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Libs/Common/hdl/edgeDetector_rtl.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.
+--
+--------------------------------------------------------------------------------
+-- History:
+-- v0.1 : guo 2014-04-02 -- Initial version
+-- v1.0 : cof 2019-10-02 -- Updated symbol
+--------------------------------------------------------------------------------
+ARCHITECTURE RTL OF edgeDetector IS
+  
+  SIGNAL pulse_delayed : std_ulogic;
+  SIGNAL rising_detected_s : std_ulogic;
+  SIGNAL falling_detected_s : std_ulogic;
+
+BEGIN
+
+  -- delay pulse
+  reg : PROCESS (reset, clock)
+  BEGIN
+    IF reset = '1' THEN
+      pulse_delayed <= '0';
+    ELSIF rising_edge(clock) THEN
+      pulse_delayed <= pulse;  
+    END IF;    
+  END PROCESS reg ;
+  
+  -- edge detection
+  rising <= '1' when (pulse = '1') and (pulse_delayed = '0')
+    else '0'; 
+  falling <= '1' when (pulse = '0') and (pulse_delayed = '1')
+    else '0'; 
+  
+END ARCHITECTURE RTL;