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-------------------------------------------------------------------------------------------------
-- Z80_Soc (Z80 System on Chip)
--
-- Version 0.5 Beta
--
-- Developer: Ronivon Candido Costa
-- Release Date: 2008 / 04 / 16
--
-- Based on the T80 core: http://www.opencores.org/projects.cgi/web/t80
-- This version developed and tested on: Altera DE1 Development Board
--
-- Peripherals configured (Using Ports):
--
--      08 KB Internal ROM      Read            (0x0000h - 0x1FFFh)
--      08 KB INTERNAL VRAM     Write           (0x2000h - 0x3FFFh)
--      48 KB External SRAM     Read/Write      (0x4000h - 0xFFFFh)
--      08 Green Leds           Out             (Port 0x01h)
--      08 Red Leds                     Out             (Port 0x02h)
--      04 Seven Seg displays   Out             (Ports 0x10h and 0x11h)
--      36 Pins GPIO0           In/Out  (Ports 0xA0h, 0xA1h, 0xA2h, 0xA3h, 0xA4h, 0xC0h)
--      36 Pins GPIO1           In/Out  (Ports 0xB0h, 0xB1h, 0xB2h, 0xB3h, 0xB4h, 0xC1h)
--      08 Switches                     In              (Port 0x20h)
--      04 Push buttons         In              (Port 0x30h)
--      PS/2 keyboard           In              (Port 0x80h)
--      Video Out 40x30 (VGA)   Out             (0x2000h - 0x24B0)
--
-- TO-DO:
--      - Monitor program to introduce Z80 Assmebly codes and run
--      - Serial communication, to download assembly code from PC
--      - Add hardware support for 80x40 Video out
--      - SD/MMC card interface to read/store data and programs
-------------------------------------------------------------------------------------------------
 
library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_arith.all;
use IEEE.std_logic_unsigned.all;
 
entity  TOP_DE1 is
        port(
 
    -- Clocks
    CLOCK_27,                                      -- 27 MHz
    CLOCK_50,                                      -- 50 MHz
    EXT_CLOCK : in std_logic;                      -- External Clock
 
    -- Buttons and switches
    KEY : in std_logic_vector(3 downto 0);         -- Push buttons
    SW : in std_logic_vector(9 downto 0);          -- Switches
 
    -- LED displays
    HEX0, HEX1, HEX2, HEX3                         -- 7-segment displays
                        : out std_logic_vector(6 downto 0);
    LEDG : out std_logic_vector(7 downto 0);       -- Green LEDs
    LEDR : out std_logic_vector(9 downto 0);       -- Red LEDs
 
    -- RS-232 interface
    UART_TXD : out std_logic;                      -- UART transmitter   
    UART_RXD : in std_logic;                       -- UART receiver
 
    -- IRDA interface
 
    -- IRDA_TXD : out std_logic;                      -- IRDA Transmitter
    IRDA_RXD : in std_logic;                       -- IRDA Receiver
 
    -- SDRAM
    DRAM_DQ : inout std_logic_vector(15 downto 0); -- Data Bus
    DRAM_ADDR : out std_logic_vector(11 downto 0); -- Address Bus    
    DRAM_LDQM,                                     -- Low-byte Data Mask 
    DRAM_UDQM,                                     -- High-byte Data Mask
    DRAM_WE_N,                                     -- Write Enable
    DRAM_CAS_N,                                    -- Column Address Strobe
    DRAM_RAS_N,                                    -- Row Address Strobe
    DRAM_CS_N,                                     -- Chip Select
    DRAM_BA_0,                                     -- Bank Address 0
    DRAM_BA_1,                                     -- Bank Address 0
    DRAM_CLK,                                      -- Clock
    DRAM_CKE : out std_logic;                      -- Clock Enable
 
    -- FLASH
    FL_DQ : inout std_logic_vector(7 downto 0);      -- Data bus
    FL_ADDR : out std_logic_vector(21 downto 0);     -- Address bus
    FL_WE_N,                                         -- Write Enable
    FL_RST_N,                                        -- Reset
    FL_OE_N,                                         -- Output Enable
    FL_CE_N : out std_logic;                         -- Chip Enable
 
    -- SRAM
    SRAM_DQ : inout std_logic_vector(15 downto 0); -- Data bus 16 Bits
    SRAM_ADDR : out std_logic_vector(17 downto 0); -- Address bus 18 Bits
    SRAM_UB_N,                                     -- High-byte Data Mask 
    SRAM_LB_N,                                     -- Low-byte Data Mask 
    SRAM_WE_N,                                     -- Write Enable
    SRAM_CE_N,                                     -- Chip Enable
    SRAM_OE_N : out std_logic;                     -- Output Enable
 
    -- SD card interface
    SD_DAT : in std_logic;      -- SD Card Data      SD pin 7 "DAT 0/DataOut"
    SD_DAT3 : out std_logic;    -- SD Card Data 3    SD pin 1 "DAT 3/nCS"
    SD_CMD : out std_logic;     -- SD Card Command   SD pin 2 "CMD/DataIn"
    SD_CLK : out std_logic;     -- SD Card Clock     SD pin 5 "CLK"
 
    -- USB JTAG link
    TDI,                        -- CPLD -> FPGA (data in)
    TCK,                        -- CPLD -> FPGA (clk)
    TCS : in std_logic;         -- CPLD -> FPGA (CS)
    TDO : out std_logic;        -- FPGA -> CPLD (data out)
 
    -- I2C bus
    I2C_SDAT : inout std_logic; -- I2C Data
    I2C_SCLK : out std_logic;   -- I2C Clock
 
    -- PS/2 port
    PS2_DAT,                    -- Data
    PS2_CLK : inout std_logic;     -- Clock
 
    -- VGA output
    VGA_HS,                                             -- H_SYNC
    VGA_VS : out std_logic;                             -- SYNC
    VGA_R,                                              -- Red[3:0]
    VGA_G,                                              -- Green[3:0]
    VGA_B : out std_logic_vector(3 downto 0);           -- Blue[3:0]
 
