Subversion Repositories neorv32

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

-- # << NEORV32 - Processor Top Entity with AXI4-Lite Compatible Master Interface >>               #

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

-- # (c) "AXI", "AXI4" and "AXI4-Lite" are trademarks of Arm Holdings plc.                         #

-- # Note: External MTIME is not supported.                                                        #

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

-- # BSD 3-Clause License                                                                          #

-- #                                                                                               #

-- # Copyright (c) 2021, 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               #

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-- # OF THE POSSIBILITY OF SUCH DAMAGE.                                                            #

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

-- # The NEORV32 Processor - https://github.com/stnolting/neorv32              (c) Stephan Nolting #

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

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

library neorv32;

use neorv32.neorv32_package.all;

entity neorv32_SystemTop_axi4lite is

  generic (

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

    -- Configuration Generics --

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

    -- General --

    CLOCK_FREQUENCY              : natural := 0;      -- clock frequency of clk_i in Hz

    INT_BOOTLOADER_EN            : boolean := true;   -- boot configuration: true = boot explicit bootloader; false = boot from int/ext (I)MEM

    HW_THREAD_ID                 : natural := 0;      -- hardware thread id (32-bit)

    -- On-Chip Debugger (OCD) --

    ON_CHIP_DEBUGGER_EN          : boolean := false;  -- implement on-chip debugger

    -- RISC-V CPU Extensions --

    CPU_EXTENSION_RISCV_A        : boolean := false;  -- implement atomic extension?

    CPU_EXTENSION_RISCV_B        : boolean := false;  -- implement bit-manipulation extension?

    CPU_EXTENSION_RISCV_C        : boolean := false;  -- implement compressed extension?

    CPU_EXTENSION_RISCV_E        : boolean := false;  -- implement embedded RF extension?

    CPU_EXTENSION_RISCV_M        : boolean := false;  -- implement muld/div extension?

    CPU_EXTENSION_RISCV_U        : boolean := false;  -- implement user mode extension?

    CPU_EXTENSION_RISCV_Zfinx    : boolean := false;  -- implement 32-bit floating-point extension (using INT reg!)

    CPU_EXTENSION_RISCV_Zicsr    : boolean := true;   -- implement CSR system?

    CPU_EXTENSION_RISCV_Zicntr   : boolean := true;   -- implement base counters?

    CPU_EXTENSION_RISCV_Zihpm    : boolean := false;  -- implement hardware performance monitors?

    CPU_EXTENSION_RISCV_Zifencei : boolean := false;  -- implement instruction stream sync.?

    -- Extension Options --

    FAST_MUL_EN                  : boolean := false;  -- use DSPs for M extension's multiplier

    FAST_SHIFT_EN                : boolean := false;  -- use barrel shifter for shift operations

    CPU_CNT_WIDTH                : natural := 64;     -- total width of CPU cycle and instret counters (0..64)

    -- Physical Memory Protection (PMP) --

    PMP_NUM_REGIONS              : natural := 0;      -- number of regions (0..64)

    PMP_MIN_GRANULARITY          : natural := 64*1024; -- minimal region granularity in bytes, has to be a power of 2, min 8 bytes

    -- Hardware Performance Monitors (HPM) --

    HPM_NUM_CNTS                 : natural := 0;      -- number of implemented HPM counters (0..29)

    HPM_CNT_WIDTH                : natural := 40;     -- total size of HPM counters (0..64)

    -- Internal Instruction memory --

    MEM_INT_IMEM_EN              : boolean := true;   -- implement processor-internal instruction memory

    MEM_INT_IMEM_SIZE            : natural := 16*1024; -- size of processor-internal instruction memory in bytes

    -- Internal Data memory --

    MEM_INT_DMEM_EN              : boolean := true;   -- implement processor-internal data memory

    MEM_INT_DMEM_SIZE            : natural := 8*1024; -- size of processor-internal data memory in bytes

    -- Internal Cache memory --

    ICACHE_EN                    : boolean := false;  -- implement instruction cache

    ICACHE_NUM_BLOCKS            : natural := 4;      -- i-cache: number of blocks (min 1), has to be a power of 2

    ICACHE_BLOCK_SIZE            : natural := 64;     -- i-cache: block size in bytes (min 4), has to be a power of 2

