while loop running +64 how come?

OP #3637563
Rate this post
• ▲ useful
▼ not useful
I have this codepiece
http://pastebin.com/nLyHXp8h
which is giving some problems..
I am getting a error message saying that it is getting looped more thank 
64 times, which i do not understand how that even is possible, since I 
increment the check value inside the loop each time.

I would be very glad if anyone could see where i am going wrong.
Moderator (Company: Titel) #3637622
Rate this post
• ▲ useful
▼ not useful
John Mayer wrote:
> could the problem be that my conditions isn't constant?
No.
The problem ist, that you think VHDL is a programming language like C. 
Let me tell you: it isn't. It is far, far away from C or Basic or 
something like that!

Lets take this:
1
       while (pointer <= (3)) loop
2
               LED <= LISTEN(pointer);
3
               pointer := pointer + 1;
4
       end loop;
You will not be able to get this on hardware. It is just a 
"combinatorial loop". Do you want to know more? Try that with google 
translator:
http://www.lothar-miller.de/s9y/archives/42-Kombinatorische-Schleifen.html

The whole coding style is completely software based (variables, 
functions...) and this will lead to nowhere in VHDL. Did you do the 
blinking LED (= "Heollo Wolrd!" of hardware) and a chasing light before 
this code?

Pls attach your complete vhdl file here. then we can have a close look 
at it...
Moderator (Company: Titel) #3637890
Rate this post
• ▲ useful
▼ not useful
John Mayer wrote:
> complete code:
> http://pastebin.com/Z4NxaeNd
I will not read this that, because
Lothar Miller wrote:
> Pls attach your complete vhdl file here. then we can have a close look
> at it...
However...

> How come?
Your "problem" is well known and called "wrap around". Workaround: just 
don't try to access an index behind the last element.

Reply

Note: the original post is older than 6 months. Please don't ask any new questions in this thread, but start a new one.

Formatting
  • [c]C-Code[/c]
  • [vhdl]VHDL-Code[/vhdl]
  • [code]code in other languages, ASCII drawings[/code]
  • [math]formula (LaTeX syntax)[/math]
  • [[Title]] – link to an article
  • Link to another post: right-click its post ID (#8078628), copy the address, paste it into the text

More about formatting

Post long source code as an attachment, not in the text.

Already registered? Log in

Not shown to anyone. We send you a link; your post appears once you confirm it there.

By submitting you create a free account and accept the terms of use.