Exclusive-OR and Exclusive-NOR Gates Chapter 6 Exclusive-OR and Exclusive-NOR Gates Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

The Exclusive-OR Gate HIGH output if one input or the other input is HIGH, but not both. Logic Symbol - See Figure 6-3 Truth Table - See Table 6-1 Boolean equation X = AB + AB Comparator Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Figure 6-3 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

William Kleitz Digital Electronics with VHDL, Quartus® II Version Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

The Exclusive-NOR Gate The complement of the exclusive-OR Logic Symbol - See Figure 6-4 Truth Table - See Table 6-2 Boolean equation X = AB + A B Comparator Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Figure 6-4 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

William Kleitz Digital Electronics with VHDL, Quartus® II Version Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Parity Generator / Checker Electrical noise in the transmission of binary information can cause errors Parity can detect these types of errors Parity systems odd parity even parity Adds a bit to the binary information Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Parity Generator / Checker See Figure 6-8 Error indicator output Even- and odd-parity generators see Figure 6-9 Integrated-Circuit Parity Generator/Checker 74280 TTL IC Function Table - see Figure 6-12 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Figure 6-8 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Figure 6-9 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Figure 6-12 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

System Design Applications See example 6-5, 6-6, and 6-7 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Figure 6-13 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Figure 6-14 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Figure 6-15 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

CPLD Design Applications with VHDL Used to simulate combinations of inputs and observe the resulting output to check for proper design operation. See examples 6-8, 6-9, and 6-10 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

CPLD Design Applications with VHDL Example 6-8, the 74280 parity geneator using the Quartus II Macrofunction build a block design file build a vector waveform file provide a binary count on the 9 bit input so that several combinations of odd and even parity are generated Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Figure 6-16 Figure 6-17 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

CPLD Design Applications with VHDL Example 6-9, parallel binary comparator reproduce the parallel binary comparator of example 6-6 complete the circuit using bdf and VHDL entry methods test operation Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Figure 6-18 Figure 6-19 Figure 6-20 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

CPLD Design Applications with VHDL Example 6-10, CPLD controlled inverter reproduce the controlled inverter of example 6-7 complete the circuit using bdf and VHDL entry methods test operation Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Figure 6-21 Figure 6-22 Figure 6-23 Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Summary The exclusive-OR gate outputs a HIGH if one or the other inputs, but not both, is HIGH. The exclusive-NOR gate outputs a HIGH if both inputs are HIGH or if both inputs are LOW. Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Summary A parity bit is commonly used for error detection during the transmission of digital signals. Exclusive-OR and NOR gates are used in applications such as parity checking, binary comparison and controlled complementing circuits. Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version

Summary CPLDs can be used to implement circuits containing the exclusive gates Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. William Kleitz Digital Electronics with VHDL, Quartus® II Version