22-09-2012, 05:10 PM
VHDL Coding Basics
2code_basic.ppt (Size: 1.16 MB / Downloads: 50)
VHDL features
Case insensitive
inputa, INPUTA and InputA are refer to same variable
Comments
‘--’ until end of line
If you want to comment multiple lines, ‘--’ need to be put at the beginning of every single line
Statements are terminated by ‘;’
Signal assignment:
‘<=’
User defined names:
letters, numbers, underscores (‘_’)
start with a letter
VHDL structure
Library
Definitions, constants
Entity
Interface
Architecture
Implementation, function
VHDL - Entity
Input port can only be read inside architecture
input1 <= temp; -- This statement is NOT allowed
Output port can only be written inside architecture
temp <= output1; -- This statement is NOT allowed
Definitions of the Description Methods
Structural Description Method: expresses the design as an arrangement of interconnected components
It is basically schematic
Behavioral Description Method: describes the functional behavior of a hardware design in terms of circuits and signal responses to various stimuli
The hardware behavior is described algorithmically
Data-Flow Description Method: is similar to a register-transfer language
This method describes the function of a design by defining the flow of information from one input or register to another register or output
2code_basic.ppt (Size: 1.16 MB / Downloads: 50)
VHDL features
Case insensitive
inputa, INPUTA and InputA are refer to same variable
Comments
‘--’ until end of line
If you want to comment multiple lines, ‘--’ need to be put at the beginning of every single line
Statements are terminated by ‘;’
Signal assignment:
‘<=’
User defined names:
letters, numbers, underscores (‘_’)
start with a letter
VHDL structure
Library
Definitions, constants
Entity
Interface
Architecture
Implementation, function
VHDL - Entity
Input port can only be read inside architecture
input1 <= temp; -- This statement is NOT allowed
Output port can only be written inside architecture
temp <= output1; -- This statement is NOT allowed
Definitions of the Description Methods
Structural Description Method: expresses the design as an arrangement of interconnected components
It is basically schematic
Behavioral Description Method: describes the functional behavior of a hardware design in terms of circuits and signal responses to various stimuli
The hardware behavior is described algorithmically
Data-Flow Description Method: is similar to a register-transfer language
This method describes the function of a design by defining the flow of information from one input or register to another register or output