Subversion Repositories neorv32

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

-- # << NEORV32 - Simple Testbench >>                                                              #

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

-- # This testbench provides a virtual UART receiver connected to the processor's uart_txd_o       #

-- # signals. The received chars are shown in the simulator console and also written to a file     #

-- # ("neorv32.testbench_uart.out").                                                               #

-- # Futhermore, this testbench provides a simple RAM connected to the external Wishbone bus.      #

-- # The testbench configures the processor with all optional element enabled by default.          #

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

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

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

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

use ieee.math_real.all;

library neorv32;

use neorv32.neorv32_package.all;

use std.textio.all;

entity neorv32_tb is

end neorv32_tb;

architecture neorv32_tb_rtl of neorv32_tb is

  -- User Configuration ---------------------------------------------------------------------

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

  constant t_clock_c          : time := 10 ns; -- main clock period

  constant f_clock_c          : real := 100000000.0; -- main clock in Hz

  constant f_clock_nat_c      : natural := 100000000; -- main clock in Hz

  constant baud_rate_c        : real := 19200.0; -- standard UART baudrate

  constant wb_mem_base_addr_c : std_ulogic_vector(31 downto 0) := x"F0000000"; -- wishbone memory base address

  constant wb_mem_size_c      : natural := 256; -- wishbone memory size in bytes

  constant wb_mem_latency_c   : natural := 8; -- latency in clock cycles (min 1)

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

  -- text.io --

  file file_uart_tx_out : text open write_mode is "neorv32.testbench_uart.out";

  -- internal configuration --

  constant baud_val_c : real    := f_clock_c / baud_rate_c;

  constant f_clk_c    : natural := natural(f_clock_c);

  -- generators --

  signal clk_gen, rst_gen : std_ulogic := '0';

  -- simulation uart receiver --

  signal uart_txd         : std_ulogic;

  signal uart_rx_sync     : std_ulogic_vector(04 downto 0) := (others => '1');

  signal uart_rx_busy     : std_ulogic := '0';

  signal uart_rx_sreg     : std_ulogic_vector(08 downto 0) := (others => '0');

  signal uart_rx_baud_cnt : real;

  signal uart_rx_bitcnt   : natural;

  -- gpio --

  signal gpio : std_ulogic_vector(31 downto 0);

  -- twi --

  signal twi_scl, twi_sda : std_logic;

  -- spi --

  signal spi_data : std_logic;

  -- Wishbone bus --

  type wishbone_t is record

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

    wdata : std_ulogic_vector(31 downto 0); -- master write data

    rdata : std_ulogic_vector(31 downto 0); -- master read 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

  end record;

  signal wb_cpu : wishbone_t;

  -- Wishbone memory --

  type wb_mem_ram_t is array (0 to wb_mem_size_c/4-1) of std_ulogic_vector(31 downto 0);

  type wb_mem_read_latency_t is array (0 to wb_mem_latency_c-1) of std_ulogic_vector(31 downto 0);

  type wb_mem_t is record

    ram    : wb_mem_ram_t;

    rdata  : wb_mem_read_latency_t;

    acc_en : std_ulogic;

    ack    : std_ulogic_vector(wb_mem_latency_c-1 downto 0);

    rb_en  : std_ulogic_vector(wb_mem_latency_c-1 downto 0);

  end record;

  signal wb_mem : wb_mem_t;

begin

  -- Clock/Reset Generator ------------------------------------------------------------------

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

  clk_gen <= not clk_gen after (t_clock_c/2);

  rst_gen <= '0', '1' after 60*(t_clock_c/2);

  -- CPU Core -------------------------------------------------------------------------------

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

  neorv32_top_inst: neorv32_top

  generic map (

    -- General --

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

    BOOTLOADER_USE               => false,         -- implement processor-internal bootloader?

    USER_CODE                    => x"19880704",   -- custom user code

    -- RISC-V CPU Extensions --

    CPU_EXTENSION_RISCV_C        => true,          -- implement compressed extension?

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

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

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

    CPU_EXTENSION_RISCV_Zicsr    => true,          -- implement CSR system?

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

    -- Extension Options --

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

    -- Physical Memory Protection (PMP) --

    PMP_USE                      => true,          -- implement PMP?

    PMP_NUM_REGIONS              => 4,             -- number of regions (max 16)

    PMP_GRANULARITY              => 14,            -- minimal region granularity (1=8B, 2=16B, 3=32B, ...) default is 64k

    -- Internal Instruction memory --

    MEM_INT_IMEM_USE             => true,          -- implement processor-internal instruction memory

    MEM_INT_IMEM_SIZE            => 16*1024,       -- size of processor-internal instruction memory in bytes

    MEM_INT_IMEM_ROM             => false,         -- implement processor-internal instruction memory as ROM

    -- Internal Data memory --

    MEM_INT_DMEM_USE             => true,          -- implement processor-internal data memory

    MEM_INT_DMEM_SIZE            => 8*1024,        -- size of processor-internal data memory in bytes

    -- External memory interface --

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

    MEM_EXT_REG_STAGES           => 2,             -- number of interface register stages (0,1,2)

    MEM_EXT_TIMEOUT              => 15,            -- cycles after which a valid bus access will timeout

    -- Processor peripherals --

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

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

    IO_UART_USE                  => true,          -- implement universal asynchronous receiver/transmitter (UART)?

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

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

    IO_PWM_USE                   => true,          -- implement pulse-width modulation unit (PWM)?

