Circuit to Convert Binary to BCD

Discussion in 'Homework Help' started by Diamond, Feb 2, 2009.

  1. Diamond

    Thread Starter New Member

    Feb 2, 2009
    4
    0
    Hello Guys,

    I need to design a logic circuit that converts a four digit binary input to equivalent Binary Coded Decimal value. The circuit should have four input bits, but five output bit. For eg: input 1001 (decimal 9) the suggested output will be 0 1001 (the BCD value 09) for an input 1010 (decimal 10) the output should be 1 0000 (the BCD value 10).

    I need to create truth table and boolean expression for this.

    Please help out.

    Thanks
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Take a look at a BCD counter like a 74162. You shouldn't have any trouble with a truth table.
     
  3. Diamond

    Thread Starter New Member

    Feb 2, 2009
    4
    0
    Means!! I didnt get u :(
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    If you make a vertical column with all the binary values from 0000 to 1111, and another column with the corresponding BCD values, it will show you the circuit output for each binary input.
     
  5. Diamond

    Thread Starter New Member

    Feb 2, 2009
    4
    0
    Binary Values BCD Values (5 output)
    0000.......................00
    0001.......................01
    0010.......................02
    0011.......................03
    0100.......................04
    0101.......................05
    0110.......................06
    0111.......................07
    1000.......................08
    1001.......................09 (output in binary 0 1001)
    1010.......................10 (output in binary 1 0000)

    Ok This can be the truth table and this is the requirement. But how to develop circuit which which give me five output for four input bit with BCD values.

    I hope you have understood my requirement.
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Do you only have to go to 10d? 1111 is Fh, or 15d.

    Do you have any experience working with logic elements - AND gate, OR gates? You might notice that when the value is above 8 AND 2 OR 3 OR 4, etc, then BCD bit 4 sets.
     
  7. veritas

    Active Member

    Feb 7, 2008
    167
    0
    You will actually end up with 5 truth tables. Each table will correspond to one of your five output bits, and each will have four inputs.

    Go from there.
     
  8. Diamond

    Thread Starter New Member

    Feb 2, 2009
    4
    0
    See this is the actual question. I dont have practical experience of GATES except theory.

    Design a logic circuit that converts a four digit binary input to equivalent Binary Coded Decimal value. You need to first create the truth table (please note this circuit should have four input bits, but five output bits; for example, for an input 1001 (decimal 9) the suggested output will be 0 1001 (the BCD value 0 9); and for an input 1010 (decimal 10) the suggested output should be 1 0000 (the BCD value 1 0 )). After creating the truth table design the Boolean expressions for each of the five output bits. Draw the resulting circuit diagram using AND – OR – NOT gates.

    Please guide.
     
  9. Skeebopstop

    Active Member

    Jan 9, 2009
    358
    3
    your truth table is not that it is:

    inputs 1-4 : outputs 1-5
    0001 00001 (notice just same thing)
    0010 00010
    ....
    1010 10000
    1011 10001
    1100 10010
    1101 10011
    1110 10100
     
  10. Skeebopstop

    Active Member

    Jan 9, 2009
    358
    3
    an example segment of your logic would be

    (input1 and (input2 or input3)) gives output1
     
  11. patel

    New Member

    Apr 11, 2009
    1
    0
    Binary Values BCD Values (5 output)
    0000.......................00
    0001.......................01
    0010.......................02
    0011.......................03
    0100.......................04
    0101.......................05
    0110.......................06
    0111.......................07
    1000.......................08
    1001.......................09 (output in binary 0 1001)
    1010.......................10 (output in binary 1 0000)

    Ok This can be the truth table and this is the requirement. But how to develop circuit which which give me five output for four input bit with BCD values.

    I hope you have understood my requirement
     
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