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--Copyright 2013 Friedrich Beckmann, Hochschule Augsburg
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
-- http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
-- Bitclock generator
entity bclk is
port (
clk_i : in std_ulogic;
reset_ni : in std_ulogic;
bclk_o : out std_ulogic;
bclk_falling_edge_en_o : out std_ulogic);
end;
architecture rtl of bclk is
constant max_count : integer := 7;
signal clk_counter : integer range 0 to max_count;
signal bclk_rising_edge_en : std_ulogic;
signal bclk_falling_edge_en : std_ulogic;
begin
bclk_cnt_p : process(clk_i, reset_ni)
begin
if reset_ni = '0' then
clk_counter <= 0;
elsif rising_edge(clk_i) then
if clk_counter = max_count then
clk_counter <= 0;
else
clk_counter <= clk_counter + 1;
end if;
end if;
end process bclk_cnt_p;
edge_comb_p : process(clk_counter)
begin
bclk_rising_edge_en <= '0';
bclk_falling_edge_en <= '0';
if clk_counter = max_count then
bclk_rising_edge_en <= '1';
end if;
if clk_counter = max_count / 2 then
bclk_falling_edge_en <= '1';
end if;
end process edge_comb_p;
bclk_p : process(clk_i, reset_ni)
begin
if reset_ni = '0' then
bclk_o <= '0';
elsif rising_edge(clk_i) then
if bclk_rising_edge_en = '1' then
bclk_o <= '1';
elsif bclk_falling_edge_en = '1' then
bclk_o <= '0';
end if;
end if;
end process bclk_p;
bclk_falling_edge_en_o <= bclk_falling_edge_en;
end; -- architecture
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