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8 bit binary to decimal decoding

Discussion in 'General Electronics Chat' started by RAPIDRICK, May 3, 2008.

  1. RAPIDRICK

    RAPIDRICK New Member

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    I am aware that you can take a 4 bit binary number and decode it through, for example, a 7448 chip (BCD-to-seven-segment decoder) and display 0 through 9 on a single digit LED display. Is there a chip or a network of chips that will take an 8 bit binary number from, for example, an AD converter, and decode it to a 3 digit LED display to display 0 through 255? If anyone could help me on this, it would be greatly appreciated.
     
  2. Dean Huster

    Dean Huster Well-Known Member

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    At one time, you could get binary-to-BCD (74185A) and BCD-to-binary (74184) chips in TTL logic. If you can't find them, consider burning an EPROM with just such a look-up table. There are CMOS and TTL D/D chips that will output hexadecimal to 7-segment displays if hex will work for you (i.e., all you're wanting to do is have 7-segment displays vs. a string of LEDs, one per bit).

    Dean
     
  3. Mike - K8LH

    Mike - K8LH Well-Known Member

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    That would be a good application for a PIC (or other) microcontroller if you had the programming expertise.

    Mike
     

    Attached Files:

    Last edited: May 6, 2008
  4. dave

    Dave New Member

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  5. crutschow

    crutschow Well-Known Member Most Helpful Member

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    Another method uses counters. You need a binary up/down counter with jam inputs, a BCD up counter, a BCD to 7-segment LED readout decoder, and a clock (plus some timing logic). The BCD counter and BCD to 7-segment decoder can be combined in one unit if devices such as the CD4026B or CD4033B are used

    In operation the binary word is parallel transferred (jammed) to the binary up/down counter (configured to count down). The two counters then start with the same clock
    input, the binary counter counting down and the BCD counter counting up from zero. When the down counter reaches zero, the counting is stopped. The BCD counter now contains the value of the binary word in BCD format. This BCD signal drives the BCD to 7-segment LED
    drivers to display the output in decimal format.

    The number of chips for 8 bits would be one 8-bit counter (or two 4-bit counters), three decade BCD counters, and three BCD to 7-segment converters for the three digit readout, plus the timing logic circuits.

    The timing consists of a single pulse (such as generated by a Flip-Flop) to load the data into the binary counter and start the sequence, and logic to detect the zero count and stop the count.
     
  6. Pommie

    Pommie Well-Known Member Most Helpful Member

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    Mike,

    Shouldn't the transistors go to RB7, 6 & 5?

    Mike.
     
  7. RAPIDRICK

    RAPIDRICK New Member

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    8 bit binary to decimal

    Thanks to everyone for the replies. I may try looking for the 74185 chip or burning an eprom--that will be a new experience for me. Thanks again.

    Rick
     
  8. Boncuk

    Boncuk New Member

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    Looks great! Except for the PINK!
     
  9. kchriste

    kchriste New Member Forum Supporter

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    Last edited: May 5, 2008
  10. Mike - K8LH

    Mike - K8LH Well-Known Member

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    Yes. Good catch. I uploaded a corrected graphic.

    Mike
     

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