From a8dc43023e724bb1ad7ec721ed981070f270eda6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mario=20H=C3=BCttel?= <shino@shimatta.de>
Date: Tue, 21 Nov 2017 22:48:05 +0100
Subject: [PATCH] added synchronizer ip for UART, wrote reset detection

---
 synchronizer.vhd | 31 ++++++++++++++++++
 top.vhd          | 81 ++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 109 insertions(+), 3 deletions(-)
 create mode 100644 synchronizer.vhd

diff --git a/synchronizer.vhd b/synchronizer.vhd
new file mode 100644
index 0000000..3630ae0
--- /dev/null
+++ b/synchronizer.vhd
@@ -0,0 +1,31 @@
+library ieee;
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+
+entity synchronizer is
+	generic(COUNT : integer := 1);
+	port(
+		clk  : in  std_logic;
+		rst  : in  std_logic;
+		dIn  : in  std_logic_vector(COUNT - 1 downto 0);
+		dOut : out std_logic_vector(COUNT - 1 downto 0)
+	);
+end entity synchronizer;
+
+architecture RTL of synchronizer is
+	signal temp : std_logic_vector(COUNT - 1 downto 0);
+begin
+	synch : process(rst, clk) is
+	begin
+		for i in 0 to COUNT - 1 loop
+			if rst = '1' then
+				temp(i) <= '0';
+				dOut(i)  <= '0';
+			elsif rising_edge(clk) then
+				temp(i) <= dIn(i);
+				dOut(i) <= temp(i);
+			end if;
+		end loop;
+	end process synch;
+
+end architecture RTL;
diff --git a/top.vhd b/top.vhd
index ba3ec0b..478a1b2 100644
--- a/top.vhd
+++ b/top.vhd
@@ -23,11 +23,12 @@ use ieee.numeric_std.all;
 entity config_top is
 
   generic (
-    BAUD_RATE : integer := 9600);
+    CLKDIV : integer := 10);
 
   port (
     clk     : in  std_logic;            -- input clock 12 MHz
     dts     : in  std_logic;            -- DTS Strobe signal
+    rst_out : out std_logic;
     uart_tx : out std_logic;            -- UART TX
     uart_rx : in  std_logic);           -- UART RX
 
@@ -35,11 +36,85 @@ end entity config_top;
 
 
 architecture RTL of config_top is
+  ----------------- RESET LOGIC ------------------------------
+  signal dts_sync      : std_logic_vector(2 downto 0) := (others => '0');
+  signal rst           : std_logic;     -- reset (high active)
+  ----------------- UART RX ----------------------------------
+  signal data_rx       : std_logic_vector(7 downto 0);
+  signal byte_ready_rx : std_logic;
+  signal error_rx      : std_logic;
+  ----------------- UART TX ----------------------------------
+  signal data_tx       : std_logic_vector(7 downto 0);
+  signal byte_ready_tx : std_logic;
+  signal busy_tx       : std_logic;
+
+
+  signal config_busy : std_logic := '1';  -- indicates that the core is in configuration/waiting mode
+  -- and the user logic has to stay in reset
 
 begin  -- architecture RTL
 
-  
 
-  
+  uart_rx_1 : entity work.uart_rx
+    port map (
+      clk          => clk,
+      rst          => rst,
+      data         => data_rx,
+      byte_ready   => byte_ready_rx,
+      error        => error_rx,
+      ckDiv        => CLKDIV,
+      parityEnable => '1',
+      parityOdd    => '0',
+      twoStopBits  => '0',
+      rx           => uart_rx);
+
+  uart_tx_1 : entity work.uart_tx
+    port map (
+      clk          => clk,
+      rst          => rst,
+      data         => data_tx,
+      byte_ready   => byte_ready_tx,
+      busy         => busy_tx,
+      ckDiv        => CLKDIV,
+      parityEnable => '1',
+      parityOdd    => '0',
+      twoStopBits  => '0',
+      tx           => uart_tx);
+
+
+  timeout_counter_gen : process(clk) is
+    variable cnt : integer range 0 to 40000;
+  begin
+  -- TODO: implement timeout counter
+  end process timeout_counter_gen;
+
+
+  -- Generate reset pulse on rising edge of dts input
+  reset_gen : process(clk) is
+  begin
+    if rising_edge(clk) then
+      rst      <= '0';
+      dts_sync <= dts_sync(1 downto 0) & dts;  -- Shif register (sync and edge detect)
+      if (dts_sync(2 downto 1) = "01") then    -- rising edge of DTS
+        rst <= '1';
+      end if;
+    end if;
+  end process reset_gen;
+
+
+  -- hold user logic in reset until config finished or timeout
+  user_logic_reset_gen : process(clk, rst) is
+  begin
+    if rst = '1' then
+      rst_out <= '1';
+    elsif rising_edge(clk) then
+      if config_busy = '0' then
+        rst_out <= '0';
+      end if;
+    end if;
+  end process user_logic_reset_gen;
+
+
+  ------ Asynchronous output assignments ---------------
 
 end architecture RTL;