    ICACHE_ASSOCIATIVITY         : natural := 1;      -- i-cache: associativity / number of sets (1=direct_mapped), has to be a power of 2

    -- External Interrupts Controller (XIRQ) --

    XIRQ_NUM_CH                  : natural := 0;      -- number of external IRQ channels (0..32)

    XIRQ_TRIGGER_TYPE            : std_logic_vector(31 downto 0) := x"FFFFFFFF"; -- trigger type: 0=level, 1=edge

    XIRQ_TRIGGER_POLARITY        : std_logic_vector(31 downto 0) := x"FFFFFFFF"; -- trigger polarity: 0=low-level/falling-edge, 1=high-level/rising-edge

    -- Processor peripherals --

    IO_GPIO_EN                   : boolean := true;   -- implement general purpose input/output port unit (GPIO)?

    IO_MTIME_EN                  : boolean := true;   -- implement machine system timer (MTIME)?

    IO_UART0_EN                  : boolean := true;   -- implement primary universal asynchronous receiver/transmitter (UART0)?

    IO_UART0_RX_FIFO             : natural := 1;      -- RX fifo depth, has to be a power of two, min 1

    IO_UART0_TX_FIFO             : natural := 1;      -- TX fifo depth, has to be a power of two, min 1

    IO_UART1_EN                  : boolean := true;   -- implement secondary universal asynchronous receiver/transmitter (UART1)?

    IO_UART1_RX_FIFO             : natural := 1;      -- RX fifo depth, has to be a power of two, min 1

    IO_UART1_TX_FIFO             : natural := 1;      -- TX fifo depth, has to be a power of two, min 1

    IO_SPI_EN                    : boolean := true;   -- implement serial peripheral interface (SPI)?

    IO_TWI_EN                    : boolean := true;   -- implement two-wire interface (TWI)?

    IO_PWM_NUM_CH                : natural := 4;      -- number of PWM channels to implement (0..60); 0 = disabled

    IO_WDT_EN                    : boolean := true;   -- implement watch dog timer (WDT)?

    IO_TRNG_EN                   : boolean := false;  -- implement true random number generator (TRNG)?

    IO_CFS_EN                    : boolean := false;  -- implement custom functions subsystem (CFS)?

    IO_CFS_CONFIG                : std_logic_vector(31 downto 0) := x"00000000"; -- custom CFS configuration generic

    IO_CFS_IN_SIZE               : positive := 32;    -- size of CFS input conduit in bits

    IO_CFS_OUT_SIZE              : positive := 32;    -- size of CFS output conduit in bits

    IO_NEOLED_EN                 : boolean := true;   -- implement NeoPixel-compatible smart LED interface (NEOLED)?

    IO_NEOLED_TX_FIFO            : natural := 1       -- NEOLED TX FIFO depth, 1..32k, has to be a power of two

  );

  port (

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

    -- AXI4-Lite-Compatible Master Interface --

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

    -- Clock and Reset --

    m_axi_aclk    : in  std_logic;

    m_axi_aresetn : in  std_logic;

    -- Write Address Channel --

    m_axi_awaddr  : out std_logic_vector(31 downto 0);

    m_axi_awprot  : out std_logic_vector(2 downto 0);

    m_axi_awvalid : out std_logic;

    m_axi_awready : in  std_logic;

    -- Write Data Channel --

    m_axi_wdata   : out std_logic_vector(31 downto 0);

    m_axi_wstrb   : out std_logic_vector(3 downto 0);

    m_axi_wvalid  : out std_logic;

    m_axi_wready  : in  std_logic;

    -- Read Address Channel --

    m_axi_araddr  : out std_logic_vector(31 downto 0);

    m_axi_arprot  : out std_logic_vector(2 downto 0);

    m_axi_arvalid : out std_logic;

    m_axi_arready : in  std_logic;

    -- Read Data Channel --

    m_axi_rdata   : in  std_logic_vector(31 downto 0);

    m_axi_rresp   : in  std_logic_vector(1 downto 0);

    m_axi_rvalid  : in  std_logic;

    m_axi_rready  : out std_logic;

    -- Write Response Channel --

    m_axi_bresp   : in  std_logic_vector(1 downto 0);

    m_axi_bvalid  : in  std_logic;

    m_axi_bready  : out std_logic;

