[dorkbotsyd-blabber] Crushed Glass granular sampler/looper/glitcher

Iain Chalmers bigiain at mightymedia.com.au
Mon May 23 01:58:49 EDT 2011


On 23/05/2011, at 3:41 PM, David Lyon wrote:

> Just not enough channels...
> 
> It would be good to have 50 channels ..

Looks like you could use several of those chips with different resistor/capacitors to tweak the center frequencies so the different chips bands all interleave. Not quite as nice as "doing it properly", since adjacent frequency bands will bleed into each other, but surely it'd be "close enough" for artistic/aesthetic purposes? 

big


> because the doors on the car
> are quite wide and one for the dash also would be good. Although
> a short night-rider style would be ok.
> 
> On Mon, May 23, 2011 at 3:34 PM, Mr Aras <aras.vaichas at gmail.com> wrote:
> That chip is awesome. Very handy!
> 
> 
> On 23 May 2011 15:32, David Lyon <david.lyon.preisshare at gmail.com> wrote:
> Yes, I had my terminology all mixed up but that's what I meant.
> 
> I then found this recent addition which will pbe a start:
> 
> http://littlebirdelectronics.com/products/graphic-equalizer-display-filter-msgeq7-1
> 
> When they came out they were $30+ but now they are down to a reasonable
> price.
> 
> My door panels in my car are boring - need to add some colour.
> 
> I once bought a car solely because it came standard with a graphic equaliser.
> 
> Thanks for those links - very helpful ! I will be studying them more closely.
> 
> 
> On Mon, May 23, 2011 at 3:24 PM, Mr Aras <aras.vaichas at gmail.com> wrote:
> I think you mean a "spectrum analyser". A graphic equaliser is a panel with slide pots that allows you to alter the level of individual frequency bands. e.g. http://www.dbxpro.com/1231/index.php
> 
> Is this what you're after?
> http://www.youtube.com/watch?v=BoWRUcCCsjM
> http://www.youtube.com/watch?v=BtkPDLJpEbQ&feature=related
> 
> LCDs aren't very bright, I recommend using LEDs.
> 
> The basic filtering algorithm is IIR or FIR filtering, but it's not really basic and there is a fair amount of work and programming to do it this way.  If you're using a PC, most patching packages should have a plugin for finding the power level at each band.
> 
> The alternative is to build a bank of analog band-pass filter + peak detectors, feed the outputs to the ADC inputs on an arduino. The analog BPFs use capacitors.
> 
> Try this: 
> http://www.youtube.com/watch?v=ja5NUoVEktk
> "Spectrum Analysis Circuit using an Arduino and a Max 7219
> I think this one uses a PC running Processing to find the band levels and then it uses the Arduino to display the levels.
> 
> Aras
> 
> On 23 May 2011 15:11, David Lyon <david.lyon.preisshare at gmail.com> wrote:
> speaking of this stuff, i want to make a very big graphic equaliser
> using rgb lcd's and 'duinos for my door panels.
> 
> Basically, i want each door to have the fabric area replaced with a
> graphic equaliser.
> 
> Whats the basic filtering algorithm for that? Is it capacitors?
> 
> 
> 
> On 5/23/11, Mr Aras <aras.vaichas at gmail.com> wrote:
> > It would be very tricky to do that on the AVR because the SPI port isn't
> > double buffered AFAIK. You need a proper synchronous serial port which Atmel
> > call "SSC" for Sync. Serial Controller.
> >
> > If the SPI port isn't double buffered you can't send bytes back-to-back and
> > since the signal in synchronous any slightly glitch in the signal could
> > cause clock problems. Worth trying though.
> >
> > On 23 May 2011 14:28, Iain Chalmers <bigiain at mightymedia.com.au> wrote:
> >
> >>
> >> On 23/05/2011, at 2:09 PM, Mr Aras wrote:
> >>
> >> > I've been looking for the same thing so I will share my notes:
> >>
> >> Did you see this:
> >>
> >> http://scanlime.org/2011/04/spdif-digital-audio-on-a-microcontroller/
> >>
> >> S/PDIF Digital Audio on a Microcontroller
> >>
> >> basically using the high quality DAC that you've probably got hidden
> >> inside
> >> your hifi amp to get audio out from your own hardware.
> >>
> >> Specifically this bit:
> >>
> >> "Microcontroller Implementation
> >>
> >> Typically if you were generating an S/PDIF signal, it would be sane to use
> >> an FPGA or an ASIC. In silicon. But this article is about breaking the
> >> mold
> >> and doing it in pure software. Why? For fun, and maybe also to lower the
> >> barrier to entry on digital audio. There are a few challenges to overcome,
> >> though:
> >>
> >>        • Need to have enough CPU left over to generate the audio signal in
> >> the first place
> >>        • Very high bit rate for a software implementation
> >>        • Strict bit timing, at an unusual frequency
> >>        • Biphase mark encoding is not parallelizable
> >> My platform of choice for this project was the multi-core Parallax
> >> Propeller, since it’s simple and hobbyist-friendly yet it also has
> >> features
> >> which directly address these challenges. The XMOS XCore, another parallel
> >> microcontroller, would also be a fabulous choice. It may also be possible
> >> to
> >> implement S/PDIF on a sufficiently fast single-core microcontroller.
> >> Unfortunately, an 8-bit µC like the AVR used in the popular Arduino board
> >> probably wouldn’t be fast enough.
> >>
