Lab 7 - FL13 - ECE 198 JL - University of Illinois - Engineering Wiki

Lab 7 - FL13 - ECE 198 JL - University of Illinois - Engineering Wiki

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Lab 7 - FL13 Lab 7 assignment is due on Friday, October 11 in class. This lab is to be done in the EWS computer lab (DCL 440, DCL 520, etc.). Working on it remotely is not advisable as there are numerous technical difficulties in getting the software to work properly with remote access. Plan your time accordingly. Combinational logic design In this lab, you will begin to design a circuit that you will use to build a vending machine controller. You will design some combinational logic which will generate outputs that tell the vending machine whether to accept a coin that is inserted into the machine or dispense a product to the customer. You will need to use abstraction to solve this part of the problem, since we have not taught you how to keep track of how much money has been inserted. You must build your circuit as if you had a circuit that kept track of the how much money was previously inserted into the vending machine. This abstracted circuit will supply the signals S2, S1, and S0 to the circuit you are building in this lab. These three signals encode information that you will use to generate your output signals. The vending machine controller will accept only quarters (25 ¢) and dimes (10 ¢), will dispense a product when the customer inserts 35 ¢, and will accept only exact change totaling 35 ¢ (You need to be extra careful about which coins you accept, so that you can achieve exactly 35¢). Furthermore, the vending machine will also keep track of how much money has been inserted into the vending machine and what coin was just inserted. Use the specification below to construct truth tables and/or Karnaugh maps to derive simple SOP or POS Boolean expressions for the two output signals "Accept coin" (A) and "Paid in full (dispense Product)" (P). A = 1, when the coin that has just been inserted should be accepted. A = 0, when the coin that has just been inserted should be rejected. P = 1, when the product should be dispensed. P = 0, when the product should not be dispensed S2 S1 S0 Function/meaning 0 0 0 No money was previously inserted. A dime has just been inserted. 0 0 1 10 ¢ was previously inserted. A dime has just been inserted. 0 1 0 25 ¢ was previously inserted. A dime has just been inserted. 0 1 1 No money has been inserted yet. 1 0 0 No money was previously inserted. A quarter has just been inserted. 1 0 1 10 ¢ was previously inserted. A quarter has just been inserted. 1 1 0 25 ¢ was previously inserted. A quarter has just been inserted. 1 1 1 No money has been inserted yet. After you generate your Boolean expressions, implement, test, and debug your circuit in Mentor Graphics. Refer to Lab 5 for details how to use Mentor Graphics for building and simulation circuits. Next, use DeMorgan's law and other Boolean algebra properties to redesign your circuit so that it uses only NAND, NOR, and NOT gates. We recommend that you use only NAND gates or only NOR gates, but ultimately the decision about which gates to use is yours. Implement, test, and debug this circuit in Mentor Graphics. You will use it later in Lab 8.
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