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[/] [open8_urisc/] [trunk/] [VHDL/] [o8_hd44780_8b.vhd] - Rev 217
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-- Copyright (c)2013, 2020 Jeremy Seth Henry -- All rights reserved. -- -- Redistribution and use in source and binary forms, with or without -- modification, are permitted provided that the following conditions are met: -- * Redistributions of source code must retain the above copyright -- notice, this list of conditions and the following disclaimer. -- * Redistributions in binary form must reproduce the above copyright -- notice, this list of conditions and the following disclaimer in the -- documentation and/or other materials provided with the distribution, -- where applicable (as part of a user interface, debugging port, etc.) -- -- THIS SOFTWARE IS PROVIDED BY JEREMY SETH HENRY ``AS IS'' AND ANY -- EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED -- WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE -- DISCLAIMED. IN NO EVENT SHALL JEREMY SETH HENRY BE LIABLE FOR ANY -- DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES -- (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; -- LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND -- ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT -- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF -- THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -- -- VHDL Entity: o8_hd44780_8b -- Description: Provides low-level access to a "standard" character LCD using -- the ST/HD44780(U) control ASIC wired in full (8-bit) mode. -- All low-level timing of the control signals are handled by -- this module, allowing client firmware to use a simple -- register interface to program the LCD panel. -- Init routine initializes the display and displays a single -- character to demonstrate correct function, then listens for -- user data on its external interface. -- -- Register Map -- Address Function -- Offset Bitfield Description Read/Write -- 0x0 AAAAAAAA LCD Register Write (Write-only) -- 0x1 AAAAAAAA LCD Data Write (Write-only) -- 0x2 AAAAAAAA LCD Contrast (Read-Write) -- 0x3 AAAAAAAA LCD Backlight (Read-Write) -- -------------------------------------------------------------------------------- -- LCD Controller -------------------------------------------------------------------------------- -- -- LCD Instruction Set -- Instruction RS RW D7 D6 D5 D4 D3 D2 D1 D0 Time ------------------------------------------------------------------------ -- Clear Display | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1.52mS -- Return Home | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | x | 1.52mS -- Entry Mode | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | ID| S | 37uS -- Display Pwr | 0 | 0 | 0 | 0 | 0 | 0 | 1 | D | C | B | 37uS -- Cursor/Display Shift | 0 | 0 | 0 | 0 | 0 | 1 | SC| RL| x | x | 37uS -- Function Set | 0 | 0 | 0 | 0 | 1 | DL| N | F | x | x | 37uS -- Set CGRAM Address | 0 | 0 | 0 | 1 | A | A | A | A | A | A | 37uS -- Set DDRAM Address | 0 | 0 | 1 | A | A | A | A | A | A | A | 37uS -- Notes: -- ID = Increment/Decrement DDRAM Address (1 = increment, 0 = decrement) -- S = Shift Enable (1 = Shift display according to ID, 0 = Don't shift) -- D = Display On/Off (1 = on, 0 = off) -- C = Cursor On/Off (1 = on, 0 = off) -- B = Cursor Blink (1 = block cursor, 0 = underline cursor) -- SC / RL = Shift Cursor/Display Right/Left (see data sheet - not needed for init) -- F = Font (0 = 5x8, 1 = 5x11) Ignored on 2-line displays (N = 1) -- N = Number of Lines (0 = 1 lines, 1 = 2 lines) -- DL = Data Length (0 = 4-bit bus, 1 = 8-bit bus) This is fixed at 1 in this module -- A = Address (see data sheet for usage) -- -- Revision History -- Author Date Change ------------------ -------- --------------------------------------------------- -- Seth Henry 01/22/13 Design Start -- Seth Henry 04/10/20 Code & comment cleanup library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; use ieee.std_logic_arith.all; library