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skaurus
07-18-2016, 06:08 PM
Hi!

I am looking to build yet-another sound-reactive wearable project (t-shirt with leds) for upcoming trance music festival :-)
This is my first experience with Arduino's or microelectronics at all. No wonder I have a list of questions I need to find answers for to build it. I am trying to research it myself as well as I could but sometimes, being a novice, I have to ask others.

So, maybe you could give me some input about what microphone should I choose? It seems they all not that expensive so lets try to rule out price. I need a good resolution for doing FFT, low noise and it must work in a loud settings (festival after all...). Generally - best quality small-size microphone :-)
Most probably I would be using Teensy 3.2 with it. Amazing possibilities for its price, size and power requirements!

At least at what specs should I look? Electret, mems, other type? Maybe "big" one like lavalier would work even better?

PaulStoffregen
07-19-2016, 12:41 AM
Probably best to start with the normal electret mic and the audio shield.

http://www.pjrc.com/store/microphone.html

For use in a wearable project, especially worn while dancing at a festival, the way to position the mic will make far more difference than the type of mic. Even these cheapest electret ones will have a noise floor that's far less than the noise you'll pick up from ruffling of clothes & costumes.

skaurus
07-19-2016, 01:29 PM
Hm, can't found SPL acoustic overload point of this mic. I am afraid that sound about ~120dB will be too much for it...
https://www.tindie.com/products/onehorse/ics43432-i2s-digital-microphone/ looks much more promising. And I won't need Audio Board for it, right?

Thank you for input about ruffling and all! Didn't thought about it.

PaulStoffregen
07-19-2016, 01:39 PM
I do not know if that mic works with the audio lib. It might, or it might need a longer than 16 bit word format. The page says 24 bits. I can tell you the I2S code we have now uses 16 bits per LRCLK phase, not 24 or 32.

To get started, I recommend the well traveled path of the audio board and electret mic. You can always try to switch to a different mic later. By then, you'll have gained quite a lot of experience with the rest of the project, which should make these decisions clearer.

skaurus
07-19-2016, 02:07 PM
Oh. Not so promising then!

I will follow your advice. So, Teensy, Audio board, two 14x1-D pins and microphone?

edit: um, my time requirements and your shipping prices are quite incompatible it turns out! I've ordered Teensy and Audio board from another seller. No double insulator pins though... I'll think up something :-)

skaurus
08-03-2016, 05:09 PM
Hello again.

Does 3.5" input jack on Audio board have "Plug in Power"? It is required for some external microphones.
Also it may be useful to know - is this jack wired OMTP way or CTIA / AHJ way?

MichaelMeissner
08-03-2016, 05:30 PM
Note, the 3.5" jack on the audio board is an output jack for sound output to headphones. There are line in pins and pins for a microphone, but these don't include a power pin.

skaurus
08-03-2016, 05:55 PM
Thanks for your reply.

Oh. So to connect some external microphone I will have to solder appropriate jack?

MichaelMeissner
08-03-2016, 07:16 PM
Thanks for your reply.

Oh. So to connect some external microphone I will have to solder appropriate jack?
Yes, or at least solder wires to connect to the microphone. There is a microphone input/ground in the center of the board, plus left/right line-in pins on one side. I would imagine you could also hook up an i2s microphone to the audio shield.

If you wanted a basic microphone, PJRC sells one with a little custom washer that is made for the audio shield: http://www.pjrc.com/store/microphone.html

Onehorse makes a i2s microphone that is meant to attach to a Teensy, but I don't know if it would work with the audio shield: https://www.tindie.com/products/onehorse/ics43432-i2s-digital-microphone/?pt=full_prod_search.

defragster
08-03-2016, 07:26 PM
@MM - the onehorse i2s mic was noted above p_3 - it is 24 bits ...

Question: The MIC section I assume has a suitable amp circuit to support the electret mic? What levels are 'line in'? My limited understanding suggests the line in would expect something driven to the level of a 'Mic on a breakout' with needed pre-amplification?

Also not sure if I read this right - but was it once stated - in this context - that the headphone output shouldn't be put into a amplifier system of a typical pc speaker system type arrangement?

skaurus
08-03-2016, 08:09 PM
If you wanted a basic microphone, PJRC sells one with a little custom washer that is made for the audio shield: http://www.pjrc.com/store/microphone.html
Well, I had to order Teensy from another store and they didn't have this mic.
And then I found that for most of the mics I could buy near me (I'm outside of the USA) I can't even find datasheet.
Maybe I just don't know proper stores here, but anyway, I wasn't bothered much since I was going to use lavalier microphone with mini jack (1⁄8 in) for better quality.

Now, it turns out, it isn't so simple :-) Can you confirm that I can (or can't) solder mini jack to line in R + L + 2xG pins and connect external microphone to it? Will it work or I will need some kind of amplifier or what else? If yes (I hope so!) maybe you can explain what solder to what? I find it hard to find microphone jack pinout :confused:


Yes, or at least solder wires to connect to the microphone. There is a microphone input/ground in the center of the board, plus left/right line-in pins on one side. I would imagine you could also hook up an i2s microphone to the audio shield.
I guess MIC+GND pins are for microphones like from PRJC store only, not for "big" ones with mini jack?


Onehorse makes a i2s microphone that is meant to attach to a Teensy, but I don't know if it would work with the audio shield: https://www.tindie.com/products/onehorse/ics43432-i2s-digital-microphone/?pt=full_prod_search.
Yeah, I know... Maybe it was a mistake to not order it at the same time as Teensy and now I can't - due to my project time restrictions :-(

MichaelMeissner
08-03-2016, 08:45 PM
Somebody who knows the electronics more than me will have to answer those questions.

skaurus
08-03-2016, 09:49 PM
Thanks anyway :)

skaurus
08-04-2016, 01:33 PM
Maybe I can solder microphone audio jack directly to MIC+GND pins and it will work?

skaurus
08-06-2016, 09:18 PM
Maybe I can solder microphone audio jack directly to MIC+GND pins and it will work?

Yes! I soldered audio jack, inserted microphone in and it works!
And pretty well :-)
Cheap random lavalier model: Panasonic RP-VC201