Subversion Repositories neo430

-- #################################################################################################

-- #  << NEO430 - Processor Top Entity >>                                                          #

-- # ********************************************************************************************* #

-- # This is the top entity of the NEO430 processor. Instantiate this unit in your own project and #

-- # define all the configuration generics according to your needs. Alternatively, you can use one #

-- # of the other top entities provided in rtl\top_templates                                       #

-- # Check the processor's documentary for more information: doc\NEO430.pdf                        #

-- # ********************************************************************************************* #

-- #  The NEO430 processor:                                                                        #

-- #  - Reset and clock generators                                                                 #

-- #  - External IRQ synchronizer                                                                  #

-- #  - NEO430 CPU (MSP430(TM)-ISA-compatible) (CPU)                                               #

-- #  - Internal RAM or ROM (configurable size) for code (IMEM)                                    #

-- #  - Internal RAM (configurable size) for data (and code) (DMEM)                                #

-- #  - Sysconfig (infomem for various system information) (SYSCONFIG)                             #

-- #  - Optional 16-bit multiplier/divider unit (MULDIV)                                           #

-- #  - Optional 16-bit IN and 16-bit OUT GPIO port with pin-change interrupt (GPIO)               #

-- #  - Optional 32-bit Wishbone interface (WB32)                                                  #

-- #  - Optional High precision timer (TIMER)                                                      #

-- #  - Optional Universal Asynchronous Receiver and Transmitter (UART)                            #

-- #  - Optional Serial Peripheral Interface (SPI)                                                 #

-- #  - Optional Internal ROM for bootloader (BOOTLD)                                              #

-- #  - Optional Watchdog Timer (WDT)                                                              #

-- #  - Optional CRC16/32 Module (CRC16/32)                                                        #

-- #  - Optional Custom Functions Unit to implement user-defined processor extension (CFU)         #

-- #  - Optional Pulse Width Modulation controller (PWM)                                           #

-- #  - Optional Two Wire Serial Interface (TWI)                                                   #

-- #  - Optional True Random Number Generator (TRNG)                                               #

-- #  - Optional External Interrupts Controller (EXIRQ)                                            #

-- #  - Optional Arbitrary Frequency Generator (FREQ_GEN)                                          #

-- # ********************************************************************************************* #

-- # BSD 3-Clause License                                                                          #

-- #                                                                                               #

-- # Copyright (c) 2020, Stephan Nolting. All rights reserved.                                     #

-- #                                                                                               #

-- # Redistribution and use in source and binary forms, with or without modification, are          #

-- # permitted provided that the following conditions are met:                                     #

-- #                                                                                               #

-- # 1. Redistributions of source code must retain the above copyright notice, this list of        #

-- #    conditions and the following disclaimer.                                                   #

-- #                                                                                               #

-- # 2. 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.                                                            #

-- #                                                                                               #

-- # 3. Neither the name of the copyright holder nor the names of its contributors may be used to  #

-- #    endorse or promote products derived from this software without specific prior written      #

-- #    permission.                                                                                #

-- #                                                                                               #

-- # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE    #

-- # COPYRIGHT HOLDER OR CONTRIBUTORS 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.                                                            #

-- # ********************************************************************************************* #

-- # The NEO430 Processor - https://github.com/stnolting/neo430                                    #

-- #################################################################################################

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

library neo430;

use neo430.neo430_package.all;

entity neo430_top is

  generic (

    -- general configuration --

    CLOCK_SPEED  : natural := 100000000; -- main clock in Hz

    IMEM_SIZE    : natural := 4*1024; -- internal IMEM size in bytes, max 48kB (default=4kB)

    DMEM_SIZE    : natural := 2*1024; -- internal DMEM size in bytes, max 12kB (default=2kB)

    -- additional configuration --

    USER_CODE    : std_ulogic_vector(15 downto 0) := x"0000"; -- custom user code

    -- module configuration --

    MULDIV_USE   : boolean := true;  -- implement multiplier/divider unit? (default=true)

    WB32_USE     : boolean := true;  -- implement WB32 unit? (default=true)

    WDT_USE      : boolean := true;  -- implement WDT? (default=true)

