Request Help - Good example of resolution function

Mon Jan 25, 2010 8:31 am   

Could some VHDL guru please help me ? Could you please direct me to a
good example of a resolution function for multiple drivers ? I have
tried synthesis on Xilinx ISE 11.1 with Spartan 3 and I am getting
multiple drivers problem. Any hints, suggestions would be of immense
help.
Thank you.

Mon Jan 25, 2010 10:34 am   

On Jan 25, 6:31 am, Daku <dakup...@gmail.com> wrote:

A resolution function will not solve this problem. What it means is
you have 2 signals driving the same register, which wont work without
a tri-state driver (which internally synthesises to a mux). Id re-
asses your needs and think more about the underlying hardware rather
than functions to "solve" your problem.

As for great examples of resolution functions - look in the
ieee.std_logic_1164 package - its full of all the resolution functions
for the std_logic type.

Mon Jan 25, 2010 12:26 pm   

Daku <dakupoto_at_gmail.com> writes:


In *theory* this works - it's a well defined solution in
simulation. The problem is that in *practice* the synthesizers of the
world don't bother to try to implement the behaviour of a resolution
function. They typically just give you an error that multiple drivers
exist on the same signal.

You'll have to restructure your design instead.

- Kenn

Mon Jan 25, 2010 1:10 pm   

On Jan 25, 1:31 am, Daku <dakup...@gmail.com> wrote:

If you have multiple processes driving the same signal, you will get
this error.
-Dave Pollum

Mon Jan 25, 2010 6:03 pm   

Daku wrote:

The standard types already have resolution functions.
That is not your problem.

-- Mike Treseler