DSP on PC/104 recommendations

I've been looking for PC/104 DSP options and am wondering if anyone has recommendations. I have a portable, stand alone data acquisition product that currently uses a custom system board and would like to replace it with a PC/104 system running linux. The system records pressure pulses (~ 1 pulse / second) in an noisy environment (pump noise, etc.). I am interested in adding a DSP card for filtering and freeing up the processor for user interface, networking, database, etc.

I've looked at cards from: Bittware, RTD Embedded, S&K Electronics, Signallogic, Arius, Mango DSP, Sheldon, SystemExcelerator and Sundance. Obviously, some of these are focused on communications or imaging and some blow the budget, although the RTD products are < $1K. I've also seen some non-PC/104 products that might work: dspstak from Danville Signal Processing or DSP Stamp from Cambridge Signal Processing. I haven't checked out PCI DSP cards - possibly they're more affordable and could be plugged into a PC/104plus system?

Anyone have any recommendations, pointers or war stories?

Thanks, Bill Turner

Reply to
pecosb
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Just curious: with such a slow speed of processing, why do you need a DSP? I thought any processor can handle 1 pulse/second computation without interruting its main task...

DS

Reply to
DigitalSignal

Just curious: with such a slow speed of processing, why do you need a DSP? I thought any processor can handle 1 pulse/second computation without interruting its main task...

DS

Reply to
DigitalSignal

We may be able to get away w/o a DSP - we're not using it now. But there is a lot of noise in the system and some of it can be very close in frequency to our signal of interest. I am thinking we may want to use the DSP to do some frequency domain filtering, edge detection on the pulse, etc. Plus with the new system we'll probably bump up our sampling rate so that we can still differentiate between the signal and noise as they get close together in frequency.

Thanks, Bill

Reply to
pecosb

The PC/104 bus is electrically ISA, not PCI, so a PCI board wouldn't help.

What sampling rates are you contemplating? If you aren't sampling too fast (you should be able to do 1kHz without any trouble at all, for heaven's sake!) you should be able to do it all in one processor -- particularly if you get a processor that has MMX capabilities. ADC cards for PC-104 are going to have deep buffers, so you may even be able to get away without using a real-time linux kernel.

--
Tim Wescott
Wescott Design Services
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Reply to
Tim Wescott

You are going to need really deep buffers if you intend to use some Geode based boards due to the SMM issue. Many "standard" PC features missing in the Geode, such as VGA text mode, are emulated by SMM, causing unpredictable delays. Transmeta processors may start to translate x86 to internal representation at some inconvenient time.

While these processors are convenient for ordinary processing, using them for any time-critical applications require a careful evaluation. If a large amount of real-time data needs to be captured, the input device should have big buffers.

Paul

Reply to
Paul Keinanen

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We will probably sample somewhere in the kHz range (1 - 5?). Initially we'll try it w/o the DSP since the processor will be able to handle it. But once we add on the other user stuff (database, remote data display, XML-RPC server, graphical reporting package) we might need the DSP to be sure we don't miss any samples. I was looking at the DSP now to head down the right hardware path. Some external cards interface best over the SPI bus; possibly this implies using processor board w/ SPI support built in?

Also, I was thinking of PC1-104 or PC/104 plus and plugging in a PCI board. This probably doesn't make much sense from a packaging standpoint.

Thanks for your help, Bill Turner

Reply to
pecosb

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