Author Topic: generating high resolution square wave or a pulses  (Read 13198 times)

shimman

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generating high resolution square wave or a pulses
« on: August 07, 2010, 01:53:20 pm »
Hello,


i am trying to find an i/o available for a pc which i can use to generate high resolution square wave (10mhz or higher) or sub-microsecond pulses. the timing of output is very critical. i was wondering whether usb2.0/firewire data out can do the job i am looking for,

any suggestions where to start?

thanks,

shimman

shimman

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Re: generating high resolution square wave or a pulses
« Reply #1 on: August 07, 2010, 01:55:16 pm »
other than parallel port, are there any inexpensive i/o interfaces where i can get hardware interrupt generated? receiving time is important & like to have a sub-microsecond resolution.

thank you

Jan Axelson

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Re: generating high resolution square wave or a pulses
« Reply #2 on: August 07, 2010, 02:25:18 pm »
Program a microcontroller to generate the waveforms and use USB as needed to control the output. For example, the PC could send a command telling the microcontroller what frequency or waveform to generate.

Jan

shimman

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Re: generating high resolution square wave or a pulses
« Reply #3 on: August 08, 2010, 11:32:10 am »
Hi Jan!

thanks for your reply! i really enjoyed your parallel port complete.

the issue i am having is a synchronization. i need to generate a synchronization signal such as a pulse to a slave unit from a pc, but it seems that it is very difficult to generate precise timing signal from a pc. i was somewhat hopeful to use an usb, but it seems that clock tolerance is rather big 500ppm for instance. (i don't mind adding extra circuits)

any suggestions?


thank you

PS: any plan on writing ieee1394, pci-e books?
« Last Edit: August 08, 2010, 06:26:38 pm by shimman »

Jan Axelson

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Re: generating high resolution square wave or a pulses
« Reply #4 on: August 08, 2010, 06:55:42 pm »
Yes, Windows is not a real-time operating system and can't guarantee precise timing. If you can explain what you're trying to accomplish with the signals, maybe someone will have an idea.

No immediate plans to write about IEEE-1394 or PCI Express, but suggestions are always welcome.

Jan


shimman

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Re: generating high resolution square wave or a pulses
« Reply #5 on: August 08, 2010, 10:05:39 pm »
Thanks for your reply!

i am trying to do a latency measurement on linux and windows. what i like to do is to improve resolution of measurement over the software tools like tracers and performance profilers. the plan is to measure the latency over certain events which i plan on taking using a parallel port (parallel port complete!), but generating output from pc at the end of event processing in submicrosecond seems difficult without adding hardware assisted device.

at least, i like to avoid using something like 1588 ptp; i was also thinking of using pci-e, but usual pci-e development kit is bit too pricey for me at this point.


for your future book plans, i think it would be nice to see a data acquisition/control book using fpga & a network.

thanks,
shimman

Jan Axelson

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Re: generating high resolution square wave or a pulses
« Reply #6 on: August 13, 2010, 01:21:32 pm »
Yes, I think you will need an assist from external hardware.

Jan