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Topic: Sampling Rate Arduino Galileo (Read 6242 times) previous topic - next topic

lucamagno90

Hi guys,
I have an Arduino Galieo.
I want to use it for samplig audio signal. I don't understand the sampling rate of the ADC.
Can you help me?
Thanks    :) 

Grumpy_Mike

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I have an Arduino Galieo.
You have my sympathy.

 
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I want to use it for sampling audio signal.
We both wish.

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I don't understand the sampling rate of the ADC. Can you help me?
What is there not to understand. The sampling rate is crap and nowhere remotely fast enough to sample Audio. In fact an Arduino Uno is about 20 times faster at sampling than a Galieo.

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Can you help me?
No, it is just a very poor design putting all the I/O through a very slow I2C expander. Forget it.
Sorry.

lucamagno90

ok, thanks for your answer. I read that Arduino Due has a good sampling rate (8khz-193khz), one ADC and DAC.
Maybe, Arduino due will be my answer.

Grumpy_Mike

Maybe, Arduino due will be my answer.
It might be if we knew what the question was.

42


pjrc

I recently published an audio library, which does all this with 44100 Hz sampling.  It only works with Teensy, because fast 32 bit processing and DMA data transfer are needed to support that speed really well.

Maybe this code will help?

https://github.com/PaulStoffregen/Audio

For lower speeds, this site might help you?

http://www.plaindsp.com/

lucamagno90

Thanks guys. But, specifically what is the sampling rate of Galileo??

Grumpy_Mike

#6
Dec 17, 2014, 11:32 pm Last Edit: Dec 17, 2014, 11:43 pm by Grumpy_Mike
about 7-8 milliseconds. Which is about 125 Hz.

I measured it at 1000 readings in 7.5 seconds on my Galileo.

For the Galileo version 2:-
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The Galileo Gen 2 uses a Texas Instruments ADS108S102 ADC, which allows for a 4x increase in ADC sampling performance in Linux compared with Galileo Gen1

lucamagno90

You are right, it's very low. I've read in the adc manual that the freqency sample is 1 Msps. So, sampling rate is not  frequency sample.

pjrc

It takes far more than theoretically fast hardware to deliver a reliable, low-jitter, relatively fast sample rate in the Arduino environment.  Very careful software design is required, to deal with the many Arduino features and library using blocking APIs, and the use of other interrupts by at least serial and timing, and many libraries.

The links I posted in msg #4 show some examples.

Many people have ambitiously tried connecting awesome audio ADCs to Arduino, but failed to get any useful performance when it came to writing the software side.

Do not underestimate the difficultly of fast sampling software development.

Grumpy_Mike

You are right, it's very low. I've read in the adc manual that the freqency sample is 1 Msps. So, sampling rate is not  frequency sample.

The A/D chip is connected through an I2C expansion chip that is only running at 100KHz. It is a piss poor design. I was talking to the designers at the Rome Maker Fair 2013 and they said that they did not realise the chip could not be run faster. Now on the second iteration of the board thy have put on a chip that can run at 400KHz hence it is four times faster but still piss poor. It is just a very badly designed system.

AWOL

The A/D chip is connected through an I2C expansion chip that is only running at 100KHz. It is a piss poor design.
I do wish you'd come down off the fence, stop beating about the bush and say what you really mean.

pjrc

#11
Dec 18, 2014, 03:26 pm Last Edit: Dec 18, 2014, 03:29 pm by Paul Stoffregen
The sad part is Intel could have used a PCIe to some-other-bus bridge chip and then put a 8 or 16 bit parallel bus A/D chip on the board.

Linux supports SPI on chipsets with pretty advanced features, like scatter-gather DMA.  Intel could have used such a chipset and put a fast SPI interface ADC chip on the board.

They could have done a lot of things.  They're Intel.  I'm not sure I'd say "piss poor", but I suppose I expect more from the likes of Intel.

Grumpy_Mike

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I'm not sure I'd say "piss poor", but I suppose I expect more from the likes of Intel.
Yes but you didn't talk to the design team. I did and I stand by piss poor. They had not got a clue about what is important in an embedded processor system. Plus they were only kids with very little real world experience.

heinzV

Well, they did something on it.

download this e-book for free and much of your problems seems to be solved.

http://www.apress.com/apressopen/apressopen/9781430268390

good luck

Grumpy_Mike

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download this e-book for free and much of your problems seems to be solved.
Can't see how a book can compensate for basically a flawed hardware design.

Just what do you mean by this?

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