It's clear that the concurrent VHDL statements will allow us to easily describe a circuit such as the one in Figure 1 above.In a future article, we'll see that the sequential VHDL statements allow us to have a safer description of sequential circuits.
It's clear that the concurrent VHDL statements will allow us to easily describe a circuit such as the one in Figure 1 above.In a future article, we'll see that the sequential VHDL statements allow us to have a safer description of sequential circuits.Tags: Nestle Case Study Change ManagementRomeo And Juliet Identity EssayBlank Business PlanIntroduction To AssignmentQuantum Mechanics Homework SolutionsWas Assigned
As a result, we can rewrite the architecture section of the above code as below: Since these statements are evaluated at the same time, we call them concurrent statements.
This type of code is quite different from what we have learned in basic computer programming where the lines of code are executed one after the other.
Furthermore, using the sequential VHDL, we can easily describe a digital circuit in a behavioral manner.
This capability can significantly facilitate digital hardware design.
Similarly, you can verify the intended operation for the rest of the simulation interval.
Example 2: Use the “with/select” statement to describe a 4-to-2 priority encoder with the truth table shown below.To understand the difference between the concurrent statements and the sequential ones, let’s consider a simple combinational circuit as shown in Figure 1.If we consider the operation of the three logic gates of this figure, we observe that each gate processes its current input(s) in an independent manner from other gates.The following VHDL code can be used to describe the above truth table: library IEEE; use IEEE. ALL; entity prio_encoder1 is Port ( x : in STD_LOGIC_Vector(3 downto 0); y : out STD_LOGIC_Vector(1 downto 0); v : out STD_LOGIC); end prio_encoder1; architecture Behavioral of prio_encoder1 is begin with x select y The ISE simulation is shown in Figure 5.The “when/else” statement is another way to describe the concurrent signal assignments similar to those in Examples 1 and 2.The following figure shows the simulation of this code using the Xilinx ISE simulator.(In case you’re not familiar with ISE, see this tutorial.) As shown in this figure, from 0 nanosecond (ns) until 300 ns the select input, .For example, consider the following MATLAB code: While the VHDL code describing Figure 1 was executed concurrently, the above MATLAB code is evaluated sequentially (i.e., one line after the other).VHDL supports both the concurrent statements and the sequential ones.Since the syntax of this type of signal assignment is quite descriptive, let’s first see the VHDL code of a one-bit 4-to-1 multiplexer using the “when/else” statement and then discuss some details.Example 3: Use the when/else statement to describe a one-bit 4-to-1 multiplexer.