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to show 0 to 99 to 7 segment display

Discussion in 'Electronic Design' started by [email protected], Feb 15, 2007.

  1. Guest

    How to show 8 bit binary number to 7 segment bcd display ????
     
  2. Dave Pollum

    Dave Pollum Guest


    There are lots of BCD to 7-segment decoder/driver chips. 7447 and
    CD4511 come to mind. Search Digikey and Mouser for part numbers.
    HTH
    -Dave Pollum
     
  3. TIL311, one of my favorite parts from the days when I did all designs
    in TTL. It includes latch, decoder, drivers, and LEDS, and displays 0-
    F from 4-bit input and has right and left decimal points as well. Now
    made by Taos and available from Mouser.
     
  4. Dave Pollum

    Dave Pollum Guest

    A TIL-311 looks really great, but it's very expensive. Mouser's price
    on the TIL311 is $26.82 (qty 1-9) and $23.47 (qty 10-24). Ouch!
    -Dave Pollum
     
  5. They were equivalently expensive back when we used them in the 80's
    (about $7 as I recall). But since they included the leds, current
    limit resistors, latch and decoder in the space of a DIP package, they
    were a bargain in some applications.
     
  6. An eight bit binary number ranges from 0 to 255 (decimal) so you will need
    three 7-segment diplays to show the eight bits number in BCD.

    There are some solutions but as you didn't give any constraints it's hard to
    tell which one will suit you.

    If you need one off and space is not a problem, a quick and dirty solution
    is programming three old EPROMs like the infamous 2764. As maybe the EPROMs
    cannot provide enough power to drive the LEDs of the display you may have to
    put drivers or transistors between the EPROMs and the displays.

    Likewise you can use GALs although you may run into a fitting problem.

    You can go for a two stage solution. Use EPROMs or GALs to convert from
    binary to BCD and standard BCD to 7-segment decoders/drivers, like the
    CD4511, to convert BCD to display.

    You can program a PIC16F870 or similar for the conversion and multiplexing
    of the three displays.

    The biggest solution I can think about is a PC with an EPP or other
    bidirectional parallel port. Read the eight bits from the port and display
    the number on the screen. An old DOS machine and one line in GWBASIC will do
    the trick.

    (You can use a mainframe as well but I expect real space and power problems
    in that case.)

    petrus bitbyter
     
  7. Rich Grise

    Rich Grise Guest

    And they're hex displays, i.e. 1 2 3 4 5 6 7 8 9 a b c d e f.

    The OP asked for BCD.

    I've already given him (or her or it) the answer - OP needs some way
    to get BCD out of binary, and OP'll need 3 digits of display, from
    000 to 255.

    But posting the same message seventeen times in two days shows the
    guy really has no clue in the first place. What's up with these google
    groupies? Do they think they can just post their homework questions
    and have answers magically appear on their desk?

    Feh.
    Rich
     
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