    GPIO_USE     : boolean := true;  -- implement GPIO unit? (default=true)

    TIMER_USE    : boolean := true;  -- implement timer? (default=true)

    UART_USE     : boolean := true;  -- implement UART? (default=true)

    CRC_USE      : boolean := true;  -- implement CRC unit? (default=true)

    CFU_USE      : boolean := false; -- implement custom functions unit? (default=false)

    PWM_USE      : boolean := true;  -- implement PWM controller? (default=true)

    TWI_USE      : boolean := true;  -- implement two wire serial interface? (default=true)

    SPI_USE      : boolean := true;  -- implement SPI? (default=true)

    TRNG_USE     : boolean := false; -- implement TRNG? (default=false)

    EXIRQ_USE    : boolean := true;  -- implement EXIRQ? (default=true)

    FREQ_GEN_USE : boolean := true;  -- implement FREQ_GEN? (default=true)

    -- boot configuration --

    BOOTLD_USE   : boolean := true;  -- implement and use bootloader? (default=true)

    IMEM_AS_ROM  : boolean := false  -- implement IMEM as read-only memory? (default=false)

  );

  port (

    -- global control --

    clk_i      : in  std_ulogic; -- global clock, rising edge

    rst_i      : in  std_ulogic; -- global reset, async, LOW-active

    -- parallel io --

    gpio_o     : out std_ulogic_vector(15 downto 0); -- parallel output

    gpio_i     : in  std_ulogic_vector(15 downto 0); -- parallel input

    -- pwm channels --

    pwm_o      : out std_ulogic_vector(03 downto 0); -- pwm channels

    -- arbitrary frequency generator --

    freq_gen_o : out std_ulogic_vector(02 downto 0); -- programmable frequency output

    -- serial com --

    uart_txd_o : out std_ulogic; -- UART send data

    uart_rxd_i : in  std_ulogic; -- UART receive data

    spi_sclk_o : out std_ulogic; -- serial clock line

    spi_mosi_o : out std_ulogic; -- serial data line out

    spi_miso_i : in  std_ulogic; -- serial data line in

    spi_cs_o   : out std_ulogic_vector(05 downto 0); -- SPI CS

    twi_sda_io : inout std_logic; -- twi serial data line

    twi_scl_io : inout std_logic; -- twi serial clock line

    -- 32-bit wishbone interface --

    wb_adr_o   : out std_ulogic_vector(31 downto 0); -- address

    wb_dat_i   : in  std_ulogic_vector(31 downto 0); -- read data

    wb_dat_o   : out std_ulogic_vector(31 downto 0); -- write data

    wb_we_o    : out std_ulogic; -- read/write

    wb_sel_o   : out std_ulogic_vector(03 downto 0); -- byte enable

    wb_stb_o   : out std_ulogic; -- strobe

    wb_cyc_o   : out std_ulogic; -- valid cycle

    wb_ack_i   : in  std_ulogic; -- transfer acknowledge

    -- external interrupts --

    ext_irq_i  : in  std_ulogic_vector(07 downto 0); -- external interrupt request lines (active HI)

    ext_ack_o  : out std_ulogic_vector(07 downto 0)  -- external interrupt request acknowledges

  );

end neo430_top;

architecture neo430_top_rtl of neo430_top is

  -- generators --

  signal rst_i_sync0    : std_ulogic;

  signal rst_i_sync1    : std_ulogic;

  signal rst_gen        : std_ulogic_vector(03 downto 0) := (others => '0'); -- reset on bitstream upload

  signal ext_rst        : std_ulogic;

  signal sys_rst        : std_ulogic;

  signal wdt_rst        : std_ulogic;

  signal clk_div        : std_ulogic_vector(11 downto 0);

  signal clk_div_ff     : std_ulogic_vector(11 downto 0);

  signal clk_gen        : std_ulogic_vector(07 downto 0);

  signal timer_cg_en    : std_ulogic;

  signal uart_cg_en     : std_ulogic;

  signal spi_cg_en      : std_ulogic;

  signal wdt_cg_en      : std_ulogic;

  signal pwm_cg_en      : std_ulogic;

  signal twi_cg_en      : std_ulogic;

  signal cfu_cg_en      : std_ulogic;

  signal freq_gen_cg_en : std_ulogic;

  type cpu_bus_t is record

    rd_en : std_ulogic;

    wr_en : std_ulogic_vector(01 downto 0);

    addr  : std_ulogic_vector(15 downto 0);

    rdata : std_ulogic_vector(15 downto 0);

    wdata : std_ulogic_vector(15 downto 0);

  end record;

