please help! state machine

Jan 03, 2004 4 Replies
S

Hello!



I've got a strange problem that I don't know any solution for - up to now I tried everything, but it didn't work. The state machine always stops to go to the next state - I really don't understand why.



I've got a state machine with 5 states: SEL_EP, WRITE_INIT, WRITE_DATA, VAL_BUF and IDLE. It gets stuck after the WRITE_INIT state, just remains in the WRITE_INIT state all the time. WHY???? The 2nd (smaller) problem is, that the data at write_out comes one clock cycle too late. I understand why, but how can i change this?



I don't know if it's a good idea to solve my problem with my kind of code, i'm an "advanced beginner" and as I am used to program "sequential programming languages" I've got big problems with doing sequential things in vhdl. What is the easy way to do things one after the other, e.g. write one byte after the other? (also to be synthesizable).



I put the code at

formatting link
because it's quite long to put it here. (don't be afraid - no virus!)



Please help me! I really don't know where to go on.



Thank you, Simone


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R

What program you using ..Quartus?

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S

: What program you using ..Quartus?

Xilinx ISE Webpack 5.2i with ServicePack, Modelsim XE 5.6e Starter.

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M

You should be able to use Modelsim to duplicate the lockup, and therefore see what input to the state machine is causing you the problem.

BTW, you may not be getting what you expect with at least one of your procedures since the clocked part of the procedure is within another if statement.

Also, the proper newsgroup for this type of question is

news:comp.lang.vhdl

Have fun,

Marc

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J

For starters make sure that your sensitivity list is complete. It isn't at present and some simulators will simply ignore statements where the "input" signals are not in the sensitivity list. Synthesisers should do something similar in theory but most "assume" the sensitivity list.

John Adair Enterpoint Ltd.

This message is the personal opinion of the sender and not that necessarily that of Enterpoint Ltd.. Readers should make their own evaluation of the facts. No responsibility for error or inaccuracy is accepted.

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