> >> Edit: Actually, perhaps it would be doable on the Arduino after all… you
> >> would just need a less common crystal frequency. To generate an S/PDIF
> >> signal with a 32 KHz sample rate, for example, you could run the AVR at
> >> 16.384 MHz. The encoded bitstream clock would need to be 4.096 MHz (32k *
> >> 64
> >> * 2), and you can program the AVR’s SPI master to transmit at up to half
> >> the
> >> main oscillator frequency. So you could run the AVR at 8.192 MHz or 16.384
> >> MHz. At the latter frequency, you would have 32 instructions for every 8
> >> bits of encoded bitstream data. That should be enough to do the encoding
> >> in
> >> an ISR and have a little time left over for applications…
> >>
> >> A multi-core microcontroller makes challenge (1) a piece of cake. On the
> >> Propeller, one of the eight CPU cores can be dedicated to S/PDIF encoding.
> >> The other seven are available for application code, sound streaming or
> >> synthesis, and for other I/O devices."
> >>
> >> big (with too many other un-worked-on projects to get too involved in
> >> this)
> >>
> >>
> >> >
> >> > * Analog have a range of DSP chips:
> >> http://www.analog.com/en/processors-dsp/products/index.html  It's fairly
> >> high-end stuff though. I'm sure they have devkits. I'm not sure if these
> >> CPUs are covered by GNU tools, you might have to pay for the development
> >> tools. The SigmaDSP looks interesting:
> >> http://www.analog.com/en/processors-dsp/sigmadsp/processors/index.html
> >> >
> >> > * many micros offer DSP-like features. e.g. MAC -
> >> > Multiply-and-Accumulate
> >> (used for digital filters). So you don't necessarily have to get a "DSP"
> >> as
> >> such.
> >> >
> >> > * DSPs are efficient at maths, but any fast microcontroller can do the
> >> same thing by virtue of speed
> >> >
> >> > * Arduino can do easily do lo-fi audio DSP. A 16MHz CPU can do 32KHz
> >> sample rate, 8 bit in, 8bit out, 500 instruction cycles per sample, that's
> >> a
> >> lot of time to manipulate the audio and do some great stuff. Don't
> >> underestimate it!
> >> >
> >> > * 8bit and 32bit micros cost about the same now. The price difference is
> >> reflected in the memory - FLASH and SRAM. For DSP you might as well go
> >> with
> >> a 32bit CPU. i.e. ARM, AVR32, etc
> >> >
> >> > * most micros will have, at most, 12bit ADCs and 12DACs. DACs are very
> >> rare on the low end models, it's more of a mid to high end feature.
> >> >
> >> > * if you want hifi audio, you need a dev board with a CODEC chip and
> >> > then
> >> you'll have your 44.1KHz/channel 16/24bit standard. e.g. audio CODECs from
> >> TI:
> >> http://focus.ti.com/paramsearch/docs/parametricsearch.tsp?family=analog&familyId=583&uiTemplateId=NODE_STRY_PGE_T
> >> >
> >> > * Once you choose to use a CODEC, you don't need the DAC on the micro
> >> > any
> >> more. ;)
> >> >
> >> > * To interface to a CODEC you need a micro with an I2S port. Low-end
> >> won't have them, it's a mid to high end range thing.
> >> >
> >> > * I have seen people hook up CODECs to AVRs, but I've not seen anything
> >> that is commercially available
> >> >
> >> > I'll keep looking for myself and post anything that I find which could
> >> > be
> >> of interest.
> >> >
> >> > Aras
> >> >
> >> > On 23 May 2011 12:51, Nicholas Mariette <nmariette at gmail.com> wrote:
> >> > Just wondering what sort of DSP dev kits people can recommend that are
> >> suitable for audio 1 or 2 ch I/O?
> >> >
> >> > I'm a little out of the loop on the latest offerings since about 2007.
> >> >
> >> > Approx prices would be great too, and suitable online vendors...
> >> > — Is Sparkfun still one of the better vendors for this kind of thing?
> >> >
> >> > Anything from more general purpose Atmel, ARM to stricter DSP would be
> >> interesting, so long as there is audio DAC and ADC built into the dev kit.
> >> >
> >> > best bang for the buck ideas would be great too.
> >> >
> >> > TIA!
> >> > Nick
> >> >
> >> >
> >> >
> >> > On 23/05/2011, at 12:20 PM, Mr Aras wrote:
> >> >
> >> >> http://www.youtube.com/watch?v=TRflDaVqfuQ........................................................................
> >> >> .........dorkbot: people doing strange things with
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> >> >
> >> >
> >> > ........................................................................
> >> > .........dorkbot: people doing strange things with electricity..........
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> >> >
> >> > ........................................................................
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> >>
> >> ........................................................................
> >> .........dorkbot: people doing strange things with electricity..........
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> >>
> >
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> 
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> .........dorkbot: people doing strange things with electricity..........
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> ........................................................................
> .........dorkbot: people doing strange things with electricity..........
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