  -- main CPU communication bus --

  signal cpu_bus  : cpu_bus_t;

  signal io_acc   : std_ulogic;

  signal io_wr_en : std_ulogic;

  signal io_rd_en : std_ulogic;

  -- read-back data buses --

  signal rom_rdata       : std_ulogic_vector(15 downto 0);

  signal ram_rdata       : std_ulogic_vector(15 downto 0);

  signal muldiv_rdata    : std_ulogic_vector(15 downto 0);

  signal wb_rdata        : std_ulogic_vector(15 downto 0);

  signal boot_rdata      : std_ulogic_vector(15 downto 0);

  signal wdt_rdata       : std_ulogic_vector(15 downto 0);

  signal timer_rdata     : std_ulogic_vector(15 downto 0);

  signal uart_rdata      : std_ulogic_vector(15 downto 0);

  signal spi_rdata       : std_ulogic_vector(15 downto 0);

  signal gpio_rdata      : std_ulogic_vector(15 downto 0);

  signal crc_rdata       : std_ulogic_vector(15 downto 0);

  signal cfu_rdata       : std_ulogic_vector(15 downto 0);

  signal pwm_rdata       : std_ulogic_vector(15 downto 0);

  signal twi_rdata       : std_ulogic_vector(15 downto 0);

  signal trng_rdata      : std_ulogic_vector(15 downto 0);

  signal exirq_rdata     : std_ulogic_vector(15 downto 0);

  signal freq_gen_rdata  : std_ulogic_vector(15 downto 0);

  signal sysconfig_rdata : std_ulogic_vector(15 downto 0);

  -- interrupt system --

  signal irq       : std_ulogic_vector(03 downto 0);

  signal timer_irq : std_ulogic;

  signal uart_irq  : std_ulogic;

  signal spi_irq   : std_ulogic;

  signal twi_irq   : std_ulogic;

  signal gpio_irq  : std_ulogic;

  signal ext_irq   : std_ulogic;

  -- misc --

  signal imem_up_en : std_ulogic;

  signal gpio_pwm   : std_ulogic;

begin

  -- Reset Generator ----------------------------------------------------------

  -- -----------------------------------------------------------------------------

  -- make sure the external reset is free of metastability and has a minimal duration of 1 clock cycle

  reset_generator_filter: process(clk_i)

  begin

    if rising_edge(clk_i) then

      rst_i_sync0 <= rst_i;

      rst_i_sync1 <= rst_i_sync0; -- no metastability, thanks

    end if;

  end process reset_generator_filter;

  -- keep internal reset active for at least 4 clock cycles

  reset_generator: process(rst_i_sync1, clk_i)

  begin

    if rising_edge(clk_i) then

      if (rst_i_sync1 = '0') then

        rst_gen <= (others => '0');

      else

        rst_gen <= rst_gen(rst_gen'left-1 downto 0) & '1';

      end if;

    end if;

  end process reset_generator;

  ext_rst <= rst_gen(rst_gen'left); -- the beautified external reset signal

  sys_rst <= ext_rst and wdt_rst;

  -- Clock Generator ----------------------------------------------------------

  -- -----------------------------------------------------------------------------

  clock_generator: process(sys_rst, clk_i)

  begin

    if (sys_rst = '0') then

      clk_div <= (others => '0');

    elsif rising_edge(clk_i) then

      -- anybody needing fresh clocks?

      if ((timer_cg_en or uart_cg_en or spi_cg_en or wdt_cg_en or pwm_cg_en or twi_cg_en or cfu_cg_en or freq_gen_cg_en) = '1') then

        clk_div <= std_ulogic_vector(unsigned(clk_div) + 1);

      end if;

    end if;

  end process clock_generator;

  clock_generator_buf: process(clk_i)

  begin

    if rising_edge(clk_i) then

      clk_div_ff <= clk_div;

    end if;

  end process clock_generator_buf;

