Introduction to VHDL

Requirement of VHDL

1. Software languages are sequential Sequence of statements are significant, since theygets executed in that order.
2.  Data type are insufficient.
3. In  hardware  events  are  concurrent,  so  a  software
   language  cannot  be  used  for  describing  and
   simulating hardware.

 

Features of HDL

1. Concurrent description
2. Event Scheduling 
3. Hierarchy 
4. Flexible design methodologies 
5. Not technology specific  
6. Large design modeling is easier. 
7. Generic and attributes   
8. Supports both Synchronous and Asynchronous designs  
9. Supports three different description styles  
10. Supports wide range of abstraction levels  
11. User defined library, packages and data types. 

v





General Structure of VHDL
1.Library declaration
2. Package declaration
3. User Defined Library declaration*
4. User Defined Package declaration*
5. Entity Declaration
1. Generic Declaration*
2. Port Declaration
6. Architecture Declaration
7. Configuration Declaration*