Updating legacy system

? How many channels of 16 bit 500KHz. Just one? For one channel that 8Ms/s.

? How long do you have to sample for?

? Who made the selection for the laptop. Bad decision.

National Instruments have several options, but none faster than

200ksamples/second NI DAQCard-6036E (for PCMCIA) 200 kS/s, 16-Bit, 16 Analog Input Multifunction DAQ

" snipped-for-privacy@ev1.net" wrote in news:416fd0d9.3c8.41@news2:

I googled for USB based data acquisition and several companies showed up. Not sure if they have the bandwidth you require.

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- Mark ->
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You'll never get 500k samples out of USB1. Why don't they buy a new laptop?

Sack the people who gave you those limitations. Ethernet 100Base-T should be fast enough I suppose, just give them a giant industrial PC box with the original ISA card in it, and a PCI network card, and run the whole thing with DOS or ECOS or whatever.

Paul Burke

[1] Say this: "Windows 2000, Real-Time, Reasonable Cost. Pick any two." Arm yourself with lots of data on the (lack of) real-time capabilities of Windows (yes there are things like RTX. They will cost you). [2] Tell them to tell you what they want not how to do it. "Laptop" is telling you how to do it. "smaller that X size" or uses "less that X power" is telling you what they want. Then convert it to a PC104 system running DOS. [3] If they won't listen to you, get a consultant to tell them.

Windows 2000 has nondeterministic scheduling. The Windows 2000 kernel periodically disables interrupts for indeterminate periods of time. Drivers can disable interrupts for extended periods; the ATAPI driver is well-known for doing this. Your laptop is likely to have a SMI (System Management Interrupt), which is a non-maskable interrupt that preempts and disables all other interrupts and puts the processor int System Management Mode at a frequency and for a duration that is different for every manufacturer and often different between revisions of the same laptop.

DMA does not involve the processor whatsoever, so the OS is almost irrelevant until it's time to *do something* with the data.

I think you have had some silly restrictions placed on you though, but what's new.

[4] If they won't listen to the consultant, tell them that the only elegant way to do it is to interface to the expansion port on the laptop (that's the big ugly connector on the back that plugs into the docking station). This will require signing an NDA with the laptop manufacturer in order to get the interface spec for the connector. If the laptop ever breaks, the entire interface will need to be re-designed to work with the new laptop from a different vendor.

If that still doesn't work, then you might have one other option (although not too elegant) You could try interfacing to the IDE port. The 50-pin connector pinout and protocol is well documented, and the transfer rate should be high enough even in PIO4 mode. This is assuming that (1) the IDE controller in the laptop will recognize a slave device other than its own CDROM which you would probably need to disconnect (2) you can implement enough of the ATAPI spec in your device so that Windows recognizes it as a standard device or you write your own Windows driver and finally (3) you can live with a fragile little ribbon cable sticking out of the bottom of the laptop or the laptop has a removable CDROM and you can stick your device into the CDROM bay.

That being said, personally I would abandon the whole laptop idea as it seems to be a lot more trouble than its worth.

--Tom.

" snipped-for-privacy@ev1.net" skrev i meddelandet news:416fd0d9.3c8.41@news2...

Assuming the the laptop is new enough to have cardbus, you can get a USB 2.0 High speed PCCARD and insert in your laptop. There are circuits which includes CPUs and Card Bus Salve interfaces, but you should maybe consider an FPGA and have a Cardbus interface implemented in that. You have forgotten to mention Ethernet, but maybe the delays are killing this option. An ARM9 like the AT91RM9200 can connect to the 16 bit ADC and process quite a lot of information and should probably have the speed to handle low level data, and then you can process and display on the laptop.

Do you want to process a continous stream of data, or just read data for a short time? The "Realtime" requirement says no, but I just want to clarify- You could buffer the data and then send it at a slower rate.

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Best Regards
Ulf at atmel dot com
These comments are intended to be my own opinion and they
may, or may not be shared by my employer, Atmel Sweden.