  -- clock enable select: rising edge detectors --

  clk_gen(clk_div2_c)    <= clk_div(0)  and (not clk_div_ff(0));  -- CLK/2

  clk_gen(clk_div4_c)    <= clk_div(1)  and (not clk_div_ff(1));  -- CLK/4

  clk_gen(clk_div8_c)    <= clk_div(2)  and (not clk_div_ff(2));  -- CLK/8

  clk_gen(clk_div64_c)   <= clk_div(5)  and (not clk_div_ff(5));  -- CLK/64

  clk_gen(clk_div128_c)  <= clk_div(6)  and (not clk_div_ff(6));  -- CLK/128

  clk_gen(clk_div1024_c) <= clk_div(9)  and (not clk_div_ff(9));  -- CLK/1024

  clk_gen(clk_div2048_c) <= clk_div(10) and (not clk_div_ff(10)); -- CLK/2048

  clk_gen(clk_div4096_c) <= clk_div(11) and (not clk_div_ff(11)); -- CLK/4096

  -- The core of the problem: The CPU -----------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_cpu_inst: neo430_cpu

  generic map (

    BOOTLD_USE  => BOOTLD_USE,      -- implement and use bootloader? (default=true)

    IMEM_AS_ROM => IMEM_AS_ROM      -- implement IMEM as read-only memory?

  )

  port map (

    -- global control --

    clk_i      => clk_i,            -- global clock, rising edge

    rst_i      => sys_rst,          -- global reset, low-active, async

    -- memory interface --

    mem_rd_o   => cpu_bus.rd_en,    -- memory read

    mem_imwe_o => imem_up_en,       -- allow writing to IMEM

    mem_wr_o   => cpu_bus.wr_en,    -- memory write

    mem_addr_o => cpu_bus.addr,     -- address

    mem_data_o => cpu_bus.wdata,    -- write data

    mem_data_i => cpu_bus.rdata,    -- read data

    -- interrupt system --

    irq_i      => irq              -- interrupt request lines

  );

  -- final CPU read data --

  cpu_bus.rdata <= rom_rdata or ram_rdata or boot_rdata or muldiv_rdata or

                   wb_rdata or uart_rdata or spi_rdata or gpio_rdata or freq_gen_rdata or

                   timer_rdata or wdt_rdata or sysconfig_rdata or crc_rdata or

                   cfu_rdata or pwm_rdata or twi_rdata or trng_rdata or exirq_rdata;

  -- interrupts: priority assignment --

  irq(0) <= timer_irq;                      -- timer match (highest priority)

  irq(1) <= uart_irq or spi_irq or twi_irq; -- serial IRQ

  irq(2) <= gpio_irq;                       -- GPIO input pin change

  irq(3) <= ext_irq;                        -- external interrupt request (lowest priority)

  -- Main Memory (ROM/IMEM & RAM/DMEM) ----------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_imem_inst: neo430_imem

  generic map (

    IMEM_SIZE   => IMEM_SIZE,       -- internal IMEM size in bytes, max 32kB (default=4kB)

    IMEM_AS_ROM => IMEM_AS_ROM,     -- implement IMEM as read-only memory?

    BOOTLD_USE  => BOOTLD_USE       -- implement and use bootloader? (default=true)

  )

  port map (

    clk_i  => clk_i,                -- global clock line

    rden_i => cpu_bus.rd_en,        -- read enable

    wren_i => cpu_bus.wr_en,        -- write enable

    upen_i => imem_up_en,           -- update enable

    addr_i => cpu_bus.addr,         -- address

    data_i => cpu_bus.wdata,        -- data in

    data_o => rom_rdata             -- data out

  );

  neo430_dmem_inst: neo430_dmem

  generic map (

    DMEM_SIZE => DMEM_SIZE          -- internal DMEM size in bytes, max 28kB (default=2kB)

