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warning "has no driver"

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Dave Fontes

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hi guys, i'm facing a little problem , i cannot understand where this warning comes from
the code is the fowling

Code:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

use work.set_of_data_items.all;	

entity merge64to64 is
  Port (	 	input_1items	: in set_of_8items;
				input_2items	: in set_of_8items;
				input_3items	: in set_of_8items;
				input_4items	: in set_of_8items;

				input_5items	: in set_of_8items;
				input_6items	: in set_of_8items;
				input_7items	: in set_of_8items;
				input_8items	: in set_of_8items;

				sorted			: out set_of_64items);

end merge64to64;

architecture Behavioral of merge64to64 is

signal sorted1,sorted2	 	: set_of_32items;
signal out1_in2,out2_in3	: set_of_64items;
signal out3_in4,out4_in5	: set_of_64items;
signal out5_in6				: set_of_64items;

begin 


sort32items1: entity work.merge32to32
						port map(input_1items,input_2items,input_3items,input_4items,sorted1);
						
sort32items2: entity work.merge32to32
						port map(input_5items,input_6items,input_7items,input_8items,sorted2);


stage6:
			for i in 8*N/2-1 downto 0 generate
				group1stage6:	entity work.Comparator
									port map(sorted1(i),sorted2(i),out1_in2(i),out1_in2(i+32));
									
				check1stage6:	if(i>=16) generate 
									group2stage6:	entity work.Comparator
														port map(out1_in2(i),out1_in2(i+16),out2_in3(i),out2_in3(i+16));
								end generate;
				check2stage6:	if(i<16) generate
									out2_in3(i)<=out1_in2(i);
									out2_in3(i+48)<=out1_in2(i+48);
								end generate;

				check3stage6:	if(i>=24) generate
									group3stage6:	entity work.Comparator
														port map(out2_in3(i),out2_in3(i+8),out3_in4(i),out3_in4(i+8));
								end generate;
				check4stage6:	if(i<24) generate
									out3_in4(i)<=out2_in3(i);
									out3_in4(i+40)<=out2_in3(i+40);
								end generate;

				check5stage6:	if(i>=4 and i<8) generate
									on_stage6: for j in 0 to 6 generate
													group4stage5:	entity work.Comparator
																			port map(out3_in4(j*8+i),out3_in4(j*8+i+4),out4_in5(j*8+i),out4_in5(j*8+i+4));
									end generate on_stage6;
								end generate;

				check6stage6:	if(i<4) generate
									out4_in5(i)<=out3_in4(i);
									out4_in5(i+60)<=out3_in4(i+60);
								end generate;
--
				check7stage6:	if(i< 15) generate
									on2_stage6:	for k in 0 to 1 generate
											group5stage6:	entity work.Comparator
																port map(out4_in5(2+i*4+k),out4_in5(2+i*4+k+2),out5_in6(2+i*4+k),out5_in6(2+i*4+k+2));
									end generate on2_stage6;
								end generate;

				check8stage6:	if(i<2) generate
										out5_in6(i)<=out4_in5(i);
										out5_in6(i+62)<=out4_in5(i+62);
								end generate;

end generate stage6;
sorted<=out5_in6;


end behavioral;


the warning is the fowlling

WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><31>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><30>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><29>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><28>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><27>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><26>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><25>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><24>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><23>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><22>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><21>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><20>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><19>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><18>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><17>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><16>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><15>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><14>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><13>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><12>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><11>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><10>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><9>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><8>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><7>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><6>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><5>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><4>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><3>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><2>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><1>' has no driver
WARNING:NgdBuild:452 - logical net 'sort64items/sorted<17><0>' has no driver

thanks for the help :)
 

"has no driver" means there is no logic connected to it.

The result of which usually is that whatever comes AFTER that will be optimized away.

So sort64items/sorted<17> looks like a 32-bit vector, and by the looks of it will have some siblings like sort64items/sorted<16> etc. So presumably you did hook up sort64items/sorted<16>, but did not hook up sort64items/sorted<17>. That's just a guess of course, without seeing any code.

Hope that helps.
 

the thing is, im pretty sure m'm evoking the sorted<17> and giving it a value :s
 

the thing is, im pretty sure m'm evoking the sorted<17> and giving it a value :s
I'm pretty sure that your VHDL compiler is better in determining undriven signals than you and me.

But because the posted code is incomplete , we can't check the issue.
 

I'm pretty sure that your VHDL compiler is better in determining undriven signals than you and me.

But because the posted code is incomplete , we can't check the issue.


incomplete ? oh maybe im checking it wrong, but this is the module that creates the warning, more especificaly

Code:
				check7stage6:	if(i< 15) generate
									on2_stage6:	for k in 0 to 1 generate
											group5stage6:	entity work.Comparator
																port map(out4_in5(2+i*4+k),out4_in5(2+i*4+k+2),out5_in6(2+i*4+k),out5_in6(2+i*4+k+2));
									end generate on2_stage6;
								end generate;

				check8stage6:	if(i<2) generate
										out5_in6(i)<=out4_in5(i);
										out5_in6(i+62)<=out4_in5(i+62);
								end generate;

and up there, i pretty sure, i set the value of out5_in6(17) wich is later pass to sorted.
 

Incomplete means missing components and constant definitions needed to check it.
 

Well I'm not surprised that the OP is back asking for help on the exact same problem they had previously. see: https://www.edaboard.com/threads/313819/#post1341892 Previously they didn't post all the code for the module reporting the error and the constant definitions. Then they posted code for a different component and a new top level using a different component.

The OP didn't get a fix then and unless the they actually posts all the code for the design that has a problem, all anyone on the forum can do is guess.
 
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    FvM

    Points: 2
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the thing is, im pretty sure m'm evoking the sorted<17> and giving it a value :s

I'm pretty the sure the tools will take your opinion into consideration. And after due consideration, it will implement what you requested instead of what you think you requested. ;)

Tell you what, go look for this signal in the synthesized results and see which one won out. Opinion vs reality. Place your bets!
 

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