    -- Audio CODEC
    AUD_ADCLRCK : inout std_logic;                      -- ADC LR Clock
    AUD_ADCDAT : in std_logic;                          -- ADC Data
    AUD_DACLRCK : inout std_logic;                      -- DAC LR Clock
    AUD_DACDAT : out std_logic;                         -- DAC Data
    AUD_BCLK : inout std_logic;                         -- Bit-Stream Clock
    AUD_XCK : out std_logic;                            -- Chip Clock
 
    -- General-purpose I/O
    GPIO_0,                                      -- GPIO Connection 0
    GPIO_1 : inout std_logic_vector(35 downto 0) -- GPIO Connection 1    
);
end TOP_DE1;
 
architecture rtl of TOP_DE1 is
 
        component T80s
        generic(
                Mode : integer := 0);
        port (
                RESET_n         : in std_logic;
                CLK_n           : in std_logic;
                WAIT_n          : in std_logic;
                INT_n           : in std_logic;
                NMI_n           : in std_logic;
                BUSRQ_n         : in std_logic;
                M1_n            : out std_logic;
                MREQ_n          : out std_logic;
                IORQ_n          : out std_logic;
                RD_n            : out std_logic;
                WR_n            : out std_logic;
                RFSH_n          : out std_logic;
                HALT_n          : out std_logic;
                BUSAK_n         : out std_logic;
                A                       : out std_logic_vector(15 downto 0);
                DI                      : in std_logic_vector(7 downto 0);
                DO                      : out std_logic_vector(7 downto 0));
        end component;
 
        component rom
        port (
                Clk     : in std_logic;
                A       : in std_logic_vector(15 downto 0);
                D       : out std_logic_vector(7 downto 0));
        end component;
 
        component Clock_357Mhz
        PORT (
                clock_50Mhz                             : IN    STD_LOGIC;
                clock_357Mhz                    : OUT   STD_LOGIC);
        end component;
 
        component clk_div
        PORT
        (
                clock_25Mhz                             : IN    STD_LOGIC;
                clock_1MHz                              : OUT   STD_LOGIC;
                clock_100KHz                    : OUT   STD_LOGIC;
                clock_10KHz                             : OUT   STD_LOGIC;
                clock_1KHz                              : OUT   STD_LOGIC;
                clock_100Hz                             : OUT   STD_LOGIC;
                clock_10Hz                              : OUT   STD_LOGIC;
                clock_1Hz                               : OUT   STD_LOGIC);
        end component;
 
        component decoder_7seg
        port (
                NUMBER          : in   std_logic_vector(3 downto 0);
                HEX_DISP        : out  std_logic_vector(6 downto 0));
        end component;
 
        signal MREQ_n   : std_logic;
        signal IORQ_n   : std_logic;
        signal RD_n             : std_logic;
        signal WR_n             : std_logic;
        signal MWr_n    : std_logic;
        signal Rst_n_s  : std_logic;
        signal Clk_Z80  : std_logic;
        signal DI_CPU   : std_logic_vector(7 downto 0);
        signal DO_CPU   : std_logic_vector(7 downto 0);
        signal A                : std_logic_vector(15 downto 0);
        signal One              : std_logic;
 
        signal D_ROM    : std_logic_vector(7 downto 0);
 
        signal clk25mhz_sig : std_logic;
        signal clk25mhz         : std_logic;
        signal clk1hz           : std_logic;
        signal clk10hz          : std_logic;
        signal clk100hz         : std_logic;
 
        signal HEX_DISP0        : std_logic_vector(6 downto 0);
        signal HEX_DISP1        : std_logic_vector(6 downto 0);
        signal HEX_DISP2        : std_logic_vector(6 downto 0);
        signal HEX_DISP3        : std_logic_vector(6 downto 0);
 
        signal NUMBER0          : std_logic_vector(3 downto 0);
        signal NUMBER1          : std_logic_vector(3 downto 0);
        signal NUMBER2          : std_logic_vector(3 downto 0);
        signal NUMBER3          : std_logic_vector(3 downto 0);
 
        signal GPIO_0_buf_in    : std_logic_vector(35 downto 0);
        signal GPIO_1_buf_in    : std_logic_vector(35 downto 0);
 
        signal  vram_rdaddress_sig      : std_logic_vector(12 downto 0);
        signal  vram_wraddress_sig      : std_logic_vector(15 downto 0);
        signal  vram_data_sig           : std_logic_vector(7 downto 0);
        signal  vram_q_sig                      : std_logic_vector(7 downto 0);
        signal  vram_q_reg                      : std_logic_vector(7 downto 0);
        signal  vram_wren_sig           : std_logic;
        signal  vram_rden_sig           : std_logic;
        signal  vram_rdcycle_count      : std_logic_vector(3 downto 0);
        signal  vram_wrcycle_count      : std_logic_vector(3 downto 0);
        signal  VRAM_CLOCK                      : std_logic;
 
        -- PS/2 Keyboard
        signal ps2_read                         : std_logic;
        signal ps2_scan_ready           : std_logic;
        signal ps2_ascii_sig            : std_logic_vector(7 downto 0);
        signal ps2_ascii_reg1           : std_logic_vector(7 downto 0);
        signal ps2_ascii_reg            : std_logic_vector(7 downto 0);
 
begin
 
        HEX0 <= HEX_DISP0;
        HEX1 <= HEX_DISP1;
        HEX2 <= HEX_DISP2;
        HEX3 <= HEX_DISP3;
 
        SRAM_ADDR(15 downto 0) <= A - x"4000" when (A >= x"4000" and MReq_n = '0');
        -- SRAM_ADDR(15 downto 0) <= A - x"4000" when (A >= x"4000" and MReq_n = '0') else A;
        -- this is bad --> SRAM_ADDR(15 downto 0) <= A - x"4000";
        SRAM_DQ(15 downto 8) <= (others => 'Z');
        SRAM_ADDR(17 downto 16) <= "00";
        SRAM_UB_N <= '1';
        SRAM_LB_N <= '0';
        SRAM_CE_N <= '0';
        SRAM_WE_N <= Wr_n or MReq_n when A >= x"4000";
        SRAM_OE_N <= Rd_n;
 
        -- Write to SRAM (0x4000 - 0xFFFF)
        SRAM_DQ(7 downto 0) <= DO_CPU when (Wr_n = '0' and MReq_n = '0' and A >= x"4000") else (others => 'Z');
 