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

    -- JTAG on-chip debugger interface (available if ON_CHIP_DEBUGGER_EN = true) --

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

    jtag_trst_i   : in  std_logic := '0'; -- low-active TAP reset (optional)

    jtag_tck_i    : in  std_logic := '0'; -- serial clock

    jtag_tdi_i    : in  std_logic := '0'; -- serial data input

    jtag_tdo_o    : out std_logic;        -- serial data output

    jtag_tms_i    : in  std_logic := '0'; -- mode select

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

    -- Processor IO --

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

    -- GPIO (available if IO_GPIO_EN = true) --

    gpio_o        : out std_logic_vector(63 downto 0); -- parallel output

    gpio_i        : in  std_logic_vector(63 downto 0) := (others => '0'); -- parallel input

    -- primary UART0 (available if IO_UART0_EN = true) --

    uart0_txd_o   : out std_logic; -- UART0 send data

    uart0_rxd_i   : in  std_logic := '0'; -- UART0 receive data

    uart0_rts_o   : out std_logic; -- hw flow control: UART0.RX ready to receive ("RTR"), low-active, optional

    uart0_cts_i   : in  std_logic := '0'; -- hw flow control: UART0.TX allowed to transmit, low-active, optional

    -- secondary UART1 (available if IO_UART1_EN = true) --

    uart1_txd_o   : out std_logic; -- UART1 send data

    uart1_rxd_i   : in  std_logic := '0'; -- UART1 receive data

    uart1_rts_o   : out std_logic; -- hw flow control: UART1.RX ready to receive ("RTR"), low-active, optional

    uart1_cts_i   : in  std_logic := '0'; -- hw flow control: UART1.TX allowed to transmit, low-active, optional

    -- SPI (available if IO_SPI_EN = true) --

    spi_sck_o     : out std_logic; -- SPI serial clock

    spi_sdo_o     : out std_logic; -- controller data out, peripheral data in

    spi_sdi_i     : in  std_logic := '0'; -- controller data in, peripheral data out

    spi_csn_o     : out std_logic_vector(07 downto 0); -- SPI CS

    -- TWI (available if IO_TWI_EN = true) --

    twi_sda_io    : inout std_logic; -- twi serial data line

    twi_scl_io    : inout std_logic; -- twi serial clock line

    -- PWM (available if IO_PWM_NUM_CH > 0) --

    pwm_o         : out std_logic_vector(IO_PWM_NUM_CH-1 downto 0);  -- pwm channels

    -- Custom Functions Subsystem IO (available if IO_CFS_EN = true) --

    cfs_in_i      : in  std_logic_vector(IO_CFS_IN_SIZE-1  downto 0); -- custom inputs

    cfs_out_o     : out std_logic_vector(IO_CFS_OUT_SIZE-1 downto 0); -- custom outputs

    -- NeoPixel-compatible smart LED interface (available if IO_NEOLED_EN = true) --

    neoled_o      : out std_logic; -- async serial data line

    -- External platform interrupts (available if XIRQ_NUM_CH > 0) --

    xirq_i        : in  std_logic_vector(XIRQ_NUM_CH-1 downto 0) := (others => '0'); -- IRQ channels

    -- CPU Interrupts --

    msw_irq_i     : in  std_logic := '0'; -- machine software interrupt

    mext_irq_i    : in  std_logic := '0'  -- machine external interrupt

  );

end entity;

architecture neorv32_SystemTop_axi4lite_rtl of neorv32_SystemTop_axi4lite is

  -- type conversion --

  constant IO_CFS_CONFIG_INT         : std_ulogic_vector(31 downto 0) := std_ulogic_vector(IO_CFS_CONFIG);

  constant XIRQ_TRIGGER_TYPE_INT     : std_ulogic_vector(31 downto 0) := std_ulogic_vector(XIRQ_TRIGGER_TYPE);

  constant XIRQ_TRIGGER_POLARITY_INT : std_ulogic_vector(31 downto 0) := std_ulogic_vector(XIRQ_TRIGGER_POLARITY);

  --

  signal clk_i_int       : std_ulogic;

  signal rstn_i_int      : std_ulogic;

  --

  signal jtag_trst_i_int :std_ulogic;

  signal jtag_tck_i_int  :std_ulogic;

  signal jtag_tdi_i_int  :std_ulogic;

  signal jtag_tdo_o_int  :std_ulogic;

  signal jtag_tms_i_int  :std_ulogic;

