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Basic VHDL quiz โ Part 3
Test your progress with this VHDL quiz after completing tutorials 12-17 from the Basic VHDL Tutorial series!
Basic VHDL quiz
Have fun and learn from this VHDL and FPGA design quiz with 28 questions for beginners and intermediate learners in random order.
All questions include an explanation for the correct answer that will be shown after you make your selection.
How to use a While loop in VHDL
In the previous tutorial, we learned how to use a For-Loop to iterate over an integer range. But what if we want a more detailed control of the loop than just a fixed integer range? We can use a While-Loop for this. The While-Loop will continue to iterate over the enclosed code as long as…
How to create a clocked process in VHDL
The vast majority of VHDL designs uses clocked logic, also known as synchronous logic or sequential logic. A clocked process is triggered only by a master clock signal, not when any of the other input signals change. The basic building block of clocked logic is a component called the flip-flop. There are different variants of…
How to use conditional statements in VHDL: If-Then-Elsif-Else
In the previous tutorial we used a conditional expression with the Wait Until statement. The expression ensured that the process was only triggered when the two counter signals where equal. But what if we wanted the program in a process to take different actions based on different inputs? The If-Then-Elsif-Else statements can be used to…
How to use Wait On and Wait Until in VHDL
In the previous tutorial we learned the main differences between signals and variables. We learned that signals have a broader scope than variables, which are only accessible within one process. So how can we use signals for communication between several processes? We have already learned to use wait; to wait infinitely, and wait for to…
First of all, thank you so very much!
These are by far the most comprehensible tutorials I have come across like ever!
Brilliant work.
So here my two cents out of gratitude:
Basic VHDL Quiz โ part 4
Which statement is not true?
Answer 3 : The return statement cannot be omitted.
-> Correct
So the return statement CAN be omitted???
“Unlike in most other programming languages, the return keyword is mandatory in functions in VHDL.”
Confused by double negation. Me or you ๐
Good catch! I’ve changed the answer now. I was trying to make you think, but in the process I confused myself too ๐
“The return-keyword cannot be used in a procedure”. I believe that this is incorrect, e.g.
https://web.archive.org/web/20200629023040/http://vhdl.renerta.com:80/source/vhd00060.htm
It is true, of course, that you cannot return a value with it, that’s the only (?) difference between procedures and functions. But, as in other languages, you can use “return” as control flow statement to “force an exit”.
You are right! I missed the possibility of using return statements in procedures without returning a value. According to the Renata link you posted, functions must return a value, while procedures can have return statements, but then without a return value.
I am changing this question.