DSP Robotics Support

I have different type of question.

We are building an analog instrument, and...
I'm looking for some cheap electronic kits, that:

1) convert analog signals to digital,
2) have output in USB standard, and
3) can act as a controllers (I guess midi?) for VSTi in DAWs.

In other words AD converter and USB midi controller - in one.
Can you help me to find something like that?

the best deals on the market
http://www.lividinstruments.com/hardwar ... hp#brainv2

http://www.doepfer.de/home_d.htm
http://ucapps.de/
http://www.elby-designs.com/
maybe you canfind some parts here too...

Thanks, Brain jr. looks promising.

Btw, another, somewhat related and unrelated hardware question.

Do you know where (which ones) to buy cheap A/D modules with USB output? I mean - multiple inputs (like the Brain jr. has), and connected to PC - board would be recognized as a standard (let say with 16 ins, am I correct? Can this be that way?) soundcard, with no drivers needed.

did you also watch the phigets which are supportet by flowstone? http://www.dsprobotics.com/flowstone-hardware.html ... or maybe one of this http://www.phidgets.com/products.php?category=0

Briefly, but still trying to familiarize with the concepts.
Anyway, two conditions for me:

a) must be cheap (around 50 USD)
b) must have usb connection to PC without need for drivers (class compilant)

That why I thought of audio related, yet cheap boards.
Inputs can be timed at 8kHz, which at 2x8 analog inputs gives 64kHz (8 or 16 bit, stereo mode) performance - it's enough for me.

I'm going to work with rather analog inputs, continuous sensors/measurement, no need for great "audo quality".

I see it like this:
dedicated sensors (separate issue) --> scaling to normalized analog inputs --> A/D & USB audio data in --> FS (or whatever else) app.

tester wrote:Inputs can be timed at 8kHz, which at 2x8 analog inputs gives 64kHz (8 or 16 bit, stereo mode)

let's calc: 8kHz * 2 * 8 = 128kHz
at 16 bit, this is a bitrate of at least 2 MBit/s ... that is FullSpeed USB 1 folks!

tester wrote:That why I thought of audio related, yet cheap boards.

And I don't get it, are you looking for A/D converter boards, or an USB soundcard? Don't mix them up, they work differently. Soundcards are AC coupled, A/D converters are DC coupled. This means, you can't measure low frequency or constant signals with a soundcard. A/D converters use (stabelised) voltage references to measure accurate values, the soundcard reference is completely up to its codec and doesn't need to be accurate or constant at all.

without the 8kHz rubbish, I would have said: get an AVR and an FT232 and build it up yourself... ~15 USD max.

MyCo - right now I'm too stupid to differentiate between such things

I saw in the past simple devices, that were using soundcard inputs for A/D conversion, that's why I thought about it at first. I have no knowledge on USB devices, all I can say is - when I plugin something that is "class compilant" (whatever that is; I understand it as a compatibility with standard windows driver for something), then it will work without additional drivers, for example as a soundcard (closest thing for me to understand); when I plugin strange kind usb device, like usb scanner, then it will ask for drivers or will not work without them.

I'm focused on cheap (!) bio-measurements, which require less than 8kHz sampling (guess max 1-2kHz, but soundcard-type A/D converters probably don't support that low kind of sampling rate), and not so great accuracy due to dynamics of these signals; it's not EEG I talk about, but things like skin conductivity or electric potentials - usually it's much about polarity or signifficant change or response or relationship, not about too accurate values. Reality of bio-sensors is, that they are cheap to do, but they are sold for crazy prices as if they were "something".

...get an AVR and an FT232 and build it up yourself.

That why I ask for links to some pre-made modules, so I can attach on one side scaled inputs, and on the other side - connect it to PC via USB, and have no worries about additional windows drivers. Just plug and play, in FS app select input, and go (can't the AD converter be connected to some USB bridge that acts like a soundcard? or I'm going into the wrong direction?). KISS so to speak.

tester wrote:That why I ask for links to some pre-made modules, so I can attach on one side scaled inputs, and on the other side - connect it to PC via USB, and have no worries about additional windows drivers. Just plug and play, in FS app select input, and go (can't the AD converter be connected to some USB bridge that acts like a soundcard? or I'm going into the wrong direction?). KISS so to speak.

I haven't seen a cheap A/D-module that interfaces as soundcard. Even the expensive ones done do that. Either they use their own drivers, or they use Serial. The FT232 that I mentioned is a classic USB<->Serial bridge, you'll find that on most of the cheap I/O Boards. Some more expensive one use a dedicated AT90, or even an ARM Controller that does USB and the processing at the same time.