  --

  signal gpio_o_int      : std_ulogic_vector(63 downto 0);

  signal gpio_i_int      : std_ulogic_vector(63 downto 0);

  --

  signal uart0_txd_o_int : std_ulogic;

  signal uart0_rxd_i_int : std_ulogic;

  signal uart0_rts_o_int : std_ulogic;

  signal uart0_cts_i_int : std_ulogic;

  --

  signal uart1_txd_o_int : std_ulogic;

  signal uart1_rxd_i_int : std_ulogic;

  signal uart1_rts_o_int : std_ulogic;

  signal uart1_cts_i_int : std_ulogic;

  --

  signal spi_sck_o_int   : std_ulogic;

  signal spi_sdo_o_int   : std_ulogic;

  signal spi_sdi_i_int   : std_ulogic;

  signal spi_csn_o_int   : std_ulogic_vector(07 downto 0);

  --

  signal pwm_o_int       : std_ulogic_vector(IO_PWM_NUM_CH-1 downto 0);

  --

  signal cfs_in_i_int    : std_ulogic_vector(IO_CFS_IN_SIZE-1  downto 0);

  signal cfs_out_o_int   : std_ulogic_vector(IO_CFS_OUT_SIZE-1 downto 0);

  --

  signal neoled_o_int    : std_ulogic;

  --

  signal xirq_i_int      : std_ulogic_vector(XIRQ_NUM_CH-1 downto 0);

  --

  signal msw_irq_i_int   : std_ulogic;

  signal mext_irq_i_int  : std_ulogic;

  -- internal wishbone bus --

  type wb_bus_t is record

    adr  : std_ulogic_vector(31 downto 0); -- address

    di   : std_ulogic_vector(31 downto 0); -- processor input data

    do   : std_ulogic_vector(31 downto 0); -- processor output data

    we   : std_ulogic; -- write enable

    sel  : std_ulogic_vector(03 downto 0); -- byte enable

    stb  : std_ulogic; -- strobe

    cyc  : std_ulogic; -- valid cycle

    ack  : std_ulogic; -- transfer acknowledge

    err  : std_ulogic; -- transfer error

    tag  : std_ulogic_vector(02 downto 0); -- tag

    lock : std_ulogic; -- exclusive access request

  end record;

  signal wb_core : wb_bus_t;

  -- AXI bridge control --

  type ctrl_t is record

    radr_received : std_ulogic;

    wadr_received : std_ulogic;

    wdat_received : std_ulogic;

  end record;

  signal ctrl : ctrl_t;

  signal ack_read, ack_write : std_ulogic; -- normal transfer termination

  signal err_read, err_write : std_ulogic; -- error transfer termination

begin

  -- Sanity Checks --------------------------------------------------------------------------

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

  assert not (CPU_EXTENSION_RISCV_A = true) report "NEORV32 PROCESSOR CONFIG WARNING: AXI4-Lite provides NO support for atomic memory operations. LR/SC access via AXI will raise a bus exception." severity warning;

  -- The Core Of The Problem ----------------------------------------------------------------

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

  neorv32_top_inst: neorv32_top

  generic map (

    -- General --

    CLOCK_FREQUENCY              => CLOCK_FREQUENCY,    -- clock frequency of clk_i in Hz

    INT_BOOTLOADER_EN            => INT_BOOTLOADER_EN,  -- boot configuration: true = boot explicit bootloader; false = boot from int/ext (I)MEM

    HW_THREAD_ID                 => HW_THREAD_ID,       -- hardware thread id (hartid)

    -- On-Chip Debugger (OCD) --

    ON_CHIP_DEBUGGER_EN          => ON_CHIP_DEBUGGER_EN,          -- implement on-chip debugger

    -- RISC-V CPU Extensions --

    CPU_EXTENSION_RISCV_A        => CPU_EXTENSION_RISCV_A,        -- implement atomic extension?

    CPU_EXTENSION_RISCV_B        => CPU_EXTENSION_RISCV_B,        -- implement bit-manipulation extension?

    CPU_EXTENSION_RISCV_C        => CPU_EXTENSION_RISCV_C,        -- implement compressed extension?

    CPU_EXTENSION_RISCV_E        => CPU_EXTENSION_RISCV_E,        -- implement embedded RF extension?

