Verilog Assertion Problem

[New to Verilog]

Hi,

I have to write a module which has tons of parameters. So for
simplicity lets just focus on one paramter. Lets say the parameter
is called: NRCB_G. This parameter is a integer and it's valid values
are only 2, 4 or 8. In order to guarantee correct hook-up of the
module at the higher level (selection of the parameter) I would like
to embedd an assertion inside the module which checks the value given
to the parameter. This assertion should fire if the parameter is not
set to 2, 4 or 8.

I chose to use the assert_proposition assertion and this is how I use
it:

assert_proposition #(0, 0, "CONFIG_ERROR : Valid Values for NRCB_G parameter are : 2, 4 or 8")
NRCB_G_RANGE_CHECK (1'b1, NRCB_G == 2 || NRCB_G == 4 || NRCB_G == 8);

So in case i set the parameter to 2, 4 or 8 everything is fine, the
assertion keeps quite. Now when I chose a value outside the valid range,
the assertion still doesn't fire. So my question is, do i pick
the wrong assertion for these kind of checks, or in case this is the
appropriate assertion, am I using it the wrong way or is there another
switch/parameter I need to set inorder to enable the assertion ?

Thanks in advance for your response !!

 

[Srinivasan Venkataramanan]

Hi,
I suspect 2 things

1. You didn't define ASSERT_ON (required by the OVL modules, else the
assertion is typically masked form the compiler).
2. Since your inputs to the assert_proposition instances are constants, you
have a race condition by which the always block within the OVL doesn't get
triggered, NC seems to work fine in your example, which simulator do you
use?

HTH,
Srinivasan

--
Srinivasan Venkataramanan
Senior Verification Engineer
Software & Silicon Systems India Pvt Ltd. - an Intel company
Bangalore, India

http://www.noveldv.com http://www.deeps.org

I don't speak for Intel
"New to Verilog" <lzm_SpamKiller_@sbcglobal.net> wrote in message
news:3EFBAE25.2080601@sbcglobal.net...

Hi,

I have to write a module which has tons of parameters. So for
simplicity lets just focus on one paramter. Lets say the parameter
is called: NRCB_G. This parameter is a integer and it's valid values
are only 2, 4 or 8. In order to guarantee correct hook-up of the
module at the higher level (selection of the parameter) I would like
to embedd an assertion inside the module which checks the value given
to the parameter. This assertion should fire if the parameter is not
set to 2, 4 or 8.

I chose to use the assert_proposition assertion and this is how I use
it:

assert_proposition #(0, 0, "CONFIG_ERROR : Valid Values for NRCB_G
parameter are : 2, 4 or 8")
NRCB_G_RANGE_CHECK (1'b1, NRCB_G == 2 || NRCB_G == 4 || NRCB_G ==
8);

So in case i set the parameter to 2, 4 or 8 everything is fine, the
assertion keeps quite. Now when I chose a value outside the valid range,
the assertion still doesn't fire. So my question is, do i pick
the wrong assertion for these kind of checks, or in case this is the
appropriate assertion, am I using it the wrong way or is there another
switch/parameter I need to set inorder to enable the assertion ?

Thanks in advance for your response !!