Newbie Here

RayNM

I have been reading up about the basic stamp and now I wonder which would be the best for my application.
I want to interface it to the output of a differential integrator and try to get some useful info on a low level signal. Actually this is part of a PI metal detector and I want to be able to both read the data and control the various amplifier and timing stages of the detector. So if someone could give me a clue on which of the stamps I should purchase it would really help.
Thanks
Ray-nm

Mike Green

It depends on a lot of information that you haven't given yet. In particular, what kind of information do you actually want to process. Is it already in digital form? If not, what's the voltage range, accuracy desired, sample rate, etc.? What means do you have to control the amplifier and timing stages of the detector? Do you need digital signals? What format? Are they analog? What's the voltage range, accuracy desired, update rate? Assuming this is all analog, you will need analog-to-digital converters and digital-to-analog converters. In very simple circumstances, the Stamps can do this, but very slowly and with limited accuracy. On general principles, I'd suggest a Stamp in the BS2p series. They have some extra capabilities (statements) that the other Stamps do not.

RayNM

Sorry I reread my post and you are right not enough info. The signals will be analog so I will need an a/d converter. I will be pulsing the coil from 10 to 75 usec with a freq of 900hz to about 2300 hertz. What I am doing is sampling at about 10 usec after the pulse. I may have to read the sample at about every 4th pulse since some of the a/d converters cant convert that fast. Any way it is a learning experience for me. Wanted to do it fairly cheaply while I learn how it all works. besides I think it will be fun.
I will look at the BS2p series unless my answer clarifies this a little more
Thanks

Mike Green

None of the Stamps are fast enough to handle the timing of the signal sampling. They can generate fairly accurate short pulses in the frequency range you're using, but only execute about one instruction every 50us at best (for the BS2px). If you can do the timing for a sample and hold circuit external to the Stamp, maybe triggered off the coil pulse trailing edge, then you should be all right. The ADC0831 can convert a sample in 32us and interfaces easily to the Stamps (there are plenty of app notes on Parallax's website). There's also a 4 channel version (ADC0834) that Parallax stocks.

RayNM

Thanks for the info I will look at the adc0834 since I might like to sample more than one signal.

Mike Green

Do have a look at the Propeller which is more complex, newer (thus not as much "ready-to-use" examples and support), much faster and more sophisticated. It can do the A/D and D/A conversions itself with only a few passive components (although there are advantages in using external converters for this) and do all the timing (with a resolution on the order of 12ns). You can use a keyboard and video monitor (with text and graphics) for controlling and monitoring the operation of the system.

RayNM

I will

cocokiwi

RayNM said...
I have been reading up about the basic stamp and now I wonder which would be the best for my application.
I want to interface it to the output of a differential integrator and try to get some useful info on a low level signal. Actually this is part of a PI metal detector and I want to be able to both read the data and control the various amplifier and timing stages of the detector. So if someone could give me a clue on which of the stamps I should purchase it would really help.
Thanks
Ray-nm

· Have a look at the NEW MoBo stamp-pe #28300

· Has some real nice functions!

· Has TWO Coproccessors to crunch PWM and will read A/D to 10bit,and you can hang a serial LCD on it!

·I have one! NICE! might meat your needs. i included the main PDF files..enjoy.


Cheers Dennis

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http://people.delphiforums.com/cocokiwi/Image/picture.jpg

RayNM

Thanks I will take a look at it. as nothing is set in stone yet.
Ray