    CPU_EXTENSION_RISCV_M        => CPU_EXTENSION_RISCV_M,        -- implement muld/div extension?

    CPU_EXTENSION_RISCV_U        => CPU_EXTENSION_RISCV_U,        -- implement user mode extension?

    CPU_EXTENSION_RISCV_Zfinx    => CPU_EXTENSION_RISCV_Zfinx,    -- implement 32-bit floating-point extension (using INT reg!)

    CPU_EXTENSION_RISCV_Zicsr    => CPU_EXTENSION_RISCV_Zicsr,    -- implement CSR system?

    CPU_EXTENSION_RISCV_Zicntr   => CPU_EXTENSION_RISCV_Zicntr,   -- implement base counters?

    CPU_EXTENSION_RISCV_Zihpm    => CPU_EXTENSION_RISCV_Zihpm,    -- implement hardware performance monitors?

    CPU_EXTENSION_RISCV_Zifencei => CPU_EXTENSION_RISCV_Zifencei, -- implement instruction stream sync.?

    -- Extension Options --

    FAST_MUL_EN                  => FAST_MUL_EN,        -- use DSPs for M extension's multiplier

    FAST_SHIFT_EN                => FAST_SHIFT_EN,      -- use barrel shifter for shift operations

    CPU_CNT_WIDTH                => CPU_CNT_WIDTH,      -- total width of CPU cycle and instret counters (0..64)

    -- Physical Memory Protection (PMP) --

    PMP_NUM_REGIONS              => PMP_NUM_REGIONS,    -- number of regions (0..64)

    PMP_MIN_GRANULARITY          => PMP_MIN_GRANULARITY, -- minimal region granularity in bytes, has to be a power of 2, min 8 bytes

    -- Hardware Performance Monitors (HPM) --

    HPM_NUM_CNTS                 => HPM_NUM_CNTS,       -- number of implemented HPM counters (0..29)

    HPM_CNT_WIDTH                => HPM_CNT_WIDTH,      -- total size of HPM counters (0..64)

    -- Internal Instruction memory --

    MEM_INT_IMEM_EN              => MEM_INT_IMEM_EN,    -- implement processor-internal instruction memory

    MEM_INT_IMEM_SIZE            => MEM_INT_IMEM_SIZE,  -- size of processor-internal instruction memory in bytes

    -- Internal Data memory --

    MEM_INT_DMEM_EN              => MEM_INT_DMEM_EN,    -- implement processor-internal data memory

    MEM_INT_DMEM_SIZE            => MEM_INT_DMEM_SIZE,  -- size of processor-internal data memory in bytes

    -- Internal Cache memory --

    ICACHE_EN                    => ICACHE_EN,          -- implement instruction cache

    ICACHE_NUM_BLOCKS            => ICACHE_NUM_BLOCKS,  -- i-cache: number of blocks (min 1), has to be a power of 2

    ICACHE_BLOCK_SIZE            => ICACHE_BLOCK_SIZE,  -- i-cache: block size in bytes (min 4), has to be a power of 2

    ICACHE_ASSOCIATIVITY         => ICACHE_ASSOCIATIVITY, -- i-cache: associativity / number of sets (1=direct_mapped), has to be a power of 2

    -- External memory interface --

    MEM_EXT_EN                   => true,               -- implement external memory bus interface?

    MEM_EXT_TIMEOUT              => 0,                  -- cycles after a pending bus access auto-terminates (0 = disabled)

    MEM_EXT_PIPE_MODE            => false,              -- protocol: false=classic/standard wishbone mode, true=pipelined wishbone mode

    MEM_EXT_BIG_ENDIAN           => false,              -- byte order: true=big-endian, false=little-endian

    MEM_EXT_ASYNC_RX             => false,              -- use register buffer for RX data when false

    -- External Interrupts Controller (XIRQ) --

    XIRQ_NUM_CH                  => XIRQ_NUM_CH, -- number of external IRQ channels (0..32)

    XIRQ_TRIGGER_TYPE            => XIRQ_TRIGGER_TYPE_INT, -- trigger type: 0=level, 1=edge

    XIRQ_TRIGGER_POLARITY        => XIRQ_TRIGGER_POLARITY_INT, -- trigger polarity: 0=low-level/falling-edge, 1=high-level/rising-edge

    -- Processor peripherals --

    IO_GPIO_EN                   => IO_GPIO_EN,         -- implement general purpose input/output port unit (GPIO)?