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

    IO_TRNG_USE                  => false,         -- DEFAULT TRNG CONFIG CANNOT BE SIMULATED!

    IO_DEVNULL_USE               => true,          -- implement dummy device (DEVNULL)?

    IO_CFU_USE                   => true           -- implement custom functions unit (CFU)?

  )

  port map (

    -- Global control --

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

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

    -- Wishbone bus interface --

    wb_adr_o   => wb_cpu.addr,     -- address

    wb_dat_i   => wb_cpu.rdata,    -- read data

    wb_dat_o   => wb_cpu.wdata,    -- write data

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

    wb_sel_o   => wb_cpu.sel,      -- byte enable

    wb_stb_o   => wb_cpu.stb,      -- strobe

    wb_cyc_o   => wb_cpu.cyc,      -- valid cycle

    wb_ack_i   => wb_cpu.ack,      -- transfer acknowledge

    wb_err_i   => wb_cpu.err,      -- transfer error

    -- Advanced memory control signals --

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

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

    -- GPIO --

    gpio_o     => gpio,            -- parallel output

    gpio_i     => gpio,            -- parallel input

    -- UART --

    uart_txd_o => uart_txd,        -- UART send data

    uart_rxd_i => uart_txd,        -- UART receive data

    -- SPI --

    spi_sck_o  => open,            -- SPI serial clock

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

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

    spi_csn_o  => open,            -- SPI CS

    -- TWI --

    twi_sda_io => twi_sda,         -- twi serial data line

    twi_scl_io => twi_scl,         -- twi serial clock line

    -- PWM --

    pwm_o      => open,            -- pwm channels

    -- Interrupts --

    mext_irq_i => '0'              -- machine external interrupt

  );

  -- TWI termination --

  twi_scl <= 'H';

  twi_sda <= 'H';

  -- Console UART Receiver ------------------------------------------------------------------

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

  uart_rx_console: process(clk_gen)

    variable i : integer;

    variable l : line;

  begin

    -- "UART" --

    if rising_edge(clk_gen) then

      -- synchronizer --

      uart_rx_sync <= uart_rx_sync(3 downto 0) & uart_txd;

      -- arbiter --

      if (uart_rx_busy = '0') then -- idle

        uart_rx_busy     <= '0';

        uart_rx_baud_cnt <= round(0.5 * baud_val_c);

        uart_rx_bitcnt   <= 9;

        if (uart_rx_sync(4 downto 1) = "1100") then -- start bit? (falling edge)

          uart_rx_busy <= '1';

        end if;

      else

        if (uart_rx_baud_cnt = 0.0) then

          if (uart_rx_bitcnt = 1) then

            uart_rx_baud_cnt <= round(0.5 * baud_val_c);

          else

            uart_rx_baud_cnt <= round(baud_val_c);

          end if;

          if (uart_rx_bitcnt = 0) then

            uart_rx_busy <= '0'; -- done

            i := to_integer(unsigned(uart_rx_sreg(8 downto 1)));

            if (i < 32) or (i > 32+95) then -- printable char?

              report "SIM_UART TX: (" & integer'image(i) & ")"; -- print code

            else

              report "SIM_UART TX: " & character'val(i); -- print ASCII

            end if;

            if (i = 10) then -- Linux line break

              writeline(file_uart_tx_out, l);

            elsif (i /= 13) then -- Remove additional carriage return

              write(l, character'val(i));

            end if;

          else

            uart_rx_sreg   <= uart_rx_sync(4) & uart_rx_sreg(8 downto 1);

            uart_rx_bitcnt <= uart_rx_bitcnt - 1;

          end if;

        else

          uart_rx_baud_cnt <= uart_rx_baud_cnt - 1.0;

        end if;

      end if;

    end if;

  end process uart_rx_console;

  -- Wishbone Memory ------------------------------------------------------------------------

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

  wb_mem_ram_access: process(clk_gen)

  begin

    if rising_edge(clk_gen) then

      -- control --

      wb_mem.rb_en(0) <= wb_cpu.cyc and wb_cpu.stb and wb_mem.acc_en and (not wb_cpu.we); -- read-back control

      wb_mem.ack(0)   <= wb_cpu.cyc and wb_cpu.stb and wb_mem.acc_en; -- wishbone acknowledge

      -- write access --

      if ((wb_cpu.cyc and wb_cpu.stb and wb_mem.acc_en and wb_cpu.we) = '1') then -- valid write access

        for i in 0 to 3 loop

          if (wb_cpu.sel(i) = '1') then

            wb_mem.ram(to_integer(unsigned(wb_cpu.addr(index_size_f(wb_mem_size_c/4)+1 downto 2))))(7+i*8 downto 0+i*8) <= wb_cpu.wdata(7+i*8 downto 0+i*8);

          end if;

        end loop; -- i

      end if;

      -- read access --

      wb_mem.rdata(0) <= wb_mem.ram(to_integer(unsigned(wb_cpu.addr(index_size_f(wb_mem_size_c/4)+1 downto 2)))); -- word aligned

      -- virtual read and ack latency --

      if (wb_mem_latency_c > 1) then

        for i in 1 to wb_mem_latency_c-1 loop

          wb_mem.rdata(i) <= wb_mem.rdata(i-1);

          wb_mem.rb_en(i) <= wb_mem.rb_en(i-1);

          wb_mem.ack(i)   <= wb_mem.