Update .gitignore and enhance README.md; add new VHDL files for KittCarPWM, ShiftRegisters, and PulseWidthModulator

LAB1/src/KittCar.vhd

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+-- File:            KittCar_v1.vhd
+-- Description:     Better asyncronous logic handling & unsigned n_period
+-- Known problem:   Not yet tested
+
+---------- DEFAULT LIBRARY ---------
+LIBRARY IEEE;
+USE IEEE.STD_LOGIC_1164.ALL;
+USE IEEE.NUMERIC_STD.ALL;
+------------------------------------
+
+ENTITY KittCar IS
+    GENERIC (
+
+        CLK_PERIOD_NS : POSITIVE RANGE 1 TO 100 := 10; -- clk period in nanoseconds
+        MIN_KITT_CAR_STEP_MS : POSITIVE RANGE 1 TO 2000 := 1; -- Minimum step period in milliseconds (i.e., value in milliseconds of Delta_t)
+
+        NUM_OF_SWS : INTEGER RANGE 1 TO 16 := 16; -- Number of input switches
+        NUM_OF_LEDS : INTEGER RANGE 1 TO 16 := 16 -- Number of output LEDs
+
+    );
+    PORT (
+
+        ------- Reset/Clock --------
+        reset : IN STD_LOGIC;
+        clk : IN STD_LOGIC;
+        ----------------------------
+
+        -------- LEDs/SWs ----------
+        sw : IN STD_LOGIC_VECTOR(NUM_OF_SWS - 1 DOWNTO 0); -- Switches avaiable on Basys3
+        led : OUT STD_LOGIC_VECTOR(NUM_OF_LEDS - 1 DOWNTO 0) -- LEDs avaiable on Basys3
+        ----------------------------
+
+    );
+END KittCar;
+
+ARCHITECTURE Behavioral OF KittCar IS
+    CONSTANT MIN_KITT_CAR_STEP_NS : UNSIGNED(46 DOWNTO 0) := to_unsigned(MIN_KITT_CAR_STEP_MS * 1000000, 47);
+
+    SIGNAL leds_sr : STD_LOGIC_VECTOR(led'RANGE) := (OTHERS => '0');
+    SIGNAL n_period : UNSIGNED(sw'RANGE) := to_unsigned(1, sw'LENGTH);
+    SIGNAL up : STD_LOGIC := '1';
+BEGIN
+
+    -- Sincronous logic
+    PROCESS (clk, reset)
+        VARIABLE counter : UNSIGNED(46 DOWNTO 0) := (OTHERS => '0');
+    BEGIN
+        IF reset = '1' THEN
+            leds_sr <= (OTHERS => '0');
+            counter := (OTHERS => '0');
+        ELSIF rising_edge(clk) THEN
+
+            -- Kitt logic
+            IF unsigned(leds_sr) = 0 THEN
+                leds_sr(0) <= '1';
+                up <= '1';
+            ELSIF leds_sr(led'HIGH) = '1' THEN
+                up <= '0';
+            ELSIF leds_sr(led'LOW) = '1' THEN
+                up <= '1';
+            END IF;
+
+            -- Increment the counter
+            counter := counter + to_unsigned(CLK_PERIOD_NS, counter'LENGTH);
+
+            -- Calculate the number of periods
+            IF counter >= (MIN_KITT_CAR_STEP_NS * n_period) THEN
+
+                -- Shift the leds
+                IF up = '1' THEN
+                    leds_sr <= leds_sr(NUM_OF_LEDS - 2 DOWNTO 0) & '0';
+                ELSIF up = '0' THEN
+                    leds_sr <= '0' & leds_sr(NUM_OF_LEDS - 1 DOWNTO 1);
+                END IF;
+
+                -- Reset the counter
+                counter := (OTHERS => '0');
+            END IF;
+        END IF;
+    END PROCESS;
+
+    -- Handle the switch
+    PROCESS (sw)
+    BEGIN
+        n_period <= unsigned(sw) + 1;
+    END PROCESS;
+
+    led <= leds_sr;
+
+END Behavioral;