Disable Global Buffer

Nov 27, 2004 1 Replies

Hello,



I am somewhat new to vhdl, xilinx, etc. The board I am working with is the Spartan 2s50-pq208-6. I have created my design in VHDL and went to assign the pins. I have a signal "reset" that I need to drive off of one of the boards switches.



The problem is that XILINX has determined that the "reset" signal is a global clock signal and can only use of the the 4 global clock signals on the board.


How do I prevent this from happening.



I am using Xilinx Free Webpack 6.3.



Since I am new to all of this, I am not sure what to post. Here is my code: entity prj2v3 is



--d comes from MC



--p comes from peri port(ceAL, a0, rdAL, wrAL, reset, stbAL: in STD_LOGIC; ibf, intr, bufctrl, here: out STD_LOGIC; d: inout STD_LOGIC_VECTOR(7 downto 0):=(others=>'Z'); p: in STD_LOGIC_VECTOR(7 downto 0)); --attribute syn_noclockbuf of reset : signal is true; end prj2v3;



architecture Behavioral of prj2v3 is


signal ctr: std_logic_vector(0 to 1):="00"; --ctr.0=MODE ctr.1==INTE signal str: std_logic_vector(0 to 2):="000"; ---str.0==IBF str.1==INTE str.2==INTR signal data: std_logic_vector(7 downto 0):="00000000";



--signal here: std_logic:='0';



--signal here2: std_logic:='0'; begin ctr(0)


"Aaron" schrieb im Newsbeitrag news: snipped-for-privacy@posting.google.com...

Hmm, you are using reset to latch data, so reset is a clock. Clock should be feed into the FPGA using the dedicated clock buffer pins (GCLK). But there are always other ways. If you want to use a normal IO, use the following lines.

-- this is to be placed between architecture Behavioral of prj2v3 is

component ibuf port is (I : in std_logic; O: out std_logic) end component;

-- and begin

label_ibuf: ibuf port map(I : reset, O: reset_int);

this will do the trick. Now use reset_int for your logic. But be aware that distributing a clock on non-clock nets can play you nasty tricks.

Regards Falk

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