source: firmware/FTU/counter/FTU_rate_counter.vhd@ 9912

----------------------------------------------------------------------------------
-- Company:        ETH Zurich, Institute for Particle Physics
-- Engineer:       Q. Weitzel, P. Vogler
-- 
-- Create Date:    10:38:40 08/18/2010 
-- Design Name: 
-- Module Name:    FTU_rate_counter - Behavioral 
-- Project Name: 
-- Target Devices: 
-- Tool versions: 
-- Description:    Entity to count trigger and sum patch rates of FTU board
--
-- Dependencies: 
--
-- Revision: 
-- Revision 0.01 - File Created
-- Additional Comments: 
--
----------------------------------------------------------------------------------

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

library ftu_definitions;
USE ftu_definitions.ftu_array_types.all;
USE ftu_definitions.ftu_constants.all;

---- Uncomment the following library declaration if instantiating
---- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity FTU_rate_counter is
  port(
    clk        : in  std_logic;
    cntr_reset : in  std_logic;
    trigger    : in  std_logic;
    prescaling : in  std_logic_vector(7 downto 0);
    counts     : out integer range 0 to 2**16 - 1 := 0;
    overflow   : out std_logic := '0';
    new_rate   : out std_logic
  );
end FTU_rate_counter;

architecture Behavioral of FTU_rate_counter is

  signal counting_period : integer range 0 to 128*COUNTER_FREQUENCY := 128*COUNTER_FREQUENCY;
  signal period_finished : std_logic := '0';
  signal trigger_counts  : integer range 0 to 2**16 - 1 := 0;
  signal clk_1M_sig      : std_logic;
  signal overflow_sig    : std_logic := '0';
  signal new_rate_sig    : std_logic := '0';
  
  component Clock_Divider
    port(
      clock_in  : IN  STD_LOGIC;
      clock_out : OUT STD_LOGIC
    );
  end component;
  
begin

  Inst_Clock_Divider : Clock_Divider
    port map (
      clock_in  => clk,
      clock_out => clk_1M_sig
    );
  
  process(cntr_reset, clk_1M_sig)

    variable clk_cntr : integer range 0 to 128*COUNTER_FREQUENCY := 0;

  begin

    if cntr_reset = '1' then
          
      clk_cntr := 0;      
      period_finished <= '1';
      new_rate_sig <= '0';
      counts <= 0;
      overflow <= '0';
      
    elsif rising_edge(clk_1M_sig) then
      
      if (clk_cntr < counting_period - 1) then
        clk_cntr := clk_cntr + 1;
        period_finished <= '0';
        new_rate_sig <= '0';
      else
        clk_cntr := 0;
        period_finished <= '1';
        new_rate_sig <= '1';
        counts <= trigger_counts;
        overflow <= overflow_sig;
      end if;
    end if;
  end process;

  process(trigger, period_finished)
  begin
    if period_finished = '1' then
      trigger_counts <= 0;
      overflow_sig <= '0';
    else
      if rising_edge(trigger) then
        if (trigger_counts < 2**16 - 1) then 
          trigger_counts <= trigger_counts + 1;
        else
          trigger_counts <= 0;
          overflow_sig <= '1';
        end if;
      end if;
    end if;
  end process;

  process(cntr_reset, prescaling)
  begin
    if rising_edge(cntr_reset) then
      --formula to calculate counting period from prescaling value
      if (prescaling = "00000000") then
        counting_period <= COUNTER_FREQUENCY / (2 * CNTR_FREQ_DIVIDER);
      else
        counting_period <= ((conv_integer(unsigned(prescaling)) + 1) / 2) * (COUNTER_FREQUENCY / CNTR_FREQ_DIVIDER);
      end if;
    end if;
  end process;
  
  new_rate <= new_rate_sig;
  
end Behavioral;

----------------------------------------------------------------------------------

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

library ftu_definitions;
USE ftu_definitions.ftu_array_types.all;
USE ftu_definitions.ftu_constants.all;

entity Clock_Divider is
  generic(
    divider : integer := INT_CLK_FREQUENCY / COUNTER_FREQUENCY
  );
  port(
    clock_in  : in  std_logic;
    clock_out : out std_logic := '0'
  );
end entity Clock_Divider;

architecture RTL of Clock_Divider is

begin
    
  process (clock_in)
    variable Z: integer range 0 to divider - 1;
  begin
    if rising_edge(clock_in) then
      if (Z < divider - 1) then
        Z := Z + 1;
      else
        Z := 0;
      end if;
      if (Z = 0) then
        clock_out <= '1';
      end if;
      if (Z = divider / 2) then
        clock_out <= '0';
      end if;
    end if;
  end process;

end architecture RTL;