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Design Languages >> Verilog-AMS >> bidirectionnal switch with wreal inout in VAMS
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Message started by idriss on Mar 4^th, 2011, 5:02am

Title: bidirectionnal switch with wreal inout in VAMS
Post by idriss on Mar 4^th, 2011, 5:02am

Hi Guys

I would like to model a Switch in verilogams using wreals,
I have 2 inouts wreals A and B, with an On and the thing is the switch is bidirectional, it means the signal can go from A to B or from B to A, in verilog you have specific function to do that, but for wreal is someone knows or have an idea how to that?

Thank you very much
Idris

Title: Re: bidirectionnal switch with wreal inout in VAMS
Post by Marq Kole on Mar 7^th, 2011, 7:21am

Hi Idriss,

The big difference between normal Verilog signals and wreal is that there is no standard resolution function for wreal. Cadence has created a few proprietary extensions that can help you to make bidirectional wreal ports.

Code:

module switch(a, b, s);
inout a, b;
input s;
wreal a, b;
wire s;

real sigA, sigB;

always @(a or b or s) begin
sigA = a;
sigB = b;
if (s == 1'b1)
case (1)
(a === `wrealZState && b !== `wrealZState)
sigA = b;
(a !== `wrealZState && b === `wrealZState)
sigB = a;
endcase
end

assign a = sigA;
assign b = sigB;

endmodule

This is the general idea, anyway. I have not actually tested the above code, I'll leave that up to you. The whole point here is that the special symbols `wrealZState and `wrealXState are used to make the wreals behave similar to other four-state logic in Verilog.

Cheers,
Marq