  )

  port map (

    clk_i  => clk_i,                -- global clock line

    rden_i => cpu_bus.rd_en,        -- read enable

    wren_i => cpu_bus.wr_en,        -- write enable

    addr_i => cpu_bus.addr,         -- address

    data_i => cpu_bus.wdata,        -- data in

    data_o => ram_rdata             -- data out

  );

  -- Boot ROM -----------------------------------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_boot_rom_inst_true:

  if (BOOTLD_USE = true) generate

    neo430_boot_rom_inst: neo430_boot_rom

    port map (

      clk_i  => clk_i,              -- global clock line

      rden_i => cpu_bus.rd_en,      -- read enable

      addr_i => cpu_bus.addr,       -- address

      data_o => boot_rdata          -- data out

    );

  end generate;

  neo430_boot_rom_inst_false:

  if (BOOTLD_USE = false) generate

    boot_rdata <= (others => '0');

  end generate;

  -- IO Access? ---------------------------------------------------------------

  -- -----------------------------------------------------------------------------

  io_acc   <= '1' when (cpu_bus.addr(15 downto index_size_f(io_size_c)) = io_base_c(15 downto index_size_f(io_size_c))) else '0';

  io_rd_en <= cpu_bus.rd_en and io_acc;

  io_wr_en <= (cpu_bus.wr_en(0) or cpu_bus.wr_en(1)) and io_acc; -- use all accesses as full-word accesses

  -- Multiplier/Divider Unit (MULDIV) -----------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_muldiv_inst_true:

  if (MULDIV_USE = true) generate

    neo430_muldiv_inst: neo430_muldiv

    port map (

      -- host access --

      clk_i  => clk_i,              -- global clock line

      rden_i => io_rd_en,           -- read enable

      wren_i => io_wr_en,           -- write enable

      addr_i => cpu_bus.addr,       -- address

      data_i => cpu_bus.wdata,      -- data in

      data_o => muldiv_rdata        -- data out

    );

  end generate;

  neo430_muldiv_inst_false:

  if (MULDIV_USE = false) generate

    muldiv_rdata <= (others => '0');

  end generate;

  -- Wishbone Adapter (WB32) --------------------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_wb32_if_inst_true:

  if (WB32_USE = true) generate

    neo430_wb32_inst: neo430_wb_interface

    port map (

      -- host access --

      clk_i    => clk_i,            -- global clock line

      rden_i   => io_rd_en,         -- read enable

      wren_i   => io_wr_en,         -- write enable

      addr_i   => cpu_bus.addr,     -- address

      data_i   => cpu_bus.wdata,    -- data in

      data_o   => wb_rdata,         -- data out

      -- wishbone interface --

      wb_adr_o => wb_adr_o,         -- address

      wb_dat_i => wb_dat_i,         -- read data

      wb_dat_o => wb_dat_o,         -- write data

      wb_we_o  => wb_we_o,          -- read/write

      wb_sel_o => wb_sel_o,         -- byte enable

      wb_stb_o => wb_stb_o,         -- strobe

      wb_cyc_o => wb_cyc_o,         -- valid cycle

      wb_ack_i => wb_ack_i          -- transfer acknowledge

    );

  end generate;

  neo430_wb32_if_inst_false:

  if (WB32_USE = false) generate

    wb_rdata <= (others => '0');

    wb_adr_o <= (others => '0');

    wb_dat_o <= (others => '0');

    wb_we_o  <= '0';

    wb_sel_o <= (others => '0');

    wb_stb_o <= '0';

    wb_cyc_o <= '0';

  end generate;

  -- Universal Asynchronous Receiver & Transmitter (UART) ---------------------

  -- -----------------------------------------------------------------------------

  neo430_uart_inst_true:

  if (UART_USE = true) generate

    neo430_uart_inst: neo430_uart

    port map (

      -- host access --

      clk_i       => clk_i,         -- global clock line

      rden_i      => io_rd_en,      -- read enable

      wren_i      => io_wr_en,      -- write enable

      addr_i      => cpu_bus.addr,  -- address

      data_i      => cpu_bus.wdata, -- data in

      data_o      => uart_rdata,    -- data out

      -- clock generator --

      clkgen_en_o => uart_cg_en,    -- enable clock generator

      clkgen_i    => clk_gen,

      -- com lines --

      uart_txd_o  => uart_txd_o,

      uart_rxd_i  => uart_rxd_i,

      -- interrupts --

      uart_irq_o  => uart_irq       -- uart rx/tx interrupt

    );

  end generate;

  neo430_uart_inst_false:

  if (UART_USE = false) generate

    uart_rdata <= (others => '0');

    uart_irq   <= '0';

    uart_cg_en <= '0';

    uart_txd_o <= '1';

  end generate;

