-1

Good day! I have a following issue:

I am using Xilinx ISE 14.5 to design for a Spartan 6 FPGA. I noticed that is one of my designs I wasn't able to change the physical pin mapping for a signal. When I changed the line in the .ucf file to another physical pin, re-synthesized and re-implemented the design and uploaded new .bit file the actual signal was still being routed to the old pin.

After that I completely cleared the .ucf file and again rerun the synthesis, implementation etc. and the software didn't even give me a warning about the missing pin declarations.

Here's my code:

entity top is
    port(
        i_clk : IN STD_LOGIC;                                                           
        o_test3 : INOUT STD_LOGIC := '1'
    );

end top;

architecture Behavioral of top is
begin
    p_test: process (i_clk) begin
        if rising_edge(i_clk) then
            o_test3 <= not o_test3;
        end if;
    end process;
end Behavioral;
    enter code here

The .ucf file is completely empty. I expect the software to raise a warning about the missing declaration of i_clk and o_test3. Is my understanding wrong?

If it should raise a warning, is this a bug that can be helped? I am thinking of installing 14.7 version in hopes that it would fix the issue but I thought I'd ask about any possible solutions first. Thanks in advance.

Anthropomorphous Dodecahedron
  • 119
  • 1
  • 5
  • Hi. Stack Overflow is about programming (including HDLs). You question appears to be about how to use a particular EDA tool. I think it might be better asked on the Electronics Stack Exchange site. – Matthew Taylor Sep 22 '20 at 09:20
  • @MatthewTaylor https://stackoverflow.com/help/on-topic mentions that a question about the software tool is allowed – maximus Sep 22 '20 at 15:38
  • @Rakend You're right. Thank you. – Matthew Taylor Sep 23 '20 at 07:04

1 Answers1

0

If no LOC constraint for a pin is provided in a UCF file, ISE will choose a location for the pin. I don't recall if it provides a warning or not.

14.7 offers only minor differences to 14.5 so upgrading is not likely to change anything in your case.

Without the UCF file, we can't really help you with why the LOC constraint isn't being honored.

Travis
  • 1,192
  • 1
  • 8
  • 17