        -- Write into VRAM
        -- this is almost ok -->vram_wraddress_sig <= A - x"2000" when (A >= x"2000" and A < x"4000" and MReq_n = '0' and IORQ_n = '1');
        vram_wraddress_sig <= A - x"2000" when (A >= x"2000" and A < x"4000" and MReq_n = '0');
        -- vram_wraddress_sig <= A - x"2000";
        vram_wren_sig <= not Wr_n when (A >= x"2000" and A < x"4000" and IORQ_n = '1');
        vram_data_sig <= DO_CPU  when (Wr_n = '0' and MReq_n = '0' and A >= x"2000" and A < x"4000") else (others => 'Z');
        -- this is ok --> vram_data_sig <= DO_CPU;
 
        -- Input to Z80
        DI_CPU <= SRAM_DQ(7 downto 0) when (Rd_n = '0' and MReq_n = '0' and A >= x"4000") else
                        -- vram_q_sig when (A >= x"2000" and A < x"4000") else
                        D_ROM when (Rd_n = '0' and MReq_n = '0' and A < x"2000") else
                        SW(7 downto 0) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"20") else
                        ("0000" & KEY) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"30") else
                        GPIO_0(7 downto 0) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"A0") else
                        GPIO_0(15 downto 8) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"A1") else
                        GPIO_0(23 downto 16) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"A2") else
                        GPIO_0(31 downto 24) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"A3") else
                        ("0000" & GPIO_0(35 downto 32)) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"A4") else
                        GPIO_1(7 downto 0) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"B0") else
                        GPIO_1(15 downto 8) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"B1") else
                        GPIO_1(23 downto 16) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"B2") else
                        GPIO_1(31 downto 24) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"B3") else
                        ("0000" & GPIO_1(35 downto 32)) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"B4") else
                        ps2_ascii_reg when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"80");
 
        -- Process to latch leds and hex displays
        process(Clk_Z80)
        variable NUMBER0_sig    : std_logic_vector(3 downto 0);
        variable NUMBER1_sig    : std_logic_vector(3 downto 0);
        variable NUMBER2_sig    : std_logic_vector(3 downto 0);
        variable NUMBER3_sig    : std_logic_vector(3 downto 0);
        variable LEDG_sig               : std_logic_vector(7 downto 0);
        variable LEDR_sig               : std_logic_vector(9 downto 0);
 
        variable GPIO_0_buf_out: std_logic_vector(35 downto 0);
        variable GPIO_1_buf_out: std_logic_vector(35 downto 0);
 
        begin
 
                if Clk_Z80'event and Clk_Z80 = '1' then
                  if IORQ_n = '0' and Wr_n = '0' then
                        -- LEDG
                        if A(7 downto 0) = x"01" then
                                LEDG_sig := DO_CPU;
                        -- LEDR
                        elsif A(7 downto 0) = x"02" then
                                LEDR_sig(7 downto 0) := DO_CPU;
                        -- HEX1 and HEX0
                        elsif A(7 downto 0) = x"10" then
                                NUMBER0_sig := DO_CPU(3 downto 0);
                                NUMBER1_sig := DO_CPU(7 downto 4);
                        -- HEX3 and HEX2
                        elsif A(7 downto 0) = x"11" then
                                NUMBER2_sig := DO_CPU(3 downto 0);
                                NUMBER3_sig := DO_CPU(7 downto 4);
                        -- GPIO_0
                        elsif A(7 downto 0) = x"A0" then
                                GPIO_0_buf_out(7 downto 0)   := DO_CPU;
                        elsif A(7 downto 0) = x"A1" then
                                GPIO_0_buf_out(15 downto 8)  := DO_CPU;
                        elsif A(7 downto 0) = x"A2" then
                                GPIO_0_buf_out(23 downto 16) := DO_CPU;
                        elsif A(7 downto 0) = x"A3" then
                                GPIO_0_buf_out(31 downto 24) := DO_CPU;
                        elsif A(7 downto 0) = x"A4" then
                                GPIO_0_buf_out(35 downto 32) := DO_CPU(3 downto 0);
                        -- GPIO_1
                        elsif A(7 downto 0) = x"B0" then
                                GPIO_1_buf_out(7 downto 0)   := DO_CPU;
                        elsif A(7 downto 0) = x"B1" then
                                GPIO_1_buf_out(15 downto 8)  := DO_CPU;
                        elsif A(7 downto 0) = x"B2" then
                                GPIO_1_buf_out(23 downto 16) := DO_CPU;
                        elsif A(7 downto 0) = x"B3" then
                                GPIO_1_buf_out(31 downto 24) := DO_CPU;
                        elsif A(7 downto 0) = x"B4" then
                                GPIO_1_buf_out(35 downto 32) := DO_CPU(3 downto 0);
                        elsif A(7 downto 0) = x"C0" then
                                GPIO_0 <= GPIO_0_buf_out;
                        elsif A(7 downto 0) = x"C1" then
                                GPIO_1 <= GPIO_1_buf_out;
                        end if;
                  end if;
                end if;
 
                -- Latches the signals
                NUMBER0 <= NUMBER0_sig;
                NUMBER1 <= NUMBER1_sig;
                NUMBER2 <= NUMBER2_sig;
                NUMBER3 <= NUMBER3_sig;
                LEDR(7 downto 0) <= LEDR_sig(7 downto 0);
                LEDG <= LEDG_sig;
 
        end process;
 
 
        -- the following three processes deals with different clock domain signals
        ps2_process1: process(CLOCK_50)
        begin
                if CLOCK_50'event and CLOCK_50 = '1' then
                        if ps2_read = '1' then
                                if ps2_ascii_sig /= x"FF" then
                                        ps2_read <= '0';
                                        ps2_ascii_reg1 <= "00000000";
                                end if;
                        elsif ps2_scan_ready = '1' then
                                if ps2_ascii_sig = x"FF" then
                                        ps2_read <= '1';
                                else
                                        ps2_ascii_reg1 <= ps2_ascii_sig;
                                end if;
                        end if;
                end if;
        end process;
 
        ps2_process2: process(Clk_Z80)
        begin
                if Clk_Z80'event and Clk_Z80 = '1' then
                        ps2_ascii_reg <= ps2_ascii_reg1;
                end if;
        end process;
 
