HW7_solution - SOLUTION ECE 2504 Introduction to Computer...

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SOLUTION 1 ECE 2504 Introduction to Computer Engineering, Fall 2009 Homework 7 Due date: 18 Oct 09, 11:55pm Show all work. Use Logicworks to draw circuit diagrams. 1. (5 pts) Shown below is the circuit diagram for a 8-to-3 line encoder (The LogicWorks circuit file is also available with this assignment.). It is being used in an assembly line diagnostic circuit. The inputs are connected to active-high sensor outputs that each indicate a different operating fault (e.g. low oil pressure, high temperature and so on). The outputs drive 3 LEDs that represent a binary code indicating which sensor is activated. An alternative would have been to have 8 LEDs, one for each sensor, but there was not room on the control panel. However, sometimes incorrect codes are displayed. Explain why. 0 1 D7 D6 D5 D4 D3 D2 D1 D0 A2 A1 A0 This encoder design assumes that one and only one input will be high at one time, implying that all other input combinations result in “don’t care” conditions. For proper operation, the user must ensure that this is true (which is not the case here; multiple faults could occur at once). To overcome this, a priority encoder could be used in which the inputs are arranged from highest priority to lowest. If a higher priority input is high at the same time as a lower priority input, the encoder output is set to the higher priority. This changes the truth table, K-maps, and final circuit design.
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SOLUTION 2 2. (5 pts) Design a seven-segment decoder that translates 3-bit binary codes into the signals required to drive the seven-segment display found in your chipset. Show all steps of your design process. Truth table: A 2 A 1 A 0 a b c d e f g 0 0 0 0 0 0 0 0 0 1 0 0 1 1 0 0 1 1 1 1 0 1 0 0 0 1 0 0 1 0 0 1 1 0 0 0 0 1 1 0 1 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 0 1 0 0 1 1 0 0 1 0 0 0 0 0 1 1 1 0 0 0 1 1 1 1 K maps: a b 1 A 0 2 00 01 11 10 1 A 0 2 00 01 11 10 0 0 1 0 0 0 0 0 0 0 1 1 0 0 0 1 0 1 0 1 a = A 2 A 1 A 0 + A 2 A 1 A 0 b = A 2 A 1 A 0 + A 2 A 1 A 0 c d 1 A 0 2 00 01 11 10 1 A 0 2 00 01 11 10 0 0 0 0 1 0 0 1 0 0 1 0 0
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This note was uploaded on 10/25/2009 for the course ECE 2504 taught by Professor Klcooper during the Fall '08 term at Virginia Tech.

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HW7_solution - SOLUTION ECE 2504 Introduction to Computer...

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