74ls96 function error in proteus

Discussion in 'Homework Help' started by cl4y, Mar 17, 2016.

  1. cl4y

    Thread Starter New Member

    Mar 17, 2016
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    Hi, I'm having a problem about 74ls96 5-bit shift registers, the functions seems wrong.
    When I try to make the clear/preset to 00 and 10 work fines
    but when clear/preset is 01 the function should allow the q point to follow their respective inputs to a 1 or 0 and it's not happening also when the clear/preset is 11 it allows the q point to follow their respective inputs from a 0 to a 1 but not from a 1 to 0,
    please help thanks.
    sorry for the grammar.
     
  2. dl324

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    Mar 30, 2015
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    Welcome to AAC!
    Clear is LOW active and must be HIGH before preset is enabled.
    Preset will only set a bit to 1. The expected use is to clear the registers before using preset.
     
    Last edited: Mar 17, 2016
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  3. cl4y

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    Mar 17, 2016
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    Thank you :)
     
  4. cl4y

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    Mar 17, 2016
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    Sir, another question do you know how can i make the 7496 shift to the left?
     
  5. dl324

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    It can only shift right.
     
  6. cl4y

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    Mar 17, 2016
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    Sir, how can i prove to my professor that it can't shift to the left ? Cause he asked my classmates that if he can make it shift to the left he'll give them a failing grade. It is possible to make it shift left by adding some gates, and still I can insert 1 or 0 when shifting ? Thank you.
     
  7. dl324

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    Since this is homework, we don't do the work for you. Look at the datasheet for 74LS95 for some clues.
     
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  8. cl4y

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    Mar 17, 2016
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    Sir, the 74LS96 will only shift if the Clear is 1 and Preset is 0, am I right? Can I have a last clue sir ? I don't know what to do about the clear and preset. When Clear is 1 and Preset is 0 it disable the changes from the Q points. How can I make it shift to the left, if I can't make changes in the inputs like the 74ls95, please help, this would be the last I'll ask about this. Thank you in advance..
     
  9. dl324

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    Below is the function table for the shift register. I've circled the conditions required to shift (right).
    upload_2016-3-20_7-29-52.png
    What year are you in your studies? Does the LS96 allow you to "preset" a 0?
     
  10. cl4y

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    Mar 17, 2016
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    I'm a 3rd year student sir. Yes. Thank you sir for all the help.
     
  11. dl324

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    If the LS96 was capable of left shifting, how would you implement it? More specifically, how could you parallel load a zero?

    If your "yes" was to my query regarding being able to "preset" a zero, read the datasheet; looking closely at the logic diagram.

    Did your professor bound the amount of logic you could or should use to implement left shift?
     
  12. cl4y

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    Mar 17, 2016
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    Last edited: Mar 20, 2016
  13. dl324

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    Can you "parallel load" a zero on the LS96?
     
  14. cl4y

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    Mar 17, 2016
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    By having this config sir ?

    [​IMG]
     
  15. dl324

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    What will happen to all of the bits that were 1's?
     
  16. cl4y

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    Mar 17, 2016
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    Will depend on the preset? If the preset is 0 the 1's will turn to 0, and if the preset is 1 the 1's will stay 1? am i correct sir ?
     
  17. dl324

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    If you have a combination of 1's and 0's that you want to parallel load, how can you do it with the LS96 functionality? You can clear all bits to 0 or you can set all bits to 1; how can you handle a combination of 1's and 0's?
     
  18. cl4y

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    Mar 17, 2016
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    By Having the Clear set to L and the Preset Enable to H sir, I can have the Q points to have a combination of 1's and 0's
     
  19. dl324

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    If you had 00101 in the shift register, how would you wire it to shift left? If you clear the shift register so you can "load" 0's, you lose the 1's.

    Since this is an academic problem contrived by a professor divorced from reality, it can probably be done. In the real world, you would just select a more appropriate device.

    BTW, I can't read part numbers from either of the schematics you posted. From what I could read, you don't have the parallel inputs of the shift register connected. To get this seven you mentioned, are you shifting serially?

    Could you use the upload option on the form instead of posting on some hosting site? It serves up "advertisements" that are not Wife-friendly.
     
  20. cl4y

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    Mar 17, 2016
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