Contents
How are signal assignment statements executed?
The sequential signal assignment has the same syntax as the simple form of the concurrent signal assignment; the difference between them results from context. The sequential signal assignment has the following syntax: signal <= expression [after delay];
What are the concurrent statements?
Concurrent statements are used to define interconnected blocks and processes that jointly describe the overall behavior or structure of a design. Concurrent statements execure asynchronously with respect to each other.
Which statement is used to make copies of concurrent statement?
The component instantiation statement references a pre- viously defined (hardware) component. Finally, the generate statement creates multiple copies of any concurrent statement.
What are the concurrent signal assignment statements in VHDL?
This article will review the concurrent signal assignment statements in VHDL. This article will first review the concept of concurrency in hardware description languages. Then, it will discuss two concurrent signal assignment statements in VHDL: the selected signal assignment and the conditional signal assignment.
When to use variable assignment or sequential signal assignment?
The variable assignment (:=) executes immidiatly and can be used to e.g. temporarely store some data inside a process. Sequential signal assignment (<=), as opposed to sequential variable assignment (:=), sequentially schedules an event one delta delay later for the value of the signal to be updated.
Can a process be similar to a concurrent procedure?
A process can not be similarly defined in a package and may have to be physically copied. A process has some additional capability not available in a concurrent procedure. A sequential signal assignment statement is also a concurrent signal assignment statement.
How are two processes using the same signal?
These 2 processes use the same signal, but one of them changes the value of that signal. The simulator is only be able to perform one process at the time due to a sequential simulation model (not to confuse with the concurrent model of vhdl). So if process A is simulated first and A changes the signal, B would have the wrong signal value.