PPU AUX memory finished and tested

4 files changed, 154 insertions, 2 deletions

diff --git a/basys3/basys3.srcs/er_ram.vhd b/basys3/basys3.srcs/er_ram.vhd
index a35514c..f106d4e 100644
--- a/basys3/basys3.srcs/er_ram.vhd
+++ b/basys3/basys3.srcs/er_ram.vhd
@@ -15,7 +15,7 @@ entity er_ram is -- exposed register RAM
 		WEN : in std_logic; -- write enable
 		ADDR : in std_logic_vector(ADDR_W-1 downto 0); -- address line
 		DATA : in std_logic_vector(DATA_W-1 downto 0); -- data input
-		REG : out std_logic_vector((ADDR_W*DATA_W)-1 downto 0)); -- exposed register output
+		REG : out std_logic_vector((ADDR_RANGE*DATA_W)-1 downto 0)); -- exposed register output
 end er_ram;
 
 architecture Behavioral of er_ram is
diff --git a/basys3/basys3.srcs/ppu_aux.vhd b/basys3/basys3.srcs/ppu_aux.vhd
new file mode 100644
index 0000000..9062bc4
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_aux.vhd
@@ -0,0 +1,52 @@
+library ieee;
+library work;
+use ieee.std_logic_1164.all;
+--use ieee.numeric_std.all;
+use work.ppu_consts.all;
+
+entity ppu_aux is port(
+	CLK : in std_logic; -- system clock
+	RESET : in std_logic; -- reset memory
+
+	-- internal memory block (AUX)
+	AUX_WEN : in std_logic; -- VRAM AUX write enable
+	AUX_ADDR : in std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0); -- VRAM AUX address
+	AUX_DATA : in std_logic_vector(PPU_AUX_DATA_WIDTH-1 downto 0); -- VRAM AUX data
+	
+	-- aux outputs
+	BG_SHIFT_X : out std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
+	BG_SHIFT_Y : out std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
+	FG_FETCH : out std_logic);
+end ppu_aux;
+
+architecture Behavioral of ppu_aux is
+	component er_ram
+		generic(
+			ADDR_W : natural := PPU_AUX_ADDR_WIDTH; -- ADDR line width
+			DATA_W : natural := PPU_AUX_DATA_WIDTH; -- DATA line width
+			ADDR_LOW : natural := 16#0000#; -- starting address
+			ADDR_RANGE : natural := 16#0002#); -- amount of valid addresses after ADDR_LOW
+		port(
+			CLK : in std_logic; -- clock
+			RST : in std_logic; -- async memory clear
+			WEN : in std_logic; -- write enable
+			ADDR : in std_logic_vector(ADDR_W-1 downto 0);
+			DATA : in std_logic_vector(DATA_W-1 downto 0);
+			REG : out std_logic_vector((ADDR_RANGE*DATA_W)-1 downto 0)); -- exposed register output
+	end component;
+
+	signal INT_REG : std_logic_vector(2 * PPU_AUX_DATA_WIDTH - 1 downto 0);
+begin
+	-- docs/architecture.md#auxiliary-memory
+	FG_FETCH <= INT_REG(17);
+	BG_SHIFT_X <= INT_REG(16 downto 8);
+	BG_SHIFT_Y <= INT_REG(7 downto 0);
+
+	RAM : component er_ram port map(
+		CLK => CLK,
+		RST => RESET,
+		WEN => AUX_WEN,
+		ADDR => AUX_ADDR,
+		DATA => AUX_DATA,
+		REG => INT_REG);
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_aux_tb.vhd b/basys3/basys3.srcs/ppu_aux_tb.vhd
new file mode 100644
index 0000000..ab3db62
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_aux_tb.vhd
@@ -0,0 +1,100 @@
+library ieee;
+library unisim;