 
        One <= '1';
        Rst_n_s <= not SW(9);
 
        z80_inst: T80s
                port map (
                        M1_n => open,
                        MREQ_n => MReq_n,
                        IORQ_n => IORq_n,
                        RD_n => Rd_n,
                        WR_n => Wr_n,
                        RFSH_n => open,
                        HALT_n => open,
                        WAIT_n => One,
                        INT_n => One,
                        NMI_n => One,
                        RESET_n => Rst_n_s,
                        BUSRQ_n => One,
                        BUSAK_n => open,
                        CLK_n => Clk_Z80,
                        A => A,
                        DI => DI_CPU,
                        DO => DO_CPU
                );
 
        vga80x40_inst: work.video_80x40 port map (
                        CLOCK_50                => CLOCK_50,
                        VRAM_DATA               => vram_q_sig,
                        VRAM_ADDR               => vram_rdaddress_sig,
                        VRAM_CLOCK              => clk25mhz,
                        VRAM_WREN               => vram_rden_sig,
                        VGA_R                   => VGA_R,
                        VGA_G                   => VGA_G,
                        VGA_B                   => VGA_B,
                        VGA_HS                  => VGA_HS,
                        VGA_VS                  => VGA_VS
        );
 
        vram8k_inst : work.vram8k PORT MAP (
                rdaddress       => vram_rdaddress_sig,
                rdclock         => not clk25mhz,
                rden            => vram_rden_sig,
                q                       => vram_q_sig,
                wraddress       => vram_wraddress_sig(12 downto 0),
                wrclock         => Clk_Z80,
                wren            => vram_wren_sig,
                data            => vram_data_sig
        );
 
        rom_inst: rom
                port map (
                        Clk => Clk_Z80,
                        A       => A,
                        D       => D_ROM
                );
 
        clkdiv_inst: clk_div
        port map (
                clock_25Mhz                             => clk25mhz,
                clock_1MHz                              => open,
                clock_100KHz                    => open,
                clock_10KHz                             => open,
                clock_1KHz                              => open,
                clock_100Hz                             => clk100hz,
                clock_10Hz                              => clk10hz,
                clock_1Hz                               => clk1hz
        );
 
        clock_z80_inst : Clock_357Mhz
                port map (
                        clock_50Mhz             => CLOCK_50,
                        clock_357Mhz    => Clk_Z80
        );
 
        DISPHEX0 : decoder_7seg PORT MAP (
                NUMBER                  =>      NUMBER0,
                HEX_DISP                =>      HEX_DISP0
        );
 
        DISPHEX1 : decoder_7seg PORT MAP (
                NUMBER                  =>      NUMBER1,
                HEX_DISP                =>      HEX_DISP1
        );
 
        DISPHEX2 : decoder_7seg PORT MAP (
                NUMBER                  =>      NUMBER2,
                HEX_DISP                =>      HEX_DISP2
        );
 
        DISPHEX3 : decoder_7seg PORT MAP (
                NUMBER                  =>      NUMBER3,
                HEX_DISP                =>      HEX_DISP3
        );
 
        ps2_kbd_inst : work.ps2kbd PORT MAP (
                keyboard_clk    => PS2_CLK,
                keyboard_data   => PS2_DAT,
                clock                   => CLOCK_50,
                clkdelay                => clk100hz,
                reset                   => Rst_n_s,
                read                    => ps2_read,
                scan_ready              => ps2_scan_ready,
                ps2_ascii_code  => ps2_ascii_sig
        );
 
        UART_TXD <= 'Z';
        DRAM_ADDR <= (others => '0');
        DRAM_LDQM <= '0';
        DRAM_UDQM <= '0';
        DRAM_WE_N <= '1';
        DRAM_CAS_N <= '1';
        DRAM_RAS_N <= '1';
        DRAM_CS_N <= '1';
        DRAM_BA_0 <= '0';
        DRAM_BA_1 <= '0';
        DRAM_CLK <= '0';
        DRAM_CKE <= '0';
        FL_ADDR <= (others => '0');
        FL_WE_N <= '1';
        FL_RST_N <= '0';
        FL_OE_N <= '1';
        FL_CE_N <= '1';
        TDO <= '0';
        I2C_SCLK <= '0';
        AUD_DACDAT <= '0';
        AUD_XCK <= '0';
        -- Set all bidirectional ports to tri-state
        DRAM_DQ     <= (others => 'Z');
        FL_DQ       <= (others => 'Z');
        I2C_SDAT    <= 'Z';
        AUD_ADCLRCK <= 'Z';
        AUD_DACLRCK <= 'Z';
        AUD_BCLK    <= 'Z';
        GPIO_0 <= (others => 'Z');
        GPIO_1 <= (others => 'Z');
end;

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[/] [z80soc/] [branches/] [RonivonCosta/] [DE1/] [rtl/] [VHDL/] [top_de1.vhd] - Blame information for rev 41

