电子科技大学：《电子设计自动化技术》课程教学资源（讲义课件）基本术语（李平）

ignal vs Variabl e Signal assignment(<=) receive the assign value after a period ot t ime Variable assignment happens immediately when the statement is executed, no delay (3)

Signal vs Variable „ Signal Assignment (<= ) „ receive the assign value after a period of time „ Variable Assignment „ happens immediately when the statement is executed, no delay (: = )

Key points to remember Function Variables represent local storage Variables is updated immediately the updated value can be used later in the model for further computations Signals represent circuit interconnect Place of declare Variables: Process, Function Procedure Signal Architecture, Package, Entity

Key points to remember „ Function „ Variables represent local storage „ Variables is updated immediately „ the updated value can be used later in the model for further computations „ Signals represent circuit interconnect „ Place of Declare „ Variables : Process, Function,Procedure „ Signal : Architecture,Package,Entity

Visible Variable Signal if define within Entity -visible within the whole Entity if define within architecture-visible Within the whole architecture if define within package -visible within the whole package Make sure that you must have the correct Signal or variable declaration

„ Visible „ Variable „ Signal : if define within Entity - visible within the whole Entity if define within Architecture - visible within the whole Architecture if define within Package - visible within the whole Package „ Make sure that you must have the correct Signal or Variable declaration