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Libs/Sequential/hdl/edgeDetector_arch.vhd

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+--------------------------------------------------------------------------------
+-- Copyright 2014 HES-SO Valais Wallis (www.hevs.ch)
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation; either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- This program IS distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+-- GNU General Public License for more details.
+-- You should have received a copy of the GNU General Public License along with
+-- this program. If not, see <http://www.gnu.org/licenses/>
+--------------------------------------------------------------------------------
+-- EdgeDetector
+--   Detect rising and falling edges of a signal.
+--
+--   Created on 2014-04-02
+--
+--   Version: 1.0
+--   Author: Oliver A. Gubler (oliver.gubler@hevs.ch)
+--------------------------------------------------------------------------------
+ARCHITECTURE arch OF edgeDetector IS
+  
+  SIGNAL signal_s : std_ulogic;
+  SIGNAL rising_detected_s : std_ulogic;
+  SIGNAL falling_detected_s : std_ulogic;
+
+BEGIN
+
+  -- sync
+  reg : PROCESS (reset,clock)
+  BEGIN
+    IF reset = '1' THEN
+      signal_s <= '0';
+    ELSIF rising_edge(clock) THEN
+      signal_s <= input;  
+    END IF;    
+  END PROCESS reg ;
+  
+  -- edge detection
+  rising_detected_s <= input AND NOT signal_s; 
+  falling_detected_s <= NOT input AND signal_s;
+  
+  -- output
+  rising_detected <= rising_detected_s;
+  falling_detected <= falling_detected_s;
+  
+END ARCHITECTURE arch;