VHDL Programming

162 Chapter Six c_opd a_ipd b_ipd a_ipd b_ipd a_ipd b_ipd c_opd c_opd c_opd and2 and2 and2 Figure 6-2 Gate Array Logic with Inpu ...

Predefined Attributes 163 If the optional time expression for attribute ’DELAYEDis not specified, 0 ns is assumed. A signal dela ...

164 Chapter Six A delayed version of the clkinput is used to trigger the hold-check. The clkinput is delayed by the amount of th ...

Predefined Attributes 165 0 102030 4050607080 A B Figure 6-3 Example Showing ’DELAYED (10ns). At the first two changes in signal ...

166 Chapter Six A B One Delta wide Figure 6-4 Example Showing ’DELAYED (0 ns). In both cases, the IFstatement detects the rising ...

Predefined Attributes 167 END PROCESS int1_proc; int2_proc: PROCESS BEGIN . . . WAIT ON trigger2;-- outside trigger signal WAIT ...

168 Chapter Six END PROCESS; END test; This example shows how a priority mechanism could be modeled for an interrupt handler. Pr ...

Predefined Attributes 169 attribute is another of the attributes that creates a signal where it is used. Attribute ’TRANSACTIONc ...

170 Chapter Six type of type coloris type color. The statement color’LEFTreturns the value red. In the last assignment,color_gun ...

Predefined Attributes 171 The ’REVERSE_RANGEattribute works similar to the ’RANGEattri- bute,except that the range is returned i ...

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Chapter 7 Configurations Configurations are a primary design unit used to bind component instances to entities. For structural m ...

174 Chapter Seven The configuration can also be used to provide a very fast substitution capability. Multiple architectures can ...

Configurations 175 END IF; END IF; data_out <= count; END PROCESS; END count_255; ARCHITECTURE count_64k OF counter IS BEGIN ...

176 Chapter Seven 16-bit counter. The architectures specify a synchronous counter with a synchronous loadand clear. All operatio ...

Configurations 177 Decode A B EN Q0 Q1 Q2 Q3 Figure 7-1 Symbol for Decoder Example. ENTITY inv IS PORT( a : IN std_logic; PORT( ...

178 Chapter Seven EN A B Q0 Q1 Q2 Q3 nota notb Figure 7-2 Gate Level Schematic for Decoder. ARCHITECTURE structural OF decode IS ...

Configurations 179 PORT MAP(nota, en, b, Q2); A4 : and3 PORT MAP(a, en, b, Q3); END structural; When all of the entities and arc ...

180 Chapter Seven This configuration specifies which configuration to use for each compo- nent in architecture structuralof enti ...

Configurations 181 END FOR; END FOR; END decode_eacon; This configuration looks very similar to the lower-level configuration st ...