LED Blink Example in VHDL for Spartan 6 FPGA board

Here I would like to present LED Blink Example for Spartan 6 XC6SLX9-TQG144 FPGA, that I have from 2012, may be its quiet oldie now, but I want to share all my experience here.

Here is this board I have 2 programmable LED and one 7 segment lcd, we gonna program LED for blinking ~1sec using VHDL. I have 50MHz clock source onboard.

LED_Blink.vhd

-- LED_Blink.vhd for Blinking onboard LED0
library IEEE;
use IEEE_STD_LOGIC_1164.all;
use IEEE.NUMERIC_STD.all;

entity LED_Blink is
        port (
                CLK : in STD_LOGIC;       -- board clock 50MHz
                LED : out STD_LOGIC;      -- onboard LED0
        );
end LED_Blink;

architecture Behavioral of LED_Blink is
        signal counter : unsigned(24 downto 0) := (others => '0');
        signal blink   : STD_LOGIC := '0';
begin
    process(CLK)
    begin
         if rising_edge(CLK) then
             if counter = 25_000_000 -1 then
                     blink <= not blink;
                     counter <= (others => '0');
             else
                 counter <= counter + 1;
            end if;
         end if;
   end process;

   LED <= blink;
end Behavioral;

pinout.ucf

# CLOCK source
NET "CLK" LOC = "P55";

# LED0 pin
NET "LED" LOC = "P127"; # LED0 pin