work; use work.open8_pkg.all; entity o8_hd44780_8b is generic( Use_Contrast : boolean; Default_Contrast : std_logic_vector(7 downto 0); Use_Backlight : boolean; Default_Brightness : std_logic_vector(7 downto 0); Address : ADDRESS_TYPE; Reset_Level : std_logic; Sys_Freq : real ); port( Clock : in std_logic; Reset : in std_logic; uSec_Tick : in std_logic; -- Bus_Address : in ADDRESS_TYPE; Wr_Enable : in std_logic; Wr_Data : in DATA_TYPE; Rd_Enable : in std_logic; Rd_Data : out DATA_TYPE; Interrupt : out std_logic; -- LCD_E : out std_logic; LCD_RW : out std_logic; LCD_RS : out std_logic; LCD_D : out std_logic_vector(7 downto 0); LCD_CN : out std_logic; LCD_BL : out std_logic ); end entity; architecture behave of o8_hd44780_8b is constant User_Addr : std_logic_vector(15 downto 2) := Address(15 downto 2); alias Comp_Addr is Bus_Address(15 downto 2); signal Addr_Match : std_logic := '0'; alias Reg_Addr is Bus_Address(1 downto 0); signal Reg_Addr_q : std_logic_vector(1 downto 0) := (others => '0'); signal Wr_En : std_logic := '0'; signal Wr_Data_q : DATA_TYPE := x"00"; signal Rd_En : std_logic := '0'; signal Reg_Valid : std_logic := '0'; signal Reg_Sel : std_logic := '0'; signal Reg_Data : DATA_TYPE := x"00"; signal Tx_Ready : std_logic := '0'; constant LCD_CONFIG1 : std_logic_vector(7 downto 0) := x"38"; -- Set 4-bit, 2-line mode constant LCD_CONFIG2 : std_logic_vector(7 downto 0) := x"0C"; -- Turn display on, no cursor constant LCD_CONFIG3 : std_logic_vector(7 downto 0) := x"01"; -- Clear display constant LCD_CONFIG4 : std_logic_vector(7 downto 0) := x"06"; -- Positive increment, no shift constant LCD_CONFIG5 : std_logic_vector(7 downto 0) := x"2A"; -- Print a "*" constant LCD_CONFIG6 : std_logic_vector(7 downto 0) := x"02"; -- Reset the cursor signal init_count : std_logic_vector(2 downto 0) := (others => '0'); constant INIT_40MS : integer := 40000; constant INIT_BITS : integer := ceil_log2(INIT_40MS); constant INIT_DELAY : std_logic_vector(INIT_BITS-1 downto 0) := conv_std_logic_vector(INIT_40MS,INIT_BITS); -- For "long" instructions, such as clear display and return home, we need to wait for more -- than 1.52mS. Experimentally, 2mS seems to work ideally, and for init this isn't an issue constant CLDSP_2MS : integer := 2000; constant CLDSP_DELAY : std_logic_vector(INIT_BITS-1 downto 0) := conv_std_logic_vector(CLDSP_2MS,INIT_BITS); -- For some reason, we are required to wait 80uS before checking the busy flag, despite -- most instructions completing in 37uS. No clue as to why, but it works constant BUSY_50US : integer := 50; constant BUSY_DELAY : std_logic_vector(INIT_BITS-1 downto 0) := conv_std_logic_vector(BUSY_50US-1, INIT_BITS); signal busy_timer : std_logic_vector(INIT_BITS-1 downto 0) := (others => '0'); constant SNH_600NS : integer := integer(Sys_Freq * 0.000000600); constant SNH_BITS : integer := ceil_log2(SNH_600NS); constant SNH_DELAY : std_logic_vector(SNH_BITS-1 downto 0) := conv_std_logic_vector(SNH_600NS-1, SNH_BITS); signal io_timer : std_logic_vector(SNH_BITS - 1 downto 0) := (others => '0'); type IO_STATES is (INIT, FN_JUMP, IDLE, WR_PREP, WR_SETUP, WR_HOLD, BUSY_PREP, BUSY_WAIT, ISSUE_INT ); signal io_state : IO_STATES; signal LCD_Data : DATA_TYPE := x"00"; signal LCD_Addr : std_logic := '0'; -------------------------------------------------------------------------------- -- Backlight & Contrast signals -------------------------------------------------------------------------------- signal LCD_Contrast : DATA_TYPE := x"00"; signal LCD_Bright : DATA_TYPE := x"00"; begin -------------------------------------------------------------------------------- -- Open8 Register interface -------------------------------------------------------------------------------- Addr_Match <= '1' when Comp_Addr = User_Addr else '0'; io_reg: process( Clock, Reset ) begin if( Reset = Reset_Level )then Reg_Addr_q <= (others => '0'); Wr_Data_q <= (others => '0'); Wr_En <= '0'; Rd_En <= '0'; Rd_Data <= OPEN8_NULLBUS; Reg_Valid <= '0'; Reg_Sel <= '0'; Reg_Data <= x"00"; LCD_Contrast <= Default_Contrast; LCD_Bright <= Default_Brightness; elsif( rising_edge( Clock ) )then Reg_Addr_q <= Reg_Addr; Wr_Data_q <= Wr_Data; Wr_En <= Addr_Match and Wr_Enable; Reg_Valid <= '0'; if( Wr_En = '1' )then case( Reg_Addr_q )is when "00" | "01" => Reg_Valid <= '1'; Reg_Sel <= Reg_Addr_q(0); Reg_Data <= Wr_Data_q; when "10" => LCD_Contrast <= Wr_Data_q; when "11" => LCD_Bright <= Wr_Data_q; when others => null; end case; end if; Rd_Data <= OPEN8_NULLBUS; Rd_En <= Addr_Match and Rd_Enable; if( Rd_En = '1' )then case( Reg_Addr_q )is when "00" | "01" => Rd_Data(7) <= Tx_Ready; when "10" => Rd_Data <= LCD_Contrast; when "11" => Rd_Data <= LCD_Bright; when others => null; end case; end if; end if; end process; -------------------------------------------------------------------------------- -- LCD and Register logic -------------------------------------------------------------------------------- LCD_RW <= '0'; -- Permanently wire the RW line low LCD_IO: process( Clock, Reset ) begin if( Reset = Reset_Level )then io_state <= INIT; init_count <= (others => '0'); io_timer <= (others => '0'); busy_timer <= (others => '0'); LCD_Data <= (others => '0'); LCD_Addr <= '0'; LCD_E <= '0'; LCD_RS <= '0'; LCD_D <= (others => '0'); Tx_Ready <= '0'; Interrupt <= '0'; elsif( rising_edge(Clock) )then LCD_E <= '0'; LCD_RS <= '0'; LCD_D <= (others => '0'); Tx_Ready <= '0'; Interrupt <= '0'; io_timer <= io_timer - 1; busy_timer <= busy_timer - uSec_Tick; case( io_state )is when INIT => busy_timer <= INIT_DELAY; init_count <= (others => '1'); io_state <= BUSY_WAIT; when FN_JUMP => io_state <= WR_PREP; case( init_count )is when "000" => io_state <= IDLE; when "001" => LCD_Addr <= '0'; LCD_Data <= LCD_CONFIG6; -- Reset the Cursor when "010" => LCD_Addr <= '1'; -- Print a "*", and LCD_Data <= LCD_CONFIG5; -- set RS to 1 when "011" => LCD_Data <= LCD_CONFIG4; -- Entry mode when "100" => LCD_Data <= LCD_CONFIG3; -- Clear Display when "101" => LCD_Data <= LCD_CONFIG2; -- Display control when "110" | "111" => LCD_Addr <= '0'; LCD_Data <= LCD_CONFIG1; -- Function set when others => null; end case; when IDLE => Tx_Ready <= '1'; if( Reg_Valid = '1' )then LCD_Addr <= Reg_Sel; LCD_Data <= Reg_Data; io_state <= WR_PREP; end if; when WR_PREP => io_timer <= SNH_DELAY; io_state <= WR_SETUP; when WR_SETUP => LCD_RS <= LCD_Addr; LCD_D <= LCD_Data; LCD_E <= '1'; if( io_timer = 0 )then io_timer <= SNH_DELAY; io_state <= WR_HOLD; end if; when WR_HOLD => LCD_RS <= LCD_Addr; LCD_D <= LCD_Data; if( io_timer = 0 )then LCD_E <= '0'; io_state <= BUSY_PREP; end if; when BUSY_PREP => busy_timer <= BUSY_DELAY; if( LCD_Addr = '0' and LCD_Data < 4 )then busy_timer <= CLDSP_DELAY; end if; io_state <= BUSY_WAIT; when BUSY_WAIT => if( busy_timer = 0 )then io_state <= ISSUE_INT; if( init_count > 0 )then init_count <= init_count - 1; io_state <= FN_JUMP; end if; end if; when ISSUE_INT => Interrupt <= '1'; io_state <= IDLE; when others => null; end case; end if; end process; -------------------------------------------------------------------------------- -- Contrast control logic (optional) -------------------------------------------------------------------------------- Contrast_Disabled: if( not Use_Contrast )generate LCD_CN <= '0'; end generate; Contrast_Enabled: if( Use_Contrast )generate U_CN : entity work.vdsm8 generic map( Reset_Level => Reset_Level ) port map( Clock => Clock, Reset => Reset, DACin => LCD_Contrast, DACout => LCD_CN ); end generate; -------------------------------------------------------------------------------- -- Backlight control logic (optional) -------------------------------------------------------------------------------- Backlight_Disabled: if( not Use_Backlight )generate LCD_BL <= '0'; end generate; Backlight_Enabled: if( Use_Backlight )generate U_BL : entity work.vdsm8 generic map( Reset_Level => Reset_Level ) port map( Clock => Clock, Reset => Reset, DACin => LCD_Bright, DACout => LCD_BL ); end generate; end architecture;
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