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Unformatted text preview: CMPT 250 Final Exam April 15, 2002 You have 180 minutes to complete this exam. Answer all questions in an answer booklet. Do not hand in your question sheet. There is a total of 75 points on this exam; points for each question are indicated. Read through the entire exam before you begin. There are 8 pages ( not counting this page); make sure you have them all. No books, calculators or any other aids are allowed. Where appropriate, clarity and simplicity of your solutions count, as well as correctness. All Figures are at the back of the exam. CMPT 250 Final Exam, Apr. 15, 2002 1. [10 points] Suppose we want to create a control circuit to control a garage door opener. The circuit will have the following control inputs. These signals will be 1 when the given condition is true and 0 when it is false: b up : A button has been pushed to raise the door. b down : A button has been pushed to lower the door. sensor : A sensor has detected something under the doorif its currently going down, it should go back up. end : The door is all the way up or downthe door should stop. The circuit will have two output signals: motor up : When set, the motor will raise the door. motor down : When set, the motor will lower the door. These signals should never both be set to one; it will burn out the motor. When both are zero, the door will be held in its current position. Draw an ASM diagram that describes this circuit. 2. [10 points] We want to create a VHDL entity to implement this combinatorial circuit: Y X A B C Figure 1 contains a VHDL implementation of an AND gate; you can use it for reference....
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- Spring '97