what's wrong between QII6.1 and QII9.0

Question

wire a_cs_n;

wire b_cs_n;

assign a_cs_n = (addr[19:18]==2'b01)? 1'b0 : 1'b1;

assign b_cs_n = (addr[19:18]==2'b00 && addr[17:16]==2'b10) ? 1'b0 : 1'b1;

assign dout = ({16 {a_cs_n}} | 16'haaaa ) & ({16 {b_cs_n}} | 16'hbbbb) ;

With QII 6.1,dout can get 16'haaaa or 16'hbbbb.But with Qii 9.0,dout cannot get 16'haaaa。

We don't change the code.But get the different result.

Why?

Thank you very much!

altera_forum · Answer

--- Quote Start ---

wire a_cs_n;

wire b_cs_n;

assign a_cs_n = (addr[19:18]==2'b01)? 1'b0 : 1'b1;

assign b_cs_n = (addr[19:18]==2'b00 && addr[17:16]==2'b10) ? 1'b0 : 1'b1;

assign dout = ({16 {a_cs_n}} | 16'haaaa ) & ({16 {b_cs_n}} | 16'hbbbb) ;

With QII 6.1,dout can get 16'haaaa or 16'hbbbb.But with Qii 9.0,dout cannot get 16'haaaa。

We don't change the code.But get the different result.

Why?

Thank you very much!

--- Quote End ---

Hi,

I run a test with Quartus II 9.0 (Full version). I looks pretty in my project.

I have the project attached. Maybe I made a mistake in the project ?

Kind regards

GPK

altera_forum · Answer

Why don't you write: always @ (*) begin   if (a_cs_n) dout &lt;= 16'haaaa;   if (b_cs_n) dout &lt;= 16'hbbbb; end

Forum Discussion