    IO_MTIME_EN                  => IO_MTIME_EN,        -- implement machine system timer (MTIME)?

    IO_UART0_EN                  => IO_UART0_EN,        -- implement primary universal asynchronous receiver/transmitter (UART0)?

    IO_UART0_RX_FIFO             => IO_UART0_RX_FIFO,   -- RX fifo depth, has to be a power of two, min 1

    IO_UART0_TX_FIFO             => IO_UART0_TX_FIFO,   -- TX fifo depth, has to be a power of two, min 1

    IO_UART1_EN                  => IO_UART1_EN,        -- implement secondary universal asynchronous receiver/transmitter (UART1)?

    IO_UART1_RX_FIFO             => IO_UART1_RX_FIFO,   -- RX fifo depth, has to be a power of two, min 1

    IO_UART1_TX_FIFO             => IO_UART1_TX_FIFO,   -- TX fifo depth, has to be a power of two, min 1

    IO_SPI_EN                    => IO_SPI_EN,          -- implement serial peripheral interface (SPI)?

    IO_TWI_EN                    => IO_TWI_EN,          -- implement two-wire interface (TWI)?

    IO_PWM_NUM_CH                => IO_PWM_NUM_CH,      -- number of PWM channels to implement (0..60); 0 = disabled

    IO_WDT_EN                    => IO_WDT_EN,          -- implement watch dog timer (WDT)?

    IO_TRNG_EN                   => IO_TRNG_EN,         -- implement true random number generator (TRNG)?

    IO_CFS_EN                    => IO_CFS_EN,          -- implement custom functions subsystem (CFS)?

    IO_CFS_CONFIG                => IO_CFS_CONFIG_INT,  -- custom CFS configuration generic

    IO_CFS_IN_SIZE               => IO_CFS_IN_SIZE,     -- size of CFS input conduit in bits

    IO_CFS_OUT_SIZE              => IO_CFS_OUT_SIZE,    -- size of CFS output conduit in bits

    IO_NEOLED_EN                 => IO_NEOLED_EN,       -- implement NeoPixel-compatible smart LED interface (NEOLED)?

    IO_NEOLED_TX_FIFO            => IO_NEOLED_TX_FIFO   -- NEOLED TX FIFO depth, 1..32k, has to be a power of two

  )

  port map (

    -- Global control --

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

    rstn_i      => rstn_i_int,      -- global reset, low-active, async

    -- JTAG on-chip debugger interface (available if ON_CHIP_DEBUGGER_EN = true) --

    jtag_trst_i => jtag_trst_i_int, -- low-active TAP reset (optional)

    jtag_tck_i  => jtag_tck_i_int,  -- serial clock

    jtag_tdi_i  => jtag_tdi_i_int,  -- serial data input

    jtag_tdo_o  => jtag_tdo_o_int,  -- serial data output

    jtag_tms_i  => jtag_tms_i_int,  -- mode select

    -- Wishbone bus interface (available if MEM_EXT_EN = true) --

    wb_tag_o    => wb_core.tag,     -- tag

    wb_adr_o    => wb_core.adr,     -- address

    wb_dat_i    => wb_core.di,      -- read data

    wb_dat_o    => wb_core.do,      -- write data

    wb_we_o     => wb_core.we,      -- read/write

    wb_sel_o    => wb_core.sel,     -- byte enable

    wb_stb_o    => wb_core.stb,     -- strobe

    wb_cyc_o    => wb_core.cyc,     -- valid cycle

    wb_lock_o   => wb_core.lock,    -- exclusive access request

    wb_ack_i    => wb_core.ack,     -- transfer acknowledge

    wb_err_i    => wb_core.err,     -- transfer error

    -- Advanced memory control signals (available if MEM_EXT_EN = true) --

    fence_o     => open,            -- indicates an executed FENCE operation

    fencei_o    => open,            -- indicates an executed FENCEI operation

    -- GPIO (available if IO_GPIO_EN = true) --

    gpio_o      => gpio_o_int,      -- parallel output

    gpio_i      => gpio_i_int,      -- parallel input

    -- primary UART0 (available if IO_UART0_EN = true) --

    uart0_txd_o => uart0_txd_o_int, -- UART0 send data

    uart0_rxd_i => uart0_rxd_i_int, -- UART0 receive data

    uart0_rts_o => uart0_rts_o_int, -- hw flow control: UART0.RX ready to receive ("RTR"), low-active, optional

    uart0_cts_i => uart0_cts_i_int, -- hw flow control: UART0.TX allowed to transmit, low-active, optional

