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Unformatted text preview: Lab 5: 8bit Counters Derek W. Johnson ECEN 248506 Aaron Hill February 29, 2008 Objectives This lab will increase the students understanding of counters and clocks. The lab will explore the differences between a debounced clock and a nondebounced clock. The student will also design a function for writing a binary number to a digital display. Design 1. The 7Segment Display In order to write an 8bit binary number to a digital display (in hexadecimal form), the number must be divided into two 4bit numbers. Each number will output to its own digital display. Thus, a system of equations needs to be designed to convert a 4bit number to the proper hexadecimal digit. The first step in designing such a device is to write out the truth table. Notice that a segment lights up when its signal goes low. Table 1: 7Segment Display Truth Table X 3 X 2 X 1 X A B C D E F G 1 1 1 1 1 1 1 1 1 2 1 1 1 1 3 1 1 1 4 1 1 1 1 1 5 1 1 1 1 6 1 1 1 1 7 1 1 1 1 1 8 1 1 9 1 1 1 1 A 1 1 1 1 b 1 1 1 1 C 1 1 1 1 1 1 d 1 1 1 1 1 E 1 1 1 1 1 1 F 1 1 1 Figure 1: 7Segment Display Layout B C F E A G D The logic equations for each segment can be found by creating Karnaugh maps. Table 2: Kmap for A X 3 X 2 X 1 X 1 1 1 10 00 1 01 1 1 11 1 10 A = /X 3 *X 2 */X 1 */X + /X 3 */X 2 */X 1 *X + X 3 *X 2 */X 1 *X + X 3 */X 2 *X 1 *X . Table 3: Kmap for B X 3 X 2 X 1 X 1 1 1 10 00 1 01 1 11 1 1 10 1 1 B = X 3 *X 1 *X + X 3 *X 2 */X + X 2 *X 1 */X + /X 3 *X 2 */X 1 *X ....
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 Spring '08
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