Line No.	Rev	Author	Line
1	11	rrred	`-------------------------------------------------------------------------------------------------`
2			`-- Z80_Soc (Z80 System on Chip)`
3			`--`
4			`-- Version 0.5 Beta`
5			`--`
6			`-- Developer: Ronivon Candido Costa`
7			`-- Release Date: 2008 / 04 / 16`
8			`--`
9			`-- Based on the T80 core: http://www.opencores.org/projects.cgi/web/t80`
10			`-- This version developed and tested on: Altera DE1 Development Board`
11			`--`
12			`-- Peripherals configured (Using Ports):`
13			`--`
14			`-- 08 KB Internal ROM Read (0x0000h - 0x1FFFh)`
15			`-- 08 KB INTERNAL VRAM Write (0x2000h - 0x3FFFh)`
16			`-- 48 KB External SRAM Read/Write (0x4000h - 0xFFFFh)`
17			`-- 08 Green Leds Out (Port 0x01h)`
18			`-- 08 Red Leds Out (Port 0x02h)`
19			`-- 04 Seven Seg displays Out (Ports 0x10h and 0x11h)`
20			`-- 36 Pins GPIO0 In/Out (Ports 0xA0h, 0xA1h, 0xA2h, 0xA3h, 0xA4h, 0xC0h)`
21			`-- 36 Pins GPIO1 In/Out (Ports 0xB0h, 0xB1h, 0xB2h, 0xB3h, 0xB4h, 0xC1h)`
22			`-- 08 Switches In (Port 0x20h)`
23			`-- 04 Push buttons In (Port 0x30h)`
24			`-- PS/2 keyboard In (Port 0x80h)`
25			`-- Video Out 40x30 (VGA) Out (0x2000h - 0x24B0)`
26			`--`
27			`-- TO-DO:`
28			`-- - Monitor program to introduce Z80 Assmebly codes and run`
29			`-- - Serial communication, to download assembly code from PC`
30			`-- - Add hardware support for 80x40 Video out`
31			`-- - SD/MMC card interface to read/store data and programs`
32			`-------------------------------------------------------------------------------------------------`
33
34			`library IEEE;`
35			`use IEEE.std_logic_1164.all;`
36			`use IEEE.std_logic_arith.all;`
37			`use IEEE.std_logic_unsigned.all;`
38
39			`entity TOP_DE1 is`
40			`port(`
41
42			`-- Clocks`
43			`CLOCK_27, -- 27 MHz`
44			`CLOCK_50, -- 50 MHz`
45			`EXT_CLOCK : in std_logic; -- External Clock`
46
47			`-- Buttons and switches`
48			`KEY : in std_logic_vector(3 downto 0); -- Push buttons`
49			`SW : in std_logic_vector(9 downto 0); -- Switches`
50
51			`-- LED displays`
52			`HEX0, HEX1, HEX2, HEX3 -- 7-segment displays`
53			`: out std_logic_vector(6 downto 0);`
54			`LEDG : out std_logic_vector(7 downto 0); -- Green LEDs`
55			`LEDR : out std_logic_vector(9 downto 0); -- Red LEDs`
56
57			`-- RS-232 interface`
58			`UART_TXD : out std_logic; -- UART transmitter`
59			`UART_RXD : in std_logic; -- UART receiver`
60
61			`-- IRDA interface`
62
63			`-- IRDA_TXD : out std_logic; -- IRDA Transmitter`
64			`IRDA_RXD : in std_logic; -- IRDA Receiver`
65
66			`-- SDRAM`
67			`DRAM_DQ : inout std_logic_vector(15 downto 0); -- Data Bus`
68			`DRAM_ADDR : out std_logic_vector(11 downto 0); -- Address Bus`
69			`DRAM_LDQM, -- Low-byte Data Mask`
70			`DRAM_UDQM, -- High-byte Data Mask`
71			`DRAM_WE_N, -- Write Enable`
72			`DRAM_CAS_N, -- Column Address Strobe`
73			`DRAM_RAS_N, -- Row Address Strobe`
74			`DRAM_CS_N, -- Chip Select`
75			`DRAM_BA_0, -- Bank Address 0`
76			`DRAM_BA_1, -- Bank Address 0`
77			`DRAM_CLK, -- Clock`
78			`DRAM_CKE : out std_logic; -- Clock Enable`
79
80			`-- FLASH`
81			`FL_DQ : inout std_logic_vector(7 downto 0); -- Data bus`
82			`FL_ADDR : out std_logic_vector(21 downto 0); -- Address bus`
83			`FL_WE_N, -- Write Enable`
84			`FL_RST_N, -- Reset`
85			`FL_OE_N, -- Output Enable`
86			`FL_CE_N : out std_logic; -- Chip Enable`
87
88			`-- SRAM`
89			`SRAM_DQ : inout std_logic_vector(15 downto 0); -- Data bus 16 Bits`
90			`SRAM_ADDR : out std_logic_vector(17 downto 0); -- Address bus 18 Bits`
91			`SRAM_UB_N, -- High-byte Data Mask`
92			`SRAM_LB_N, -- Low-byte Data Mask`
93			`SRAM_WE_N, -- Write Enable`
94			`SRAM_CE_N, -- Chip Enable`
95			`SRAM_OE_N : out std_logic; -- Output Enable`
96
97			`-- SD card interface`
98			`SD_DAT : in std_logic; -- SD Card Data SD pin 7 "DAT 0/DataOut"`
99			`SD_DAT3 : out std_logic; -- SD Card Data 3 SD pin 1 "DAT 3/nCS"`
100			`SD_CMD : out std_logic; -- SD Card Command SD pin 2 "CMD/DataIn"`
101			`SD_CLK : out std_logic; -- SD Card Clock SD pin 5 "CLK"`
102
103			`-- USB JTAG link`
104			`TDI, -- CPLD -> FPGA (data in)`
105			`TCK, -- CPLD -> FPGA (clk)`
106			`TCS : in std_logic; -- CPLD -> FPGA (CS)`
107			`TDO : out std_logic; -- FPGA -> CPLD (data out)`
108
109			`-- I2C bus`
110			`I2C_SDAT : inout std_logic; -- I2C Data`
111			`I2C_SCLK : out std_logic; -- I2C Clock`
112
113			`-- PS/2 port`
114			`PS2_DAT, -- Data`
115			`PS2_CLK : inout std_logic; -- Clock`
116
117			`-- VGA output`
118			`VGA_HS, -- H_SYNC`
119			`VGA_VS : out std_logic; -- SYNC`
120			`VGA_R, -- Red[3:0]`
121			`VGA_G, -- Green[3:0]`
