Add basic example image generator

image_generator.vhd

@@ -0,0 +1,82 @@
+library ieee;
+
+use ieee.std_logic_1164.all;
+use ieee.std_logic_unsigned.all;
+use ieee.numeric_std.all;
+
+entity image_generator is
+    generic (
+        input_clk: integer
+    );
+    port (
+        clk: in std_logic;
+        x, y: in std_logic_vector(9 downto 0);
+        ctrl_up: in std_logic;
+        ctrl_down: in std_logic;
+
+        rgb: out std_logic_vector(23 downto 0)
+    );
+end image_generator;
+
+
+architecture logic of image_generator is
+    type glyph is array(0 to 7) of std_logic_vector(7 downto 0);
+    constant emoji_grin: glyph := (
+        "00111100",
+        "01000010",
+        "10101001",
+        "10101001",
+        "10000101",
+        "10111001",
+        "01000010",
+        "00111100"
+    );
+
+    signal glyph_x: integer range 0 to 7;
+    signal glyph_y: integer range 0 to 7;
+
+    signal color: std_logic_vector(23 downto 0);
+    signal color_index: integer range 0 to 2;
+begin
+    glyph_x <= to_integer(unsigned(x(4 downto 1)));
+    glyph_y <= to_integer(unsigned(y(4 downto 1)));
+
+    process(clk) is
+        variable last_up: std_logic;
+        variable last_down: std_logic;
+        constant debounce_max: integer := input_clk / 50; -- 20ms
+        variable debounce: integer range 0 to debounce_max := 0;
+    begin
+        if rising_edge(clk) then
+            if debounce = 0 then
+                if ctrl_up = '1' and last_up = '0' then
+                    if color_index /= 2 then
+                        color_index <= color_index + 1;
+                    end if;
+                    debounce := debounce_max;
+                end if;
+                last_up := ctrl_up;
+
+                if ctrl_down = '1' and last_down = '0' then
+                    if color_index /= 0 then
+                        color_index <= color_index - 1;
+                    end if;
+                    debounce := debounce_max;
+                end if;
+                last_down := ctrl_down;
+            else
+                debounce := debounce - 1;
+            end if;
+        end if;
+    end process;
+
+    with color_index select color <=
+        "111111111111111111111111" when 0,
+        "000000000000000011111111" when 1,
+        "000101001111111110110100" when 2;
+
+    -- actually currently BRG
+    rgb <=
+        color when x(4) = y(4) and emoji_grin(glyph_y)(glyph_x) = '1' else
+        "000000000000000000000000";
+end logic;

main.ucf

@@ -24,6 +24,9 @@ NET "clk" LOC = AH15;
 NET "clk" PERIOD = 100 MHz HIGH 50%;
 
 NET "switch_center" LOC = AJ6;
+NET "rotary_up" LOC = AH30;
+NET "rotary_down" LOC = AG30;
+NET "rotary_push" LOC = AH29;
 
 NET "led0" LOC = H18;
 NET "led1" LOC = L18;

main.vhd

@@ -4,7 +4,7 @@ library unisim;
 use ieee.std_logic_1164.all;
 use ieee.std_logic_unsigned.all;
 use ieee.numeric_std.all;
--- Xilinx primitives (OBUFDS)
+-- Xilinx primitives (obufds)
 use unisim.VComponents.all;
 
 entity main is
@@ -22,6 +22,10 @@ entity main is
         i2c_sda: inout std_logic;
 
         switch_center: in std_logic;
+        rotary_up: in std_logic;
+        rotary_down: in std_logic;
+        rotary_push: in std_logic;
+
         led0: out std_logic;
         led1: out std_logic;
         led2: out std_logic;
@@ -31,7 +35,9 @@ end main;
 
 architecture Behavioral of main is
     signal clk_vga: std_logic;
-    signal pixel_rgb: std_logic_vector(23 downto 0) := "111111110000000011111111";
+    signal image_x: std_logic_vector(9 downto 0);
+    signal image_y: std_logic_vector(9 downto 0);
+    signal pixel_rgb: std_logic_vector(23 downto 0);
     signal dvi_clk: std_logic; -- connect vga_sync to dvi_clk_ds
     -- tmp
     signal hsync: std_logic;
@@ -44,8 +50,7 @@ begin
 		CLKFX_OUT => clk_vga
 	);
 
-    dvi_clk_ds: OBUFDS
-    port map(
+    dvi_clk_ds: obufds port map (
         O => dvi_clk_p,
         OB => dvi_clk_n,
         I => clk_vga
@@ -65,7 +70,8 @@ begin
 
     vga_sync: entity work.vga port map (
         clk => clk_vga,
-        --x, y (static color for now)
+        x => image_x,
+        y => image_y,
         pixel_rgb => pixel_rgb,
         dvi_d => dvi_d,
         dvi_clk => dvi_clk,
@@ -74,6 +80,17 @@ begin
         dvi_de => de
     );
 
+    image_generator_i: entity work.image_generator generic map (
+        input_clk => 48_000_000
+    ) port map (
+        clk => clk_vga,
+        x => image_x,
+        y => image_y,
+        ctrl_up => rotary_up,
+        ctrl_down => rotary_down,
+        rgb => pixel_rgb
+    );
+
     dvi_hsync <= hsync;
     dvi_vsync <= vsync;
     dvi_de <= de;