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March 25, 2017, 06:30:35 PM
The Stribe Project - ForumGeneral CategoryhellobuildTopic: Foxy's 16 stribe monster - best wat to connect
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fox
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« on: July 04, 2009, 09:40:34 AM »

So, I have 16 Stribes all wired up and soldered... just need to do the links and get the LED driver chips all in -- testing will proceed as soon as Curiousinventor stribe shields arrive I shall get underway...

However I am thinking of the best way to hook it up.

Shall I have two Arduinos and 8 Stribes (one Arduino per) or 13 on one Stribe and 3 on the other with perhaps the remaining channels used for (say) 10 potentiometers?

Thoughts? Ideas?


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ultrajosh
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« Reply #1 on: July 05, 2009, 07:46:00 AM »

For simplest setup I'd say 8 stribes per Arduino.  You're going to have to keep power requirements in mind.  Hey Scott, what do you think about powering 16 Stribe1s?  External power supply?
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curiousinventor
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« Reply #2 on: July 05, 2009, 04:44:03 PM »

First of all, that looks awesome and I can't wait to see the finished animal Smiley

Check out this post I just wrote on brightness and power considerations.  I agree with Josh that 8 per arduino is the way to go.

When stringing lots of Stribe1s together in one past application, I ran into an issue of large voltages appearing across the arduino ground and last Stribe1 ground, because the thin ribbon cable wire had too much resistance.  I was using 6 feet of ribbon cable in that case, however.  You probably wouldn't run into this issue with 13 close together, but it doesn't hurt to be safe. 

My advice is to use an externally powered USB hub.

Another issue is timing.  Every additional stribe1 adds time to the loop due to sampling another analog input, and sending back and forth more data.  At 8 stribe1s, it's a little bit noticeable, and may get annoying at 13.  Splitting it 8 and 8 offloads more work to the computer. 

If you just want a simple relationship between touch and lights, you could always have the arduino take care of drawing instead of the computer, and not have to worry about the usb-serial port slowing down the response. (coding required).  Our current code is set up for maximum flexibility in max/msp.

good luck!

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fox
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« Reply #3 on: July 19, 2009, 04:07:20 AM »

cheers, 2 Arduinos (1 x per Cool it is then. Will address power issues when it all comes together. I may have a spare powered hub that will slip in nicely. Have ordered some acrylics and softpots. I will start to get this mega-Stribe finished before term starts (I am going to be a BA student of Sonic Arts here in London from September) and hope to incorporate this Stribe into my working toolset.

so far I have received the shields and assembled almost all of the MAX7221 compatible LED drivers assembled (pictured are just 3). Just 1 more needed for 8 Stribes and I have started saving and scraping round for the other 16 needed. I am at present building 8 Stribes with Austrian Microsystems AS1107 chips which are *much* cheaper than the MAX drivers.



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ultrajosh
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« Reply #4 on: July 19, 2009, 07:45:17 AM »

Your '16 looks awesome!  I agree a USB hub is the most elegant solution.  You could even de-box it and hide it in your enclosure.  There will be some tweaking on the Max side of things to address 2 stribe8s as one continuous stribe16.

As for the Austrian Microsystems AS1107 vs MAX7221, I briefly looked at the datasheet and they look pretty nice.  But they don't seem to provide an SPI serial interface like the MAX7221.  Also, the power requirement per chip seems a little high (each one requires 500ma?).  Definitely worth investigating and nice find!
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curiousinventor
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« Reply #5 on: July 19, 2009, 09:13:13 AM »

re: AS1107.  Nice find Fox, looks like people are saying it's a pin-by-pin drop in replacement for the 7221. I've got samples on the way Smiley  If they check out, I'll probably start distributing the chips in addition to using them in the Stribe.  Almost $2 per chip cheaper in larger quantities, thanks fox!

I believe it does provide SPI interface, and requires .5mA, not 500mA per chip, which is actually smaller than the 8mA for each max7221.
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ultrajosh
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« Reply #6 on: July 19, 2009, 09:55:56 AM »

oops, I didn't read carefully - well if it's a drop-in and much cheaper that's awesome!
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fox
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« Reply #7 on: July 19, 2009, 10:03:00 AM »

Glad to be able to contribute in some small way.

I'm quite raw to max/msp so I fear a lot of my headscratching will be to rework the 2 x 8 Stribes into one contiguous block...

plus knobs..
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fox
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« Reply #8 on: July 20, 2009, 12:30:16 PM »

I can confirm the AS1107s work perfectly. Assembled 8 x Stribes and ran the spinning flag demo.

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fox
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« Reply #9 on: July 23, 2009, 02:09:53 PM »

Yep AS1107s are just fine... here's a shot to prove it...




The first bank of 8 stribes work just fine.

Now to get the last batch of AS1107s and finish the other stribe bank and I can start to think about casing it and ways to incorporate the 4-port USB hub for the 2 Arduino boards, a gooseneck light for reading onstage and an external port for daisy chaining the Arduinomes.

I want a bit more light from the yellow LEDs so I will also change the resistor settings next.
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ultrajosh
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« Reply #10 on: July 24, 2009, 06:44:08 PM »

In my experience with the original 8-stribe proto, as you reduce the ISET/resistor value (stribe1s ship with 47k ISET resistors) you will start to run out of power from the Arduino's USB port. 

The way I saw this was that all but the last couple of MAX7221s lit up when I used 10k resistors, and then it froze.  So I increased the ISET values to 47k and it solved the problem.

But my point is I haven;t experimented extensively with the ISET value.  One thing I always wanted to try was adding 50k potentiometers in place of the ISET resistors, then tweaking to an optimal setting, then measuring the resistance of the pots and replace with similar value resistors...

Adding an external wall-wart power supply to feed the Arduino might help with power usage, not sure.
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fox
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« Reply #11 on: August 08, 2009, 06:04:33 AM »

Curiousinventor got me some custom smoked acrylics cut for me plus I ordered 16 softpots -- all are cleared for delivery Monday so the next phase of the build is about to begin!

I would at this point like to make use of the unused analog channels on the shields that I am using and (I am assuming I can utilize 7 extra knobs per 8 faders -- I can do a LOT with 14 mapped knobs for fixed parametric sweeps, filters and so on and a centering X Y would be cool too) and I was wondering if there is any additional data on adding these inputs via the stribe shield?
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fox
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« Reply #12 on: August 13, 2009, 08:15:20 AM »

can anyone help with the adding extra knobs information?
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fox
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« Reply #13 on: August 17, 2009, 06:19:11 AM »

Ok got the optimal iset values sorted and am now at the stage of laying out everything logically. I have decided on two groups of 8 faders rather than a single unbroken bank of 16. My mind works that way... There will be the knobs to the right with an additional USB knob from Griffin. This I am adapting to take harsh treatment, scratching and so on. An additional stribe goes between or under the Monomes. I have a special use for that.




Full build pic feed is here: http://www.flickr.com/photos/tanais/
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ultrajosh
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« Reply #14 on: August 22, 2009, 05:45:34 AM »

Wow!  Beautiful!
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