    -- secondary UART1 (available if IO_UART1_EN = true) --

    uart1_txd_o => uart1_txd_o_int, -- UART1 send data

    uart1_rxd_i => uart1_rxd_i_int, -- UART1 receive data

    uart1_rts_o => uart1_rts_o_int, -- hw flow control: UART1.RX ready to receive ("RTR"), low-active, optional

    uart1_cts_i => uart1_cts_i_int, -- hw flow control: UART1.TX allowed to transmit, low-active, optional

    -- SPI (available if IO_SPI_EN = true) --

    spi_sck_o   => spi_sck_o_int,   -- SPI serial clock

    spi_sdo_o   => spi_sdo_o_int,   -- controller data out, peripheral data in

    spi_sdi_i   => spi_sdi_i_int,   -- controller data in, peripheral data out

    spi_csn_o   => spi_csn_o_int,   -- SPI CS

    -- TWI (available if IO_TWI_EN = true) --

    twi_sda_io  => twi_sda_io,      -- twi serial data line

    twi_scl_io  => twi_scl_io,      -- twi serial clock line

    -- PWM available if IO_PWM_NUM_CH > 0) --

    pwm_o       => pwm_o_int,       -- pwm channels

    -- Custom Functions Subsystem IO (available if IO_CFS_EN = true) --

    cfs_in_i    => cfs_in_i_int,    -- custom inputs

    cfs_out_o   => cfs_out_o_int,   -- custom outputs

    -- NeoPixel-compatible smart LED interface (available if IO_NEOLED_EN = true) --

    neoled_o    => neoled_o_int,    -- async serial data line

    -- System time --

    mtime_i     => (others => '0'), -- current system time from ext. MTIME (if IO_MTIME_EN = false)

    mtime_o     => open,            -- current system time from int. MTIME (if IO_MTIME_EN = true)

    -- External platform interrupts (available if XIRQ_NUM_CH > 0) --

    xirq_i      => xirq_i_int,      -- IRQ channels

    -- CPU Interrupts --

    mtime_irq_i => '0',             -- machine timer interrupt, available if IO_MTIME_EN = false

    msw_irq_i   => msw_irq_i_int,   -- machine software interrupt

    mext_irq_i  => mext_irq_i_int   -- machine external interrupt

  );

  -- type conversion --

  gpio_o          <= std_logic_vector(gpio_o_int);

  gpio_i_int      <= std_ulogic_vector(gpio_i);

  jtag_trst_i_int <= std_ulogic(jtag_trst_i);

  jtag_tck_i_int  <= std_ulogic(jtag_tck_i);

  jtag_tdi_i_int  <= std_ulogic(jtag_tdi_i);

  jtag_tdo_o      <= std_logic(jtag_tdo_o_int);

  jtag_tms_i_int  <= std_ulogic(jtag_tms_i);

  uart0_txd_o     <= std_logic(uart0_txd_o_int);

  uart0_rxd_i_int <= std_ulogic(uart0_rxd_i);

  uart0_rts_o     <= std_logic(uart0_rts_o_int);

  uart0_cts_i_int <= std_ulogic(uart0_cts_i);

  uart1_txd_o     <= std_logic(uart1_txd_o_int);

  uart1_rxd_i_int <= std_ulogic(uart1_rxd_i);

  uart1_rts_o     <= std_logic(uart1_rts_o_int);

  uart1_cts_i_int <= std_ulogic(uart1_cts_i);

  spi_sck_o       <= std_logic(spi_sck_o_int);

  spi_sdo_o       <= std_logic(spi_sdo_o_int);

  spi_sdi_i_int   <= std_ulogic(spi_sdi_i);

  spi_csn_o       <= std_logic_vector(spi_csn_o_int);

  pwm_o           <= std_logic_vector(pwm_o_int);

  cfs_in_i_int    <= std_ulogic_vector(cfs_in_i);

  cfs_out_o       <= std_logic_vector(cfs_out_o_int);

  neoled_o        <= std_logic(neoled_o_int);

  xirq_i_int      <= std_ulogic_vector(xirq_i);

  msw_irq_i_int   <= std_ulogic(msw_irq_i);

  mext_irq_i_int  <= std_ulogic(mext_irq_i);

