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Homework Help: Digital Electronics Homework Help

  1. Sep 16, 2014 #1
    I need help in creating a weighted timing controller that uses 4-bit DIP switch (Weight), 1-bit DIP switch (Fast/Slow operation) and etc. The question is shown below.

    Creating a Weighted Timing Controller:

    A simple microwave oven has two cooking modes: a "Slow cooking" mode that operates on low power and a "Fast cooking" mode that operates on high power. Cooking time for these cycles depends on the weight of items being cooked and is determined as follows.

    Fast cooking cycle: 2*Weight seconds
    Slow cooking cycle: 3*Weight seconds

    The system will not be functioned if the cooking cycle is more than 15. The weight is indicated by a 4-bit DIP switch. A 1-bit DIP switch is used to indicate the cooking mode (fast or slow). A push button is used as START button for starting the cooking process. A seven segment display and a LED are used to indicate the count in decimal format and only odd number count is showed during the cooking process. For example, if the count is 15, the LED is asserted and seven segment shows '5'. If the count is 9, only the seven segment display shows '9'.

    Implement the 4 bit weight DIP switch, 1 bit DIP switch for mode selection and cycle calculation.

    I try doing this using 4 JK flip flop and have a 4 input NAND gate (4 bit DIP switch) tied to the clear. But, I am not sure if this is the correct way and I do not know how to implement the 1-bit DIP switch for mode selection and cycle calculation (how do I make it 2*weight or 3*weight second)?

    Thank you for the help you render and if possible, please guide me on how to begin.

    Thanks in advance.
  2. jcsd
  3. Jun 14, 2017 #2
    In binary, multiplication can be accomplished by shifting the bits of items weight to the left once (weight times 2) then adding the original weight. If 1 pound is 0001 then to multiply by 3 perform the following
    0010 (0001 shifted left once) add original weight 0001 leads to 0011 in binary which when translated to decimal is 3 (3 pounds in your case). Classes in assembly language programming usually teach these concepts. Performing this task in hardware is not too difficult. Hope this helps
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