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Binary to decimal: how to send 8 bits to 2 displays or ...?

Discussion in 'Misc Electronics' started by Tari, Aug 25, 2003.

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  1. Tari

    Tari Guest

    Hello!

    I'm working on a project that requires to display binary words (8
    bits) on a 7-segment display. It is the purpose to show those words
    decimally. Anyone knows of a device that can convert an 8 bit word
    into the correspondent decimal numbers (0, 1, 2, ..., 9, 10, ..., 64
    (that's where I have to set a reset))?
    I was thinking of using 2 displays, but I don't know how to deal with
    it. Or does there exists a 7-segment-display that exists of 2 parts,
    so that you automatically can show numbers like 20 etc. ?

    I hope some one can help me.
    Thanks in advance!

    Greetings
    Tari
     
  2. Tari
    It might be easiest to represent the 8 bit word as a 2 digit Hexadecimal
    number. If you *must* represent it as a decimal, it will take three digits
    (000-255) and some significant logic to convert from binary to decimal. The
    simplest way I can think of to do this would be to use a microcontroller
    which could also drive the display. Is this a possibility?

    Richard
     
  3. Fred Abse

    Fred Abse Guest

    Quick and dirty method for a one-off:

    State table in 16-bit EPROM, or two 8-bit EPROMS. Drive the address lines
    with the input byte and use the data lines (buffered) to drive two
    7-segment displays.

    Breadboard it in an hour. Write the state table in ten minutes.

    Use those 4716s you never could bring yourself to throw away :)

    Otherwise you could use a couple of 74*185 binary to BCD converters,
    then two 74*49 BDC to 7-segment decoder/drivers driving two 7-segment
    displays.

    There's lots of other ways of doing it, but since it looks like a school
    project, I'll leave you to find those out yourself.
     
  4. Set a reset? Sounds like you might be coming from a counter.
    If so don't use a binary counter, use a 2-digit BCD counter.
    Each digit then goes directly to a BCD-7segment display/driver.

    If it has to be a binary input then the old microprocesser
    logic would be..... Split the binary D7-D0 into two nibbles,
    D7-D4 is hi-nib and D3-D0 is lo-nib. Look at lo-nib.

    If lo-nib is less than 9, then the two BCD output digits are
    simply hi-nib and lo-nib. If lo-nib is greater than 9, then
    the two BCD output digits are (hi-nib + 1) and (lo-nib + 6).

    This could be done in hardware (1x 4-bit magnitude comparator,
    and 2x 4-bit adders), or in software in a microprocessor.
    A little 18-pin PIC has just about enough i/o to do it.
     
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