Embedded controller for low cost STM

[Protsenko SI]

Our scientific lab wish to construct low cost and simple STM(Scanning Tunnelling Microscopy) for requirements of our laboratory. I now am in process of a select controller for our problem.

 I wish controller based on the blackfin or ARM or other (LabVIEW support is necessary)

We need use 1 Channel 16bit ADC and four channel 16bit DAC. Analog In/Out signal Will be feebly varying (up to 1000Hz).

Search has yielded only one suitable result (http://www.softdb.com/a-dsp_30_2_1.html), but it is former expensively for me. I ask for any help and advices.

Message Edited by Protsenko SI on 02-03-2009 03:56 PM

[Kevin_H]

Hi Protsenko,

You do have a couple options to choose from.

Blackfin with LabVIEW 

ARM with LabVIEW 

I believe the MCB2300 may be your best option.  

Let me know if I can answer any specific questions.

Regards,

Kevin H

[Albert.Geven]

That evaluation was done by us and is hampered by the fact that there is no good interrupt system available from LabVIEW

It has to be defined in c in the microcontroller and that is not really easy.

Furthermore during the evaluation you only have limited memory for programming.

Our conclusion, not yet good enough.

[Protsenko SI]

Controller MCB2300 offered by you has only 10-bit ADC/10-bit DAC. We need use 1 Channel 16bit ADC and four channel 16bit DAC.

How I can connect to MCB2300 16bit ADC/DAC? Where I can find them?

[Kevin_H]

Hi Protsenko,

I apologize for overlooking your resolution requirement.  That does make things a bit more tricky here.  It doesn't appear that any of the boards we offer meet that specification.  Most likely, you will have to find an Analog Devices ADC/DAC (through parametric search) and then interface them with one of our Blackfin devices. There should be three ways of doing this:

Option 1. Use a supported ADC. We have VIs for some ADCs in the Blackfin>>Driver>>Peripherals section. They are 1836, 1854, 1871, 7266. Look them up on Analog.com to see if they fit his need.

Option 2. If not, find an ADC from ADI, that they provide driver support for (source files). These files can be included in the VDSP project and you can make calls using the inline C node or Call Library function node. You can even make your own wrapper VIs if you are feeling awesome!

Option 3. Find a completely unsupported ADC that has a SPI interface and connect it to our BF board. Then use the SPI VIs to configure and read it as per its manual.

I hope this helps.  Let me know if I can clarify anything else for you.

Regards,

Kevin H

[Protsenko SI]

Thanks for the answer.

I like Option 1 more. But I have some questions.

24-bit ADC 1836, 1854, 1871 are audio ADC. In our case Analog In/Out signal Will be feebly varying (constant). Whether I can use audio ADC for feebly varying signals (up to 100Hz)? (We want a board with real 16 bit resolution and full-duplex capability (playback and recording at the same time).)

The analogue inputs and outputs would probably need to be modified, since they should be DC-coupled; sound cards typically use capacitive coupling?

Message Edited by Protsenko SI on 02-05-2009 02:22 PM

[Kevin_H]

For hardware specific questions, I would contact ADI.  Please let me know if you have any problems getting the info you need from them.

Let us know if we can help with any LabVIEW Embedded questions as well.

Regards,

Kevin H

[Jaidev]

Hi Protsenko SI,

It is actually fairly easy to select an ADC from Analog devices that has the exact specifications that you are looking for. And most ADCs today will support atleast one of the communication busses on the Blackfin: SPI, SPORT, Serial.

So all you do is use the Parametric Search on Analog.com and search for an ADC that meets your requirements: http://www.analog.com/dynamic/parametric/scResultsDisplay.asp?SearchType=PSS&ProductLine=ADC&la=en#

What makes this easier is

1. Most ADC manuals will tell you exactly how to interface with Microcontrollers/Microprocessors on SPI

2. Some ADCs also come mounted on SPI daughter boards that you can directly connect to our BF 537 EZKITs

Please let me know if you need more information.

Thank you,

Jaidev A

Message Edited by Jaidev on 02-06-2009 04:48 PM