Subversion Repositories vga_lcd

--

-- File pgen.vhd, Video Pixel Generator

-- Project: VGA

-- Author : Richard Herveille

-- rev.: 0.1 April 19th, 2001. Initial release

-- rev.: 1.0 July  15th, 2001. Removed synchronized registers; static settings don't require synchronization.

--

--

library ieee;

use ieee.std_logic_1164.all;

use ieee.std_logic_arith.all;

entity Pgen is

        port(

                mclk : in std_logic;                        -- master clock

                pclk : in std_logic;                        -- pixel clock

                ctrl_Ven : in std_logic;                    -- VideoEnable signal

                -- horizontal timing settings

                ctrl_HSyncL : in std_logic;                 -- horizontal sync pulse polarization level (pos/neg)

                Thsync : in unsigned(7 downto 0);           -- horizontal sync pulse width (in pixels)

                Thgdel : in unsigned(7 downto 0);           -- horizontal gate delay (in pixels)

                Thgate : in unsigned(15 downto 0);          -- horizontal gate (number of visible pixels per line)

                Thlen  : in unsigned(15 downto 0);          -- horizontal length (number of pixels per line)

                -- vertical timing settings

                ctrl_VSyncL : in std_logic;                 -- vertical sync pulse polarization level (pos/neg)

                Tvsync : in unsigned(7 downto 0);           -- vertical sync width (in lines)

                Tvgdel : in unsigned(7 downto 0);           -- vertical gate delay (in lines)

                Tvgate : in unsigned(15 downto 0);          -- vertical gate (visible number of lines in frame)

                Tvlen  : in unsigned(15 downto 0);          -- vertical length (number of lines in frame)

                ctrl_CSyncL : in std_logic;                 -- composite sync pulse polarization level

                ctrl_BlankL : in std_logic;                 -- blank signal polarization level

                -- status outputs

                eoh,                                        -- end of horizontal

                eov,                                        -- end of vertical

                Gate : out std_logic;                       -- vertical AND horizontal gate (logical AND function)

                -- pixel control outputs

                Hsync,                                      -- horizontal sync pulse

                Vsync,                                      -- vertical sync pulse

                Csync,                                      -- composite sync: Hsync OR Vsync (logical OR function)

                Blank : out std_logic                       -- blank signals

        );

end entity Pgen;

architecture dataflow of Pgen is

        --

        -- Component declarations

        --

        component tgen is

        port(

                clk : in std_logic;

                rst : in std_logic;

                -- horizontal timing settings

                HSyncL : in std_logic;              -- horizontal sync pulse polarization level (pos/neg)

                Thsync : in unsigned(7 downto 0);   -- horizontal sync pulse width (in pixels)

                Thgdel : in unsigned(7 downto 0);   -- horizontal gate delay (in pixels)

                Thgate : in unsigned(15 downto 0);  -- horizontal gate (number of visible pixels per line)

                Thlen  : in unsigned(15 downto 0);  -- horizontal length (number of pixels per line)

                -- vertical timing settings

                VSyncL : in std_logic;              -- vertical sync pulse polarization level (pos/neg)

                Tvsync : in unsigned(7 downto 0);   -- vertical sync width (in lines)

                Tvgdel : in unsigned(7 downto 0);   -- vertical gate delay (in lines)

                Tvgate : in unsigned(15 downto 0);  -- vertical gate (visible number of lines in frame)

                Tvlen  : in unsigned(15 downto 0);  -- vertical length (number of lines in frame)

                CSyncL : in std_logic;              -- composite sync pulse polarization level (pos/neg)

                BlankL : in std_logic;              -- blank signal polarization level

                eol,                                -- end of line

                eof,                                -- end of frame

                gate,                               -- vertical AND horizontal gate (logical and function)

                Hsync,                              -- horizontal sync pulse

                Vsync,                              -- vertical sync pulse

                Csync,                              -- composite sync pulse

                Blank : out std_logic               -- blank signal

        );

        end component tgen;

        --

        -- signals

        --

        signal eol, eof : std_logic;

begin

        --

        -- timing block

        --

        tblk: block

                signal nVen : std_logic;                 -- video enable signal (active low)

        begin

                -- synchronize timing/control settings (from master-clock-domain to pixel-clock-domain)

                sync_settings: process(pclk)

                begin

                        if (pclk'event and pclk = '1') then

                                nVen    <= not ctrl_Ven;

                        end if;

                end process sync_settings;

                -- hookup video timing generator

                vtgen: tgen port map (clk => pclk, rst => nVen, HSyncL => ctrl_HSyncL, Thsync => Thsync, Thgdel => Thgdel, Thgate => Thgate, Thlen => Thlen,

                                                                                VsyncL => ctrl_VsyncL, Tvsync => Tvsync, Tvgdel => Tvgdel, Tvgate => Tvgate, Tvlen => Tvlen, CSyncL => ctrl_CSyncL,

                                                                                BlankL => ctrl_BlankL, eol => eol, eof => eof, gate => gate, Hsync => Hsync, Vsync => Vsync, Csync => Csync, Blank => Blank);

        end block tblk;

        --

        -- pixel clock

        --

        pblk: block

                signal seol, seof : std_logic;           -- synchronized end-of-line, end-of-frame

                signal dseol, dseof : std_logic;         -- delayed synchronized eol, eof

        begin

                -- synchronize eol, eof (from pixel-clock-domain to master-clock-domain)

                sync_eol_eof: process(mclk)

                begin

                        if (mclk'event and mclk = '1') then

                                seol  <= eol;

                                dseol <= seol;

                                seof  <= eof;

                                dseof <= seof;

                                eoh <= seol and not dseol;

                                eov <= seof and not dseof;

                        end if;

                end process sync_eol_eof;

        end block pblk;

end architecture dataflow;