+library work;
+
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+use unisim.vcomponents.all;
+use work.ppu_consts.all;
+
+entity ppu_aux_tb is
+end ppu_aux_tb;
+
+architecture behavioral of ppu_aux_tb is
+	component ppu_aux port(
+		CLK : in std_logic; -- system clock
+		RESET : in std_logic; -- reset memory
+
+		-- internal memory block (AUX)
+		AUX_WEN : in std_logic; -- VRAM AUX write enable
+		AUX_ADDR : in std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0); -- VRAM AUX address
+		AUX_DATA : in std_logic_vector(PPU_AUX_DATA_WIDTH-1 downto 0); -- VRAM AUX data
+		
+		-- aux outputs
+		BG_SHIFT_X : out std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
+		BG_SHIFT_Y : out std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
+		FG_FETCH : out std_logic);
+	end component;
+
+	signal CLK, RST, WEN : std_logic := '0';
+	signal ADDR : std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0) := (others => '0');
+	signal DATA : std_logic_vector(PPU_AUX_DATA_WIDTH-1 downto 0) := (others => '0');
+
+	signal BG_SHIFT_X : std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
+	signal BG_SHIFT_Y : std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
+	signal FG_FETCH : std_logic;
+begin
+	uut : component ppu_aux
+		port map(
+			CLK => CLK,
+			RESET => RST,
+			AUX_WEN => WEN,
+			AUX_ADDR => ADDR,
+			AUX_DATA => DATA,
+			BG_SHIFT_X => BG_SHIFT_X,
+			BG_SHIFT_Y => BG_SHIFT_Y,
+			FG_FETCH => FG_FETCH);
+
+	tb : process
+	begin
+		-- reset
+		RST <= '1';
+		wait for 5 ns;
+		RST <= '0';
+		wait for 5 ns;
+
+		WEN <= '1';
+		-- set BG_SHIFT_X to 178
+		-- set BG_SHIFT_Y to 39
+		-- set FG_FETCH to 1
+		ADDR(0) <= '0';
+		DATA <= x"b327";
+
+		CLK <= '1';
+		wait for 1 ns;
+		CLK <= '0';
+		wait for 1 ns;
+
+		ADDR(0) <= '1';
+		DATA <= x"0002";
+
+		CLK <= '1';
+		wait for 1 ns;
+		CLK <= '0';
+		wait for 1 ns;
+
+		wait for 5 ns;
+
+		-- set BG_SHIFT_X to 30
+		-- set BG_SHIFT_Y to 69
+		-- set FG_FETCH to 0
+		ADDR(0) <= '0';
+		DATA <= x"1e45";
+
+		CLK <= '1';
+		wait for 1 ns;
+		CLK <= '0';
+		wait for 1 ns;
+
+		ADDR(0) <= '1';
+		DATA <= x"0000";
+
+		CLK <= '1';
+		wait for 1 ns;
+		CLK <= '0';
+		wait for 1 ns;
+
+
+		wait; -- stop for simulator
+	end process;
+end;
diff --git a/basys3/basys3.srcs/ppu_consts.vhd b/basys3/basys3.srcs/ppu_consts.vhd
index 3e7d46d..ab2ccf1 100644
--- a/basys3/basys3.srcs/ppu_consts.vhd
+++ b/basys3/basys3.srcs/ppu_consts.vhd
@@ -14,7 +14,7 @@ package ppu_consts is
 	constant PPU_FAM_DATA_WIDTH : natural := 16;
 	constant PPU_PAL_ADDR_WIDTH : natural := 6;
 	constant PPU_PAL_DATA_WIDTH : natural := 12;
-	constant PPU_AUX_ADDR_WIDTH : natural := 2;
+	constant PPU_AUX_ADDR_WIDTH : natural := 1;
 	constant PPU_AUX_DATA_WIDTH : natural := 16;
 	constant PPU_POS_H_WIDTH : natural := 9; -- amount of bits for horizontal screen offset
 	constant PPU_POS_V_WIDTH : natural := 8; -- amount of bits for vertical screen offset