USB to DIO

Discussion in 'The Projects Forum' started by jismagic, Sep 25, 2013.

  1. jismagic

    Thread Starter Member

    Sep 7, 2013
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    Hello guys

    usb to digital io. what will be the cheapest available in the market?

    Requirment : 48-96 IOs
    Budget : max 150 usd.

    thanks,
    jis
     
  2. ScottWang

    Moderator

    Aug 23, 2012
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  3. jismagic

    Thread Starter Member

    Sep 7, 2013
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    is there any way i can control my output to 3 states of digital io
    - high state
    - lo state
    - open state

    most of the ics i looked cannot be controlled individually for open state or high impedance state.
     
  4. ScottWang

    Moderator

    Aug 23, 2012
    4,853
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    CD4051,74HC244,74hc574 they are all 3-states, and they are using to input and output.

    You can check their functions - http://www.datasheetcatalog.com/.
     
  5. jismagic

    Thread Starter Member

    Sep 7, 2013
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    Tristate outputs cannot be individually set.. means either all outputs are in tristate or none..
    .. is what i understand.

    if i am wrong, please correct me.

    let me know if there is any device available which can do 3 states.

    thanks,
    jis
     
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    I think some of the "port expander" ICs can do tri-state with individual control of each pin.

    Microchip (that makes PICs) have a port expander IC range. They are I2C or SPI driven, so you might be able to get a single USB-SPI module, then use it to drive a heap of port expander chips. :)
     
  7. ScottWang

    Moderator

    Aug 23, 2012
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    Control bit by bit is too expensive, but you can send the data to the inputs of 74HC574, and using /OE to control that you want to output or in tri-states, and send the clock to cp to transfer all datas to the output side, so you can change each bit you want, and the 74HC244 is input from external, you also can do the same thing that you can input for each bit, you may have some mistake for the conception or I can't catch your thought.
     
  8. jismagic

    Thread Starter Member

    Sep 7, 2013
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    three ideas im trying to implement

    1. i have 8 digital ios to create 32 digital ios- simply due to 32 digital ios are costlier than 8 dios

    2. i have to have 3 states , hight state, low state and open state.

    3. Im trying to control this from my windows computer.
     
  9. ScottWang

    Moderator

    Aug 23, 2012
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    Why you need the open state, for what?
    Individual tris-state for input/output - 74HC125,CD4066,74HC4066
    Tri-state output flip flop : 74HC74 + 74HC125.
     
  10. jismagic

    Thread Starter Member

    Sep 7, 2013
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    I am a kind of doing a test box which will be connected to a product while test is happening. Now i dont want testbox to do any influence on product function.
    I want to stay open initially and then go to ground or high when required for the input pins..
     
  11. MaxHeadRoom

    Expert

    Jul 18, 2013
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    What I did when confronted with a similar problem was to decode 8 bit binary for 255 possible outputs.
    In my case I used an off the shelf PLC for the decoding and all the outputs were conditioned already, so no extra electronics, If you need the three states then you could also do this with discrete IC's or a PicMicro.
    Max.
     
  12. jismagic

    Thread Starter Member

    Sep 7, 2013
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    Whats the off the shelf PLC you used?

    thank you too..
     
  13. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Mitsubishi FX series.
    Max.
     
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