  -- Wishbone to AXI4-Lite Bridge -----------------------------------------------------------

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

  -- access arbiter --

  axi_access_arbiter: process(rstn_i_int, clk_i_int)

  begin

    if (rstn_i_int = '0') then

      ctrl.radr_received <= '0';

      ctrl.wadr_received <= '0';

      ctrl.wdat_received <= '0';

    elsif rising_edge(clk_i_int) then

      if (wb_core.cyc = '0') then -- idle

        ctrl.radr_received <= '0';

        ctrl.wadr_received <= '0';

        ctrl.wdat_received <= '0';

      else -- busy

        -- "read address received" flag --

        if (wb_core.we = '0') then -- pending READ

          if (m_axi_arready = '1') then -- read address received by interconnect?

            ctrl.radr_received <= '1';

          end if;

        end if;

        -- "write address received" flag --

        if (wb_core.we = '1') then -- pending WRITE

          if (m_axi_awready = '1') then -- write address received by interconnect?

            ctrl.wadr_received <= '1';

          end if;

        end if;

        -- "write data received" flag --

        if (wb_core.we = '1') then -- pending WRITE

          if (m_axi_wready = '1') then -- write data received by interconnect?

            ctrl.wdat_received <= '1';

          end if;

        end if;

      end if;

    end if;

  end process axi_access_arbiter;

  -- AXI4-Lite Global Signals --

  clk_i_int     <= std_ulogic(m_axi_aclk);

  rstn_i_int    <= std_ulogic(m_axi_aresetn);

  -- AXI4-Lite Read Address Channel --

  m_axi_araddr  <= std_logic_vector(wb_core.adr);

  m_axi_arvalid <= std_logic((wb_core.cyc and (not wb_core.we)) and (not ctrl.radr_received));

--m_axi_arprot  <= "000"; -- recommended by Xilinx

  m_axi_arprot(0) <= wb_core.tag(0); -- 0:unprivileged access, 1:privileged access

  m_axi_arprot(1) <= wb_core.tag(1); -- 0:secure access, 1:non-secure access

  m_axi_arprot(2) <= wb_core.tag(2); -- 0:data access, 1:instruction access

  -- AXI4-Lite Read Data Channel --

  m_axi_rready  <= std_logic(wb_core.cyc and (not wb_core.we));

  wb_core.di    <= std_ulogic_vector(m_axi_rdata);

  ack_read      <= std_ulogic(m_axi_rvalid);

  err_read      <= '0' when (m_axi_rresp = "00") else '1'; -- read response = ok? check this signal only when m_axi_rvalid = '1'

  -- AXI4-Lite Write Address Channel --

  m_axi_awaddr  <= std_logic_vector(wb_core.adr);

  m_axi_awvalid <= std_logic((wb_core.cyc and wb_core.we) and (not ctrl.wadr_received));

--m_axi_awprot  <= "000"; -- recommended by Xilinx

  m_axi_awprot(0) <= wb_core.tag(0); -- 0:unprivileged access, 1:privileged access

  m_axi_awprot(1) <= wb_core.tag(1); -- 0:secure access, 1:non-secure access

  m_axi_awprot(2) <= wb_core.tag(2); -- 0:data access, 1:instruction access

  -- AXI4-Lite Write Data Channel --

  m_axi_wdata   <= std_logic_vector(wb_core.do);

  m_axi_wvalid  <= std_logic((wb_core.cyc and wb_core.we) and (not ctrl.wdat_received));

  m_axi_wstrb   <= std_logic_vector(wb_core.sel); -- byte-enable

  -- AXI4-Lite Write Response Channel --

  m_axi_bready  <= std_logic(wb_core.cyc and wb_core.we);

  ack_write     <= std_ulogic(m_axi_bvalid);

  err_write     <= '0' when (m_axi_bresp = "00") else '1'; -- write response = ok? check this signal only when m_axi_bvalid = '1'

  -- Wishbone transfer termination --

  wb_core.ack   <= ack_read or ack_write;

  wb_core.err   <= (ack_read and err_read) or (ack_write and err_write) or wb_core.lock;

end architecture;