC.
c)  See above.  Just free up A4 & A5 and use the I2C bus.  Then adding an I2C screen at a later date is easy too!

Hope this helps as a starting point!
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