  -- Serial Peripheral Interface (SPI) ----------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_spi_inst_true:

  if (SPI_USE = true) generate

    neo430_spi_inst: neo430_spi

    port map (

      -- host access --

      clk_i       => clk_i,         -- global clock line

      rden_i      => io_rd_en,      -- read enable

      wren_i      => io_wr_en,      -- write enable

      addr_i      => cpu_bus.addr,  -- address

      data_i      => cpu_bus.wdata, -- data in

      data_o      => spi_rdata,     -- data out

      -- clock generator --

      clkgen_en_o => spi_cg_en,     -- enable clock generator

      clkgen_i    => clk_gen,

      -- com lines --

      spi_sclk_o  => spi_sclk_o,    -- SPI serial clock

      spi_mosi_o  => spi_mosi_o,    -- SPI master out, slave in

      spi_miso_i  => spi_miso_i,    -- SPI master in, slave out

      spi_cs_o    => spi_cs_o,      -- SPI CS 0..5

      -- interrupt --

      spi_irq_o   => spi_irq        -- transmission done interrupt

    );

  end generate;

  neo430_spi_inst_false:

  if (SPI_USE = false) generate

    spi_rdata  <= (others => '0');

    spi_cg_en  <= '0';

    spi_sclk_o <= '0';

    spi_mosi_o <= '0';

    spi_cs_o   <= (others => '1');

    spi_irq    <= '0';

  end generate;

  -- General Purpose Parallel IO (GPIO) ---------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_gpio_inst_true:

  if (GPIO_USE = true) generate

    neo430_gpio_inst: neo430_gpio

    port map (

      -- host access --

      clk_i      => clk_i,          -- global clock line

      rden_i     => io_rd_en,       -- read enable

      wren_i     => io_wr_en,       -- write enable

      addr_i     => cpu_bus.addr,   -- address

      data_i     => cpu_bus.wdata,  -- data in

      data_o     => gpio_rdata,     -- data out

      -- parallel io --

      gpio_o     => gpio_o,

      gpio_i     => gpio_i,

     -- GPIO PWM --

      gpio_pwm_i => gpio_pwm,

      -- interrupt --

      irq_o      => gpio_irq        -- pin-change interrupt

    );

  end generate;

  neo430_gpio_inst_false:

  if (GPIO_USE = false) generate

    gpio_rdata <= (others => '0');

    gpio_o     <= (others => '0');

    gpio_irq   <= '0';

  end generate;

  -- High Precision Timer (TIMER) ---------------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_timer_inst_true:

  if (TIMER_USE = true) generate

  neo430_timer_inst: neo430_timer

    port map (

      -- host access --

      clk_i       => clk_i,         -- global clock line

      rden_i      => io_rd_en,      -- read enable

      wren_i      => io_wr_en,      -- write enable

      addr_i      => cpu_bus.addr,  -- address

      data_i      => cpu_bus.wdata, -- data in

      data_o      => timer_rdata,   -- data out

      -- clock generator --

      clkgen_en_o => timer_cg_en,   -- enable clock generator

      clkgen_i    => clk_gen,

      -- interrupt --

      irq_o       => timer_irq      -- interrupt request

    );

  end generate;

  neo430_timer_inst_false:

  if (TIMER_USE = false) generate

    timer_rdata <= (others => '0');

    timer_irq   <= '0';

    timer_cg_en <= '0';

  end generate;

