programmable gate array

Discussion in 'General Electronics Chat' started by PG1995, Oct 5, 2011.

  1. PG1995

    Thread Starter Active Member

    Apr 15, 2011
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    Hi

    I didn't know there existed programmable gate array. If I have a programmable chip, then can I configure it to behave, say, like the 74LS00 IC? What device is used to program the gate array? Is there something like USB SD card reader? Please help me with this query. Thanks.
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Well, yes you can create a quadruple nand gate, but definitely not in the same package and with the same pinout.
    FPGAs I know need some form of external memory, because the chip remembers nothing and needs to be programmed each time you power it up.
    On the contrary, CPLDs do remember their programming. Read here and here.
     
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  3. PG1995

    Thread Starter Active Member

    Apr 15, 2011
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    Thank you, Kubeek.

    How do you program them? Using some USB card reader type device?
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Like microcontrollers, each brand will have its own programming cable. Xilinx uses JTAG protocol, not sure about altera but I bet they will use something different.
     
  5. colinb

    Active Member

    Jun 15, 2011
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    CPLDs are programmed by proprietary devices. For instance, Altera CPLDs (such as the low cost MAX II CPLD) can be programmed by their ByteBlaster interfaces (other Altera devices).
     
  6. PG1995

    Thread Starter Active Member

    Apr 15, 2011
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    Thank you, Kubeek, Colin.

    Now I wonder why would someone buy regular IC such as 74LS00 instead of a programmable chip which can be configured to emulate behaviour of different logic chips? To me, programmable one is a many-in-one device and even if it costs slightly higher even then it's worth it. Thanks.
     
  7. crutschow

    Expert

    Mar 14, 2008
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    Programmable chips are often used to implement large, complex logic functions. They wouldn't be use to replace simple logic chips like the 74LS00 since they are significantly physically larger, need to be programmed, and cost much more than the simple chips.
     
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