Electronic – high impedance in rtl verilog

verilog

I am designing a shift register. It has a control signal called RD which is asynchronous (so cant use it inside the procedural block), the whole point is my n-1 bit shift register is value of the input if RD ==1 or else it has high impedance; I am not sure how to write the assign the high impedance value because my n bit is a parameter so I cant define the no of bits.

inout [n-1:0] Data;
input RD;

reg [n-1:0] register; //my register

Example: Data = (RD==1'b1)? [n-1:0] register: 'z ;

its giving me a error. How can I define that if RD is 1 then I need to see what is there inside the register and if its 0 then, it should be high impedance. Can anyone help?

Best Answer

Unless you are using SystemVerilog, you cant declare a constant like that.

Instead use the replication operator. {(WIDTH){1'bz}} is a WIDTH bit wise constant of all z's. Just replace the width with however wide you need (can be a parameter).

Furthermore, it should be register[n-1:0] not [n-1:0]register.

The following should work:

assign Data = (RD == 1'b1) ? register : {(n){1'bz}};
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