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High speed ADC with USB interface

Discussion in 'Hobby Electronics' started by Guest, Jan 23, 2005.

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  1. Guest

    Guest Guest

    I'm looking for 12-16bit ADC with 4MHz samplingrate capable of storing 4K
    samples, with USB interface to transfer data to a PC.

    Any recommendation ?
     
  2. I doubt that you will find this ADC/USB/Storage on a single chip.
    With 4 Mhz sample rate and 12 ´bit resolution
    you need 48 MHz operation for a serial interface
    so it is likely you need a parallell interface.

    I assume you store the samples first and then send it over USB.
    Then you need 8 kB of storage for the samples.
    Is it acceptable to use a UART at 115 kbps which connects to a USB-Serial
    bridge?
    You can transfer 4kW in about 1 second?

    You would be looking for a micro with
    * DMA capability for 4 Mtransfer/s
    * 16 bit Bus
    * 8 kB extra SRAM (16 kB min)
    * USB interface, or connection to an external UART-USB bridge
    * External ADC

    The AT94K05 FPSLIC has enough RAM and can directly interface to
    the ADC using the FPGA area, but lacks the USB.
     
  3. Richard Webb

    Richard Webb Guest

    Analog Devices do some evaluation boards for some of their ADCs which you
    can interface to their 'USB FIFO' board, might be suitable, although I think
    the ADCs in question are far faster than 4MSPS.
     
  4. Mike

    Mike Guest


    WoW now that would be something for sure - geeeesh as I ponder
    the frailties of using a 60KVA 3-phase UPS as a paperweight !
     
  5. Guest

    Guest Guest

    My appologies.!.. Altough I said ADC, what actually I mean an ADC board, not
    necessary single chip.

    My corrected question is;

    I'm looking for 12-16bit ADC Board with 4MHz sampling rate capable of
    storing 4K samples, with USB interface to transfer data to a PC.

     
  6. A 12-16 bit ADC with 4 Mhz sampling rate requires a minimum throughput of 48
    Mb/s, and a maximum of 64 Mb/s. This means you must have a Hi-Speed USB 2.0
    IC, which is capable of the theoretical maximum of 480 Mb/s.

    One candidate is SMSC's GT3200. It has a 16-bit parallel interface, thus it
    is possible to interface it with any modern microprocessor. For the ADC
    unit, I'd look at Analog Device's ADC selection matrix. They have at least a
    16-bit 65 MSPS (Million samples per second) device and a 16-bit 3 MSPS
    device. If your sampling rate of 4 Mhz is absolute, the 65 MSPS is the
    nearest suitable 16-bit one. The interface is parallel, thus it would be
    directly compatible with the GT3200.

    If a lower sampling accuracy is enough, AD also offers a 12-bit and 14-bit
    10 MSPS devices, both with parallel interface. The upper 4(2) bits of the
    USB unit could be used for signalling, if necessary.

    I have only experience with the AD's ADC units, and they've been positive
    experiences. Dunno about the GT3200, but you could try checking them out.

    -Antti Keskinen
     
  7. If the board needs/has a sample buffer, then there is no need for the high
    speed.
    You get 4k samples and then upload it over 12 mbps USB at leasure.


    /Ulf
     
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