splitting 16 bit data into two 8 bit data

Discussion in 'The Projects Forum' started by kevin.khan, Jul 14, 2012.

  1. kevin.khan

    Thread Starter New Member

    Jul 9, 2012
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    0
    Hi there

    I have a chip that I am interfacing with a computer that transmits 8 bit data. However data being sent to the chip is 16 bits.

    I want to know how to create a hardware design (i.e. using ICs) to split the 16 bits into two 8 bits and transmit it to the chip which excepts 8 bits of data. Also I need to ensure that the MSB gets sent to the chip before the LSB.

    Any help would be greatly appreciated.
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    Give us the part numbers.
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,006
    3,232
    Load the 16-bits into a 16-bit register with tri-state outputs such as two CD4508 dual 4-bit latches or, if you don't need a latch, use three CD4503 Hex non-inverting tri-state buffers. Connect the upper 8 output bits in parallel with the lower 8 output bits. To send an 8 bit data packet just enable the tri-state outputs for either the upper or lower 8 bits as desired with the other 8 bits disabled.
     
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  4. WBahn

    Moderator

    Mar 31, 2012
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    Another way is to put two 8-bit registers in series. Then your 8-bit source outputs the 16-bit data MSB followed by LSB into the first register. Once the LSB is loaded, the full 16-bit data is available as the combed output of the two registers.

    Now, you will have to deal with synchronization so that the 16-bit device captures the data when you have the two 8-bit chuncks that make up the same piece of data available, as opposed to the LSB of the prior data value and the MSB of the next data value.
     
  5. WBahn

    Moderator

    Mar 31, 2012
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    Yet another approach is to simply connect the eight bits of the 8-bit port to either the upper or the lower 8-bits of the 16-bit port and put pull-down resistors on the other 8 bits.

    At that point it's a software problem. ;)
     
  6. crutschow

    Expert

    Mar 14, 2008
    13,006
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    I believe you are going in the wrong direction. ;) He needs to go from a 16-bit source to an 8-bit receiver.
     
  7. MrChips

    Moderator

    Oct 2, 2009
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    I wouldn't really know until the op posts both part numbers
     
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