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jelydonut
Joined: 27 Dec 2002
Posts: 368
Helped: 3
Location: Inside your MOM!
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 10 Sep 2003 15:11 Mode/s!m Force, noforce problems. |
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Im trying to force a signal onto a inout for say 100ns, then release it for a output at 200ns then force another signal on to it at 300ns.
What is the best way to accomplish this?
jelydonut
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it_boy
Joined: 18 Jul 2002
Posts: 181
Helped: 4
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| 10 Sep 2003 17:02 |
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| It is very easy to write a testbench in Verilog/VHDL to do this job.
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jelydonut
Joined: 27 Dec 2002
Posts: 368
Helped: 3
Location: Inside your MOM!
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| 10 Sep 2003 17:29 |
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i understand that..
i just am not sure how to unforce at 200ns after doing say a ..
force data 1010101011110000 100
jelydonut
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mueller5321
Joined: 27 Mar 2002
Posts: 22
Location: Germany
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| 16 Sep 2003 22:01 Re: Mode/s!m Force, noforce problems. |
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Try to set it to 'Z'  it should work.
Like
SIG_IO <= '1' after 100ns, 'Z' after 200ns, '0' after 300ns;
Regards
Max
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Al Farouk
Joined: 13 Jan 2003
Posts: 195
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| 21 Sep 2003 14:46 Re: Mode/s!m Force, noforce problems. |
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when you force a signal
#edit -- > force
you will find under Kind three kinds of the signal to be forced
freeze - drive - deposite
use deposite as it means that the signal will take the value you give to it till another source drive it at this time it will take the value drived by the other source. which will help you in your case
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jelydonut
Joined: 27 Dec 2002
Posts: 368
Helped: 3
Location: Inside your MOM!
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| 21 Sep 2003 22:48 Re: Mode/s!m Force, noforce problems. |
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Actually i figured it out.. force w/ -cancel..
Now im working on my tcl scripting..
jelydonut
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Al Farouk
Joined: 13 Jan 2003
Posts: 195
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| 22 Sep 2003 7:38 Re: Mode/s!m Force, noforce problems. |
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| can you please send me your solution in details as it is new for me as I always use deposite to solave this situation (force -deposite ...)
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jelydonut
Joined: 27 Dec 2002
Posts: 368
Helped: 3
Location: Inside your MOM!
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| 22 Sep 2003 13:08 Re: Mode/s!m Force, noforce problems. |
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I think i deleted the .do that I had which used it.. but its rather simple..
If you do a say "force /top/data 16#FF 100" you can then remove that force by doing "force /top/data -cancel 200". So say you write a tcl script for a bidirectional bus. You could make a loop to force data onto it when RD_n = 0 else you could -cancel that force so data can be outputted via the core. But then ya hafta mess with $now to keep track of timing.. unless you did.. force /top/data -cancel [$now] or something like that.. just guessing.. haven't tried it.
jelydonut
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dll_embed
Joined: 04 Sep 2003
Posts: 116
Helped: 1
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| 01 Oct 2003 13:02 Re: Mode/s!m Force, noforce problems. |
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If i understand your problem correctly, a 'noforce' command will also do.
A 'noforce' command is used to remove the effect of any active 'force' commands on the selected HDL items.
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jelydonut
Joined: 27 Dec 2002
Posts: 368
Helped: 3
Location: Inside your MOM!
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| 01 Oct 2003 13:10 Re: Mode/s!m Force, noforce problems. |
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Oh cool.. ok..
didn't realize there was one.. just always used -cancel..
jelydonut
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