add silence detection

1 files changed, 54 insertions, 0 deletions

diff --git a/silence_detector.vhd b/silence_detector.vhd
new file mode 100644
index 0000000..fe85824
--- /dev/null
+++ b/silence_detector.vhd
@@ -0,0 +1,54 @@
+
+
+library IEEE;
+use IEEE.STD_LOGIC_1164.all;
+use IEEE.std_logic_unsigned.all;
+use IEEE.numeric_std.all;
+
+entity silence_detector is
+    port
+        (
+            max_ticks : in  integer;
+            clk       : in  std_logic;
+            d         : in  std_logic_vector(23 downto 0);
+            n_reset   : in  std_logic;
+            silent    : out std_logic
+            );
+end silence_detector;
+
+
+architecture rtl of silence_detector is
+
+    signal ticks      : std_logic_vector (31 downto 0);
+    signal last_d     : std_logic_vector (23 downto 0);
+    signal silent_buf : std_logic;
+
+begin
+
+    process (last_d, d, clk, max_ticks, ticks)
+    begin
+        if n_reset = '0' then
+            ticks      <= (others => '0');
+            silent_buf <= '0';
+            last_d     <= (others => '0');
+        elsif rising_edge(clk) then
+            last_d <= d;
+
+            if last_d = d then
+                if ticks < max_ticks then
+                    ticks <= ticks +1;
+                else
+                    silent_buf <= '1';
+                end if;
+            else
+                ticks      <= (others => '0');
+                silent_buf <= '0';
+            end if;
+        end if;
+    end process;
+
+
+    silent <= silent_buf;
+
+end rtl;
+