122			`VGA_B : out std_logic_vector(3 downto 0); -- Blue[3:0]`
123
124			`-- Audio CODEC`
125			`AUD_ADCLRCK : inout std_logic; -- ADC LR Clock`
126			`AUD_ADCDAT : in std_logic; -- ADC Data`
127			`AUD_DACLRCK : inout std_logic; -- DAC LR Clock`
128			`AUD_DACDAT : out std_logic; -- DAC Data`
129			`AUD_BCLK : inout std_logic; -- Bit-Stream Clock`
130			`AUD_XCK : out std_logic; -- Chip Clock`
131
132			`-- General-purpose I/O`
133			`GPIO_0, -- GPIO Connection 0`
134			`GPIO_1 : inout std_logic_vector(35 downto 0) -- GPIO Connection 1`
135			`);`
136			`end TOP_DE1;`
137
138			`architecture rtl of TOP_DE1 is`
139
140			`component T80s`
141			`generic(`
142			`Mode : integer := 0);`
143			`port (`
144			`RESET_n : in std_logic;`
145			`CLK_n : in std_logic;`
146			`WAIT_n : in std_logic;`
147			`INT_n : in std_logic;`
148			`NMI_n : in std_logic;`
149			`BUSRQ_n : in std_logic;`
150			`M1_n : out std_logic;`
151			`MREQ_n : out std_logic;`
152			`IORQ_n : out std_logic;`
153			`RD_n : out std_logic;`
154			`WR_n : out std_logic;`
155			`RFSH_n : out std_logic;`
156			`HALT_n : out std_logic;`
157			`BUSAK_n : out std_logic;`
158			`A : out std_logic_vector(15 downto 0);`
159			`DI : in std_logic_vector(7 downto 0);`
160			`DO : out std_logic_vector(7 downto 0));`
161			`end component;`
162
163			`component rom`
164			`port (`
165			`Clk : in std_logic;`
166			`A : in std_logic_vector(15 downto 0);`
167			`D : out std_logic_vector(7 downto 0));`
168			`end component;`
169
170			`component Clock_357Mhz`
171			`PORT (`
172			`clock_50Mhz : IN STD_LOGIC;`
173			`clock_357Mhz : OUT STD_LOGIC);`
174			`end component;`
175
176			`component clk_div`
177			`PORT`
178			`(`
179			`clock_25Mhz : IN STD_LOGIC;`
180			`clock_1MHz : OUT STD_LOGIC;`
181			`clock_100KHz : OUT STD_LOGIC;`
182			`clock_10KHz : OUT STD_LOGIC;`
183			`clock_1KHz : OUT STD_LOGIC;`
184			`clock_100Hz : OUT STD_LOGIC;`
185			`clock_10Hz : OUT STD_LOGIC;`
186			`clock_1Hz : OUT STD_LOGIC);`
187			`end component;`
188
189			`component decoder_7seg`
190			`port (`
191			`NUMBER : in std_logic_vector(3 downto 0);`
192			`HEX_DISP : out std_logic_vector(6 downto 0));`
193			`end component;`
194
195			`signal MREQ_n : std_logic;`
196			`signal IORQ_n : std_logic;`
197			`signal RD_n : std_logic;`
198			`signal WR_n : std_logic;`
199			`signal MWr_n : std_logic;`
200			`signal Rst_n_s : std_logic;`
201			`signal Clk_Z80 : std_logic;`
202			`signal DI_CPU : std_logic_vector(7 downto 0);`
203			`signal DO_CPU : std_logic_vector(7 downto 0);`
204			`signal A : std_logic_vector(15 downto 0);`
205			`signal One : std_logic;`
206
207			`signal D_ROM : std_logic_vector(7 downto 0);`
208
209			`signal clk25mhz_sig : std_logic;`
210			`signal clk25mhz : std_logic;`
211			`signal clk1hz : std_logic;`
212			`signal clk10hz : std_logic;`
213			`signal clk100hz : std_logic;`
214
215			`signal HEX_DISP0 : std_logic_vector(6 downto 0);`
216			`signal HEX_DISP1 : std_logic_vector(6 downto 0);`
217			`signal HEX_DISP2 : std_logic_vector(6 downto 0);`
218			`signal HEX_DISP3 : std_logic_vector(6 downto 0);`
219
220			`signal NUMBER0 : std_logic_vector(3 downto 0);`
221			`signal NUMBER1 : std_logic_vector(3 downto 0);`
222			`signal NUMBER2 : std_logic_vector(3 downto 0);`
223			`signal NUMBER3 : std_logic_vector(3 downto 0);`
224
225			`signal GPIO_0_buf_in : std_logic_vector(35 downto 0);`
226			`signal GPIO_1_buf_in : std_logic_vector(35 downto 0);`
227
228			`signal vram_rdaddress_sig : std_logic_vector(12 downto 0);`
229			`signal vram_wraddress_sig : std_logic_vector(15 downto 0);`
230			`signal vram_data_sig : std_logic_vector(7 downto 0);`
231			`signal vram_q_sig : std_logic_vector(7 downto 0);`
232			`signal vram_q_reg : std_logic_vector(7 downto 0);`
233			`signal vram_wren_sig : std_logic;`
234			`signal vram_rden_sig : std_logic;`
235			`signal vram_rdcycle_count : std_logic_vector(3 downto 0);`
236			`signal vram_wrcycle_count : std_logic_vector(3 downto 0);`
237			`signal VRAM_CLOCK : std_logic;`
238
239			`-- PS/2 Keyboard`
240			`signal ps2_read : std_logic;`
241			`signal ps2_scan_ready : std_logic;`
242			`signal ps2_ascii_sig : std_logic_vector(7 downto 0);`
243			`signal ps2_ascii_reg1 : std_logic_vector(7 downto 0);`
244			`signal ps2_ascii_reg : std_logic_vector(7 downto 0);`
245
246			`begin`
247
248			`HEX0 <= HEX_DISP0;`
249			`HEX1 <= HEX_DISP1;`
250			`HEX2 <= HEX_DISP2;`
251			`HEX3 <= HEX_DISP3;`
252
253			`SRAM_ADDR(15 downto 0) <= A - x"4000" when (A >= x"4000" and MReq_n = '0');`
254			`-- SRAM_ADDR(15 downto 0) <= A - x"4000" when (A >= x"4000" and MReq_n = '0') else A;`