  -- Watchdog Timer (WDT) -----------------------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_wdt_inst_true:

  if (WDT_USE = true) generate

    neo430_wdt_inst: neo430_wdt

    port map(

      -- host access --

      clk_i       => clk_i,         -- global clock line

      rst_i       => ext_rst,       -- external reset, low-active, use as async

      rden_i      => io_rd_en,      -- read enable

      wren_i      => io_wr_en,      -- write enable

      addr_i      => cpu_bus.addr,  -- address

      data_i      => cpu_bus.wdata, -- data in

      data_o      => wdt_rdata,     -- data out

      -- clock generator --

      clkgen_en_o => wdt_cg_en,     -- enable clock generator

      clkgen_i    => clk_gen,       -- clock generator

      -- system reset --

      rst_o       => wdt_rst        -- timeout reset, low-active, use as async

    );

  end generate;

  neo430_wdt_inst_false:

  if (WDT_USE = false) generate

    wdt_rdata <= (others => '0');

    wdt_rst   <= '1';

    wdt_cg_en <= '0';

  end generate;

  -- Checksum Module (CRC) ----------------------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_crc_inst_true:

  if (CRC_USE = true) generate

    neo430_crc_inst: neo430_crc

    port map(

      -- host access --

      clk_i  => clk_i,              -- global clock line

      rden_i => io_rd_en,           -- read enable

      wren_i => io_wr_en,           -- write enable

      addr_i => cpu_bus.addr,       -- address

      data_i => cpu_bus.wdata,      -- data in

      data_o => crc_rdata           -- data out

    );

  end generate;

  neo430_crc_inst_false:

  if (CRC_USE = false) generate

    crc_rdata <= (others => '0');

  end generate;

  -- Custom Functions Unit (CFU) ----------------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_cfu_inst_true:

  if (CFU_USE = true) generate

    neo430_cfu_inst: neo430_cfu

    port map(

      -- host access --

      clk_i       => clk_i,         -- global clock line

      rden_i      => io_rd_en,      -- read enable

      wren_i      => io_wr_en,      -- write enable

      addr_i      => cpu_bus.addr,  -- address

      data_i      => cpu_bus.wdata, -- data in

      data_o      => cfu_rdata,     -- data out

      -- clock generator --

      clkgen_en_o => cfu_cg_en,     -- enable clock generator

      clkgen_i    => clk_gen

      -- add custom IOs below --

    );

  end generate;

  neo430_cfu_inst_false:

  if (CFU_USE = false) generate

    cfu_cg_en <= '0';

    cfu_rdata <= (others => '0');

  end generate;

  -- PWM Controller (PWM) -----------------------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_pwm_inst_true:

  if (PWM_USE = true) generate

    neo430_pwm_inst: neo430_pwm

    port map(

      -- host access --

      clk_i       => clk_i,         -- global clock line

      rden_i      => io_rd_en,      -- read enable

      wren_i      => io_wr_en,      -- write enable

      addr_i      => cpu_bus.addr,  -- address

      data_i      => cpu_bus.wdata, -- data in

      data_o      => pwm_rdata,     -- data out

      -- clock generator --

      clkgen_en_o => pwm_cg_en,     -- enable clock generator

      clkgen_i    => clk_gen,

      -- GPIO output PWM --

      gpio_pwm_o  => gpio_pwm,

      -- pwm output channels --

      pwm_o       => pwm_o

    );

  end generate;

  neo430_pwm_inst_false:

  if (PWM_USE = false) generate

    pwm_cg_en <= '0';

    gpio_pwm  <= '1';

    pwm_rdata <= (others => '0');

    pwm_o     <= (others => '0');

  end generate;

  -- Two Wire Serial Interface (SPI) ------------------------------------------

  -- -----------------------------------------------------------------------------

  neo430_twi_inst_true:

  if (TWI_USE = true) generate

    neo430_twi_inst: neo430_twi

    port map (

      -- host access --

      clk_i       => clk_i,         -- global clock line

      rden_i      => io_rd_en,      -- read enable

      wren_i      => io_wr_en,      -- write enable

      addr_i      => cpu_bus.addr,  -- address

      data_i      => cpu_bus.wdata, -- data in

      data_o      => twi_rdata,     -- data out

      -- clock generator --

      clkgen_en_o => twi_cg_en,     -- enable clock generator