Spring_05_Project - The controller does not give any...

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Spring 2005 COCO Project Spring 2005 COCO Project Description and Specifications Description and Specifications 1. Description of the Vending Machine The vending machine delivers a package of goodies after it has received 25¢ or more in coins. The machine has a single coin slot that accepts only nickels, dimes and quarters, one at a time – no pennies. The block diagram of the controller is shown here. A Coin Sensor device indicates to the Controller whether a nickel, dime or quarter has been inserted into the coin slot. A Coin Dispenser device returns any coins held; otherwise, the coins go into a Coin Box. This is shown at the bottom of the page. 2. Specifications for the Vending Machine Controller Q or D or N is true for one clock period when a Q or D or N is inserted into the coin slot. A package of goodies is dispensed only once 25¢ or more has been deposited.
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Unformatted text preview: The controller does not give any change. For example, if the coins inserted are N, D, N, D, totaling 30, the controller does not return the extra 5. The controller does apply the extra amount deposited (5 in the example) as a credit to the next user. Only 20 needs to be inserted to obtain the next package of goodies. The input Coin_return is active for one clock period. This activates the Return_coins output. The Return_coins output is asserted only when there is less than 25 credit in the machine. (The Coin Dispener device returns any coins that have been deposited since the last time Dispense_goodies was asserted.) Q D N Coin_return Clock VENDING MACHINE CONTROLLER Dispense_goodies Return_coins COIN SENSOR Single Coin Slot Q D N COIN DISPENSER Dispense_goodies Return_coins All Deposited Coins Returned Coin Box...
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