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16  Using Arduino / Audio / Re: i want to record audio in real time to matlab just record by any program on: September 24, 2013, 02:20:35 pm
you can use an arduino to capture sound, but matlab has a function which can capture straight from your soundcard, so you that would probably be a better route.  there are shields that can give you high quality audio from your arduino, but these are more work/more money that just using the computer. but, they might be good for a portable application.
17  Using Arduino / Audio / Re: Audio Sampling Rate on: September 11, 2013, 01:23:23 pm
200kHz is the reccomended fastest ADC clock speed, not the ADC sample rate.  the ADC needs at least 13 clocks to take a sample, so its more like 15ksps.  but, you can go faster with slight bit depth/resolution tradeoffs.  these are all documented here:

http://www.openmusiclabs.com/learning/digital/atmega-adc/
http://www.openmusiclabs.com/learning/digital/atmega-adc/in-depth/

i find the 38ksps rate to be the sweet spot for best audio performance.
18  Using Arduino / Project Guidance / Re: Expanding the Repatcher on: August 14, 2013, 06:58:57 am
they do make shift registers that can switch between parallel to serial, and serial to parallel, but i dont think that helps in this case.  you need one shift register to hold a voltage, while the other shift register clocks the data in.
19  Using Arduino / Project Guidance / Re: Expanding the Repatcher on: August 13, 2013, 04:04:20 pm
you will want to change the code so the connection information is stored across a number of bytes.  so rather than put them all in a long, just do 4 bytes.  you then setup Pure Data to repack them, or just use them as they come in.
20  Using Arduino / Programming Questions / Re: Improving FHT resolution on: August 12, 2013, 11:30:56 pm
to sample slower, you can either setup the ADC to sample on a slower interrupt, or just use analogRead().  the latter is probably easier to get started with.  you can call analogRead(), and then put a delay in for the right amount of time.  be sure to comment out all the ADC setup code before using analogRead().
21  Using Arduino / Project Guidance / Re: Expanding the Repatcher on: August 12, 2013, 04:45:07 pm
this is possible, and shift registers are probably the way to go.  the only thing to watch out for, is that it will end up needing a lot of diodes.  each output needs a diode.  so if you make a 16 x 16 patch bay (and want to have 16 outs per row) you will need 256 diodes  the speed will be fine as well, it doesnt take much processing to scan the array.  look around for a project with shift registers and see what they used for code.
22  Using Arduino / Programming Questions / Re: Uncooperative code: FHT vs Display on: August 11, 2013, 09:23:22 pm
get rid of the lines:

TIMSK0 = 0;
cli();
sei();

and see if that helps.
23  Using Arduino / Audio / Re: Convert analog input from mic to decibels on: August 11, 2013, 04:05:24 pm
yes, this is possible, but you will need to calibrate your microphone in some way (at least if you want the decibels for comparison to other data).  you should look around and see if anyone has written an RMS function for arduino.  it wouldnt bee too hard to implement elsewise.  then its just 20*log(value).  i have a fast log(sqrt()) i can dig up if necessary.
24  Using Arduino / Audio / Re: Storing data in an audio channel on: August 10, 2013, 02:58:51 pm
i made a mod/demod for transmitting data over the audio channel in skype (which uses lossy compression).  but, i found that it would drop continuous tones more often than varying tones.  so making sure the signal is chaging a lot might help.  dont send lots of FF or 00.
25  Using Arduino / Audio / Re: Strange behavior with power supply vs. computer USB power on: August 09, 2013, 03:25:56 am
when you plug your arduino into the USB on your computer, you are doing 2 things: 1. giving it 5V power, 2. connecting it to a device that it can talk to.  your code is most likely trying to talk to the computer, and when there is no computer connected, it fails, and the program hangs.
26  Using Arduino / Audio / Re: Strange behavior with power supply vs. computer USB power on: August 07, 2013, 11:14:23 pm
sounds like a code thing.  can you post your code, and which versions of libraries you might be using.
27  Using Arduino / Audio / Re: Strange behavior with power supply vs. computer USB power on: August 06, 2013, 08:37:37 pm
do you have something that supplies 5v over a usb cable?  like a small charger?  if that worked, it would rule out the powersupply question.  its more like a code thing, like hanging on a serial.available() or something
28  Using Arduino / Audio / Re: Storing data in an audio channel on: August 05, 2013, 06:56:32 pm
the data rate you will get will depend upon the lock time of the PLL (XR2211).  this is typically set the by the lowpass filter time constant on the output filter, which is usually pretty slow.  a better estimate would probably be closer to 250bps.  always makes me impressed with 56kbps telephone modems.  also, why is the audio bandwidth of the recorder so low?  im assuming the 3kHz is the max frequency it can accept, and not the sampling rate, which means you can go higher than 1.5kHz (all the way to 3kHz).
29  Using Arduino / Audio / Re: Storing data in an audio channel on: August 05, 2013, 02:08:47 pm
the XR2206 is an awesome chip.  but you can probably just generate the tones with the tone() library.  what is your plan for decoding?  if you need a higher data rate you might be able to send a series of different tones, each representing a different value.
30  Using Arduino / Microcontrollers / Re: bug in optiboot bootloader on: August 03, 2013, 01:54:28 pm

Couldn't you put a dummy section at the end of the linked image to ensure that this never happened?
Yeah, it would require a tweak to the Arduino team controlled code but it's a one time thing.

another nice thing about this method, is that people could just update their arduino ide, rather than burning a new bootloader.
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