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MSGEQ7-Based DIY Audio Spectrum Analyzer for BADASS Display

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Etmax
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Re: Nice chip
Etmax   7/10/2014 10:01:46 AM
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I read the headline and thought that must be another one of Max's ideas :-) neat chip, but I reckon a, ARM M4 could probably do the lot with some tight coding. Of course if you want a low power version difinitely the way to go.

jambrose950
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Re: Re MSGEQ7: Nice chip
jambrose950   7/9/2014 7:04:19 PM
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Thank you.

Mixed Signal Integration has been advertising in the "other" electronic magazine for years now, and Design Ideas, Planet Analog, and Ideas for Design have been published on our products. 

I don't alway read every issue cover to cover, so I could see missing a few of them over the years. 

David Ashton
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Re: Re MSGEQ7: Nice chip
David Ashton   7/9/2014 6:17:15 PM
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@JAmbrose...Good to see you pushing these very natty chips you make.  but it strikes me you have been hiding your light under a bushel - I had never heard of you before now, but will certainly have a look at what you offer.   

(I think you need to pay Max a commission if he hasn't already asked :-)

(PS @Max - if this causes you to get commission, I want a cut :-))

Max The Magnificent
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Re: Re MSGEQ7: Nice chip
Max The Magnificent   7/9/2014 2:34:14 PM
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@rheslip0: Another approach - use the Teensy 3.1 and audio shield from pjrc.com. You only need one processor which is Arduino compatible so you can use the Neopixel libraries.

Actually, you can't use any-old-NeoPixel library -- the ones from AdaFruit, for example, use low-level assembly code to get the timing right. However PRJC also does a NeoPixel library that drives 8 strips using the DMA Engine.

When I last talked to Paul at PRJC, they were still working on the audio library. I'm delighted to hear that it's finished -- I'm designing my BADASS display in such a way that I'll be able to swap out my first-pass solution (chipKIT + Arduino) for a Teensy 3.1-based solution -- it will be fun to play with that -- but one step at a time LOL

rheslip0
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Re: Re MSGEQ7: Nice chip
rheslip0   7/9/2014 2:02:54 PM
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Another approach - use the Teensy 3.1 and audio shield from pjrc.com. You only need one processor which is Arduino compatible so you can use the Neopixel libraries. They have a really nice audio DSP library including up to 1024 bin FFTs for the ARM M4 core. Teensy board about $20, audio sheild about $15. It will blow the doors off your solution:

https://www.youtube.com/watch?v=CblOUmK3oKM

I'm not associated with PJRC but I am very impressed with their products. I beleive they also have a high performance LED strip driver too.

Rich H

 

Max The Magnificent
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Re: Re MSGEQ7: Nice chip
Max The Magnificent   7/9/2014 1:13:50 PM
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@jambrose: We (Mixed Signal Integration) also have a 1/6th octave Low Power Spectrum Analyzer IC; the MSLSA.  The outputs are 6 AC outputs and you can easily cascade the devices.

Very interesting -- I'm printing off the datasheet as we speak...

jambrose950
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Re MSGEQ7: Nice chip
jambrose950   7/9/2014 1:00:41 PM
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We (Mixed Signal Integration) also have a 1/6th octave Low Power Spectrum Analyzer IC; the MSLSA.  The outputs are 6 AC outputs and you can easily cascade the devices.  Here is a link:

http://www.mix-sig.com/index.php?option=com_content&view=article&id=128:mslsa&catid=52


Samples and evaluation boards are available.  

jambrose950
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Re: MSGEQ7 Nice chip
jambrose950   7/9/2014 12:51:31 PM
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Yes, you can adjust the 33 pF and 200 kohm RC values to achieve different clock frequencies. However the filters are quite wide, so the effect would be minimal.   Others have found the interpolation technique  in firmware gives better results. 

Max The Magnificent
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Re: Nice chip
Max The Magnificent   7/8/2014 6:23:27 PM
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@David: However that leads me to my question...with only 7 frequency bands and 2 channels will your BADASS display now only have 14 channels instead of the 16 in the diagram?

Thsi is something I've been pondering -- I think interpolating between two channels to create an additional channel would give me a quick fix. Of course, when I move onto doing all thus in software using an FFT (or similar algorithm), I'll be able to split things up into as many "buckets" as I wish.

 

Max The Magnificent
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Re: Nice chip
Max The Magnificent   7/8/2014 6:20:52 PM
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@Rcurl: I notice that you can set the oscillator frequency of the chip externally. I wonder if you could intentionally skew the oscillator frequency of a second chip being fed the same audio input to get some extra bands in between the intended ones?

Oooh -- that is an interesting idea...

 

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