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  1. #1
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    fpga oscilloscope

    Hi

    I 'm studying possibilities to make a digital oscilloscope for PC, with onboard RAM to memorize samples.

    I have several questions :
    => Wich bus is the easier to use (hard and driver for linux/windows) : PCI, USB or IEEE1394
    => I though about using many low speed ADC (cheapier) to reach sampling frequency I 'd like to use, is it a good way to do this.

    Which FPGA would be the most suitable for that project SpartanII, or APEX20k

    TOTO2001

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    usb oscilloscope project

    Try www.bitscope.com . They use PIC with CPLD.


    1 members found this post helpful.

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    •   Alt18th February 2003, 13:56

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    oscilloscope project

    Thank a lot for those usefull Links

    I think the second one is near of what i'd like to design.

    I'd rather use PC SDRAM memory to allow storage of samples, cheap solution with a FPGA.

    Toto2001



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    digital oscilloscope schematic

    hi toto
    look for "time interleaved sampling" or "interleaved sampling adc" on google

    theres an app note on this subject on the maxim homepage
    http://www.maxim-ic.com/appnotes.cfm/appnote_number/384

    but maybe this is not the best approach for hobby purposes
    Quote Originally Posted by Maxim
    Unfortunately, this approach is complex and entails extra cost, a lengthy calibration, and mathematical analysis.
    HTH
    dsp_



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    digital oscilloscope project

    Thank for the application note.

    It's almost what I was thinking about.

    Could a FPGA assume the clock for ADC sampling, I mean do you think the jitter on Clock signal would be acceptable for such a thing

    Thank for the anwers :)



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    jyetech oscilloscope

    This link could be useful :

    http://www.mccord.plus.com/FYP/final_report.htm

    (Implementation of a low-cost PC based quad channel real-time / storage oscilloscope).



    •   Alt19th February 2003, 01:36

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  8. #8
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    pc oscilloscope schematic

    In fact, I'not really looking for a low cost oscilloscope,

    It' rather a high speed oscilloscope at lower cost, based on FPGA in order to allows configurable sampling and filtering frequency, configurable sample width and number of samples. I'm particularly intrested in the possibility to make hardware digital processing before storage.

    I also plan to use PC memory to lower the cost of data storage.

    I don't which High speed pc bus (PCI, USB and firewire) is the easist to implement (with a chip or in fpga) and the cheapier.

    Here it is

    Toto2001



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    oscilloscope schematic

    Quote Originally Posted by toto2001
    In fact, I'not really looking for a low cost oscilloscope,

    It' rather a high speed oscilloscope at lower cost, based on FPGA in order to allows configurable sampling and filtering frequency, configurable sample width and number of samples. I'm particularly intrested in the possibility to make hardware digital processing before storage.

    I also plan to use PC memory to lower the cost of data storage.

    I don't which High speed pc bus (PCI, USB and firewire) is the easist to implement (with a chip or in fpga) and the cheapier.

    Here it is

    Toto2001
    For PCI, you usually buy a chip for the interface or a core and put into the FPGA. It will probably give you the fastest transfer of data between the scope portion of the FPGA and the PC. But doing a good high speed PCI can be difficult. Also, the design is not portable. (You need to move the entire PC around.)

    USB is good especially with USB 2.0. It is very good speed. You can purchase a USB chip that can come with all the driver development tool you need. The design is also portable. If you need to move the scope around to another lab, this is a better choice.

    I don't know too much about Firewire except used it on a few occassion. Mainly for Digital Video stuff. I will not recommended this interface for scope. I don't think it is ever used for instrumentation purpose.

    Anyway, just my 2 cents. Hope that help.

    Gunship



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    usb oscilloscope schematic

    The AD9283BRS-100 is a AD converter in the $6 range, free samples.

    8-Bit, 50 MSPS/80 MSPS/100 MSPS ADC



    •   Alt24th February 2003, 21:36

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    oscilloscope projects

    Thank for all those usefull advice.

    I had now a better view of what will be the project.

    In my firts mind, I was looking for PCI, but the mobility is an argument I didn't think about.

    The USB 2/1.1 seem a beter choice in the sense that it allow to be plug on a PC, a mac...
    It will just take a little longer to set the filters parameter and to back up all the data to the computer, but it may be easier to do too !!!

    If people are interested in taking part in it, they 're welcome

    TOTO2001



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    pc oscilloscope project

    http://alternatezone.com/electronics/dsoamk3.htm

    ISSUE 97
    August 1998
    Theme: DEBUGGING TECHNIQUES

    Task Manager—Almost Made 100, Ken Davidson, 2.
    Reader I/O, 6.
    New Product News, 8.
    Bitscope—A Mixed-Signal Capture Engine, by Norman Jackson, 12.
    http://www.circuitcellar.com/library/toc.asp



  13. #13
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    oscilloscope adc

    http://www.vitrum.cz/snail/bitscope.htm
    http://www.vitrum.cz/snail/products.htm#BITSCOPE

    or ftp.circuitcellar.com 21 Anonyymoue \ftp.circuitcellar.com\Circuit_Cellar\1988\Issue_5
    ftp.circuitcellar.com\Circuit_Cellar\1992\Issue_25
    ftp.circuitcellar.com\Circuit_Cellar\1998\Issue_97



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    oscilloscope fpga

    You could also have a look at the following link

    http://www.johann-glaser.at/projects/DSO/

    Goliath



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    oscilloscope front end

    I think that the bus of your chose should be mainly decided by your sampling rate. What is the maximum rate that you would like to sample? And you can go from there? Just bar in mind that your sampling rate should be at least 2.5 times more and also you should make sure that your sampling don't vary. You wouldn't want to be involved in a varying sampling system cause it is too complicated to handle so usually if you want to make sure that, then you might want to have some sort of a buffer mechanism between your PC and your board.

    Enjoy,
    RF_Router



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    dso schematic

    If you don't need deep memory, just generate two video rams
    to store pal or ntsc image and fill this memory with the graphic
    that you want to display. (scope graph) and generate standart
    video signal with this data. It is useful if you don't want to use
    a computer with your oscilloscope....



  17. #17
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    oscilloscope input stage

    Quote Originally Posted by Goliath
    You could also have a look at the following link

    http://www.johann-glaser.at/projects/DSO/

    Goliath
    this plan is best one !!!

    because it has a good solution in analog front-end!

    and i think the usb is a good choice, but is complex



  18. #18
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    pc oscilloscope circuit

    There is an error in this schematic: http://www.johann-glaser.at/projects...nSchematic.png

    IIC pull up resistors at SDA and SCL should be connected to 3.3V and not 5V as shown in the lower left corner of the schematic. Both AN2131
    and EEPROM is 3.3V types.



  19. #19
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    eoscope

    You could also have a look at the following link

    http://www.johann-glaser.at/projects/DSO/

    Goliath
    This link has not the sources for FPGA!?



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    firewire oscilloscope

    also check out www.fpga4fun.com, this guy has made a dso using a fpga, he's currently doing a tutorial on how he did it along with all the verilog code...

    A



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