255			`-- this is bad --> SRAM_ADDR(15 downto 0) <= A - x"4000";`
256			`SRAM_DQ(15 downto 8) <= (others => 'Z');`
257			`SRAM_ADDR(17 downto 16) <= "00";`
258			`SRAM_UB_N <= '1';`
259			`SRAM_LB_N <= '0';`
260			`SRAM_CE_N <= '0';`
261			`SRAM_WE_N <= Wr_n or MReq_n when A >= x"4000";`
262			`SRAM_OE_N <= Rd_n;`
263
264			`-- Write to SRAM (0x4000 - 0xFFFF)`
265			`SRAM_DQ(7 downto 0) <= DO_CPU when (Wr_n = '0' and MReq_n = '0' and A >= x"4000") else (others => 'Z');`
266
267			`-- Write into VRAM`
268			`-- this is almost ok -->vram_wraddress_sig <= A - x"2000" when (A >= x"2000" and A < x"4000" and MReq_n = '0' and IORQ_n = '1');`
269			`vram_wraddress_sig <= A - x"2000" when (A >= x"2000" and A < x"4000" and MReq_n = '0');`
270			`-- vram_wraddress_sig <= A - x"2000";`
271			`vram_wren_sig <= not Wr_n when (A >= x"2000" and A < x"4000" and IORQ_n = '1');`
272			`vram_data_sig <= DO_CPU when (Wr_n = '0' and MReq_n = '0' and A >= x"2000" and A < x"4000") else (others => 'Z');`
273			`-- this is ok --> vram_data_sig <= DO_CPU;`
274
275			`-- Input to Z80`
276			`DI_CPU <= SRAM_DQ(7 downto 0) when (Rd_n = '0' and MReq_n = '0' and A >= x"4000") else`
277			`-- vram_q_sig when (A >= x"2000" and A < x"4000") else`
278			`D_ROM when (Rd_n = '0' and MReq_n = '0' and A < x"2000") else`
279			`SW(7 downto 0) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"20") else`
280			`("0000" & KEY) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"30") else`
281			`GPIO_0(7 downto 0) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"A0") else`
282			`GPIO_0(15 downto 8) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"A1") else`
283			`GPIO_0(23 downto 16) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"A2") else`
284			`GPIO_0(31 downto 24) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"A3") else`
285			`("0000" & GPIO_0(35 downto 32)) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"A4") else`
286			`GPIO_1(7 downto 0) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"B0") else`
287			`GPIO_1(15 downto 8) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"B1") else`
288			`GPIO_1(23 downto 16) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"B2") else`
289			`GPIO_1(31 downto 24) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"B3") else`
290			`("0000" & GPIO_1(35 downto 32)) when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"B4") else`
291			`ps2_ascii_reg when (IORQ_n = '0' and Rd_n = '0' and A(7 downto 0) = x"80");`
292
293			`-- Process to latch leds and hex displays`
294			`process(Clk_Z80)`
295			`variable NUMBER0_sig : std_logic_vector(3 downto 0);`
296			`variable NUMBER1_sig : std_logic_vector(3 downto 0);`
297			`variable NUMBER2_sig : std_logic_vector(3 downto 0);`
298			`variable NUMBER3_sig : std_logic_vector(3 downto 0);`
299			`variable LEDG_sig : std_logic_vector(7 downto 0);`
300			`variable LEDR_sig : std_logic_vector(9 downto 0);`
301
302			`variable GPIO_0_buf_out: std_logic_vector(35 downto 0);`
303			`variable GPIO_1_buf_out: std_logic_vector(35 downto 0);`
304
305			`begin`
306
307			`if Clk_Z80'event and Clk_Z80 = '1' then`
308			`if IORQ_n = '0' and Wr_n = '0' then`
309			`-- LEDG`
310			`if A(7 downto 0) = x"01" then`
311			`LEDG_sig := DO_CPU;`
312			`-- LEDR`
313			`elsif A(7 downto 0) = x"02" then`
314			`LEDR_sig(7 downto 0) := DO_CPU;`
315			`-- HEX1 and HEX0`
316			`elsif A(7 downto 0) = x"10" then`
317			`NUMBER0_sig := DO_CPU(3 downto 0);`
318			`NUMBER1_sig := DO_CPU(7 downto 4);`
319			`-- HEX3 and HEX2`
320			`elsif A(7 downto 0) = x"11" then`
321			`NUMBER2_sig := DO_CPU(3 downto 0);`
322			`NUMBER3_sig := DO_CPU(7 downto 4);`
323			`-- GPIO_0`
324			`elsif A(7 downto 0) = x"A0" then`
325			`GPIO_0_buf_out(7 downto 0) := DO_CPU;`
326			`elsif A(7 downto 0) = x"A1" then`
327			`GPIO_0_buf_out(15 downto 8) := DO_CPU;`
328			`elsif A(7 downto 0) = x"A2" then`
329			`GPIO_0_buf_out(23 downto 16) := DO_CPU;`
330			`elsif A(7 downto 0) = x"A3" then`
331			`GPIO_0_buf_out(31 downto 24) := DO_CPU;`
332			`elsif A(7 downto 0) = x"A4" then`
333			`GPIO_0_buf_out(35 downto 32) := DO_CPU(3 downto 0);`
334			`-- GPIO_1`
335			`elsif A(7 downto 0) = x"B0" then`
336			`GPIO_1_buf_out(7 downto 0) := DO_CPU;`
337			`elsif A(7 downto 0) = x"B1" then`
338			`GPIO_1_buf_out(15 downto 8) := DO_CPU;`
339			`elsif A(7 downto 0) = x"B2" then`
340			`GPIO_1_buf_out(23 downto 16) := DO_CPU;`
341			`elsif A(7 downto 0) = x"B3" then`
342			`GPIO_1_buf_out(31 downto 24) := DO_CPU;`
343			`elsif A(7 downto 0) = x"B4" then`
344			`GPIO_1_buf_out(35 downto 32) := DO_CPU(3 downto 0);`
345			`elsif A(7 downto 0) = x"C0" then`
346			`GPIO_0 <= GPIO_0_buf_out;`
347			`elsif A(7 downto 0) = x"C1" then`
348			`GPIO_1 <= GPIO_1_buf_out;`
349			`end if;`
350			`end if;`
351			`end if;`
352
353			`-- Latches the signals`
354			`NUMBER0 <= NUMBER0_sig;`
355			`NUMBER1 <= NUMBER1_sig;`
356			`NUMBER2 <= NUMBER2_sig;`
357			`NUMBER3 <= NUMBER3_sig;`
358			`LEDR(7 downto 0) <= LEDR_sig(7 downto 0);`
359			`LEDG <= LEDG_sig;`
360
361			`end process;`
362
363
364			`-- the following three processes deals with different clock domain signals`
365			`ps2_process1: process(CLOCK_50)`
366			`begin`
367			`if CLOCK_50'event and CLOCK_50 = '1' then`
368			`if ps2_read = '1' then`
369			`if ps2_ascii_sig /= x"FF" then`
370			`ps2_read <= '0';`
371			`ps2_ascii_reg1 <= "00000000";`
372			`end if;`
373			`elsif ps2_scan_ready = '1' then`
374			`if ps2_ascii_sig = x"FF" then`
375			`ps2_read <= '1';`
376			`else`
377			`ps2_ascii_reg1 <= ps2_ascii_sig;`
378			`end if;`
379			`end if;`
380			`end if;`
381			`end process;`
382
383			`ps2_process2: process(Clk_Z80)`
384			`begin`
385			`if Clk_Z80'event and Clk_Z80 = '1' then`
386			`ps2_ascii_reg <= ps2_ascii_reg1;`
387			`end if;`
388			`end process;`
389
390
391			`One <= '1';`
392			`Rst_n_s <= not SW(9);`
393
394			`z80_inst: T80s`
395			`port map (`
396			`M1_n => open,`
397			`MREQ_n => MReq_n,`
398			`IORQ_n => IORq_n,`
399			`RD_n => Rd_n,`
400			`WR_n => Wr_n,`
401			`RFSH_n => open,`
402			`HALT_n => open,`
403			`WAIT_n => One,`
404			`INT_n => One,`
405			`NMI_n => One,`
406			`RESET_n => Rst_n_s,`
407			`BUSRQ_n => One,`
408			`BUSAK_n => open,`
409			`CLK_n => Clk_Z80,`
410			`A => A,`
411			`DI => DI_CPU,`
412			`DO => DO_CPU`
413			`);`
414
415			`vga80x40_inst: work.video_80x40 port map (`
416			`CLOCK_50 => CLOCK_50,`
417			`VRAM_DATA => vram_q_sig,`
418			`VRAM_ADDR => vram_rdaddress_sig,`
419			`VRAM_CLOCK => clk25mhz,`
420			`VRAM_WREN => vram_rden_sig,`
421			`VGA_R => VGA_R,`
422			`VGA_G => VGA_G,`
423			`VGA_B => VGA_B,`
424			`VGA_HS => VGA_HS,`
425			`VGA_VS => VGA_VS`
426			`);`
427
428			`vram8k_inst : work.vram8k PORT MAP (`
429			`rdaddress => vram_rdaddress_sig,`
430			`rdclock => not clk25mhz,`
431			`rden => vram_rden_sig,`
432			`q => vram_q_sig,`
433			`wraddress => vram_wraddress_sig(12 downto 0),`
434			`wrclock => Clk_Z80,`
435			`wren => vram_wren_sig,`
436			`data => vram_data_sig`
437			`);`
438
439			`rom_inst: rom`
440			`port map (`
441			`Clk => Clk_Z80,`
442			`A => A,`
443			`D => D_ROM`
444			`);`
445
446			`clkdiv_inst: clk_div`
447			`port map (`
448			`clock_25Mhz => clk25mhz,`
449			`clock_1MHz => open,`
450			`clock_100KHz => open,`
451			`clock_10KHz => open,`
452			`clock_1KHz => open,`
453			`clock_100Hz => clk100hz,`
454			`clock_10Hz => clk10hz,`
455			`clock_1Hz => clk1hz`
456			`);`
457
458			`clock_z80_inst : Clock_357Mhz`
459			`port map (`
460			`clock_50Mhz => CLOCK_50,`
461			`clock_357Mhz => Clk_Z80`
462			`);`
463
464			`DISPHEX0 : decoder_7seg PORT MAP (`
465			`NUMBER => NUMBER0,`
466			`HEX_DISP => HEX_DISP0`
467			`);`
468
469			`DISPHEX1 : decoder_7seg PORT MAP (`
470			`NUMBER => NUMBER1,`
471			`HEX_DISP => HEX_DISP1`
472			`);`
473
474			`DISPHEX2 : decoder_7seg PORT MAP (`
475			`NUMBER => NUMBER2,`
476			`HEX_DISP => HEX_DISP2`
477			`);`
478
479			`DISPHEX3 : decoder_7seg PORT MAP (`
480			`NUMBER => NUMBER3,`
481			`HEX_DISP => HEX_DISP3`
482			`);`
483
484			`ps2_kbd_inst : work.ps2kbd PORT MAP (`
485			`keyboard_clk => PS2_CLK,`
486			`keyboard_data => PS2_DAT,`
487			`clock => CLOCK_50,`
488			`clkdelay => clk100hz,`
489			`reset => Rst_n_s,`
490			`read => ps2_read,`
491			`scan_ready => ps2_scan_ready,`
492			`ps2_ascii_code => ps2_ascii_sig`
493			`);`
494
495			`UART_TXD <= 'Z';`
496			`DRAM_ADDR <= (others => '0');`
497			`DRAM_LDQM <= '0';`
498			`DRAM_UDQM <= '0';`
499			`DRAM_WE_N <= '1';`
500			`DRAM_CAS_N <= '1';`
501			`DRAM_RAS_N <= '1';`
502			`DRAM_CS_N <= '1';`
503			`DRAM_BA_0 <= '0';`
504			`DRAM_BA_1 <= '0';`
505			`DRAM_CLK <= '0';`
506			`DRAM_CKE <= '0';`
507			`FL_ADDR <= (others => '0');`
508			`FL_WE_N <= '1';`
509			`FL_RST_N <= '0';`
510			`FL_OE_N <= '1';`
511			`FL_CE_N <= '1';`
512			`TDO <= '0';`
513			`I2C_SCLK <= '0';`
514			`AUD_DACDAT <= '0';`
515			`AUD_XCK <= '0';`
516			`-- Set all bidirectional ports to tri-state`
517			`DRAM_DQ <= (others => 'Z');`
518			`FL_DQ <= (others => 'Z');`
519			`I2C_SDAT <= 'Z';`
520			`AUD_ADCLRCK <= 'Z';`
521			`AUD_DACLRCK <= 'Z';`
522			`AUD_BCLK <= 'Z';`
523			`GPIO_0 <= (others => 'Z');`
524			`GPIO_1 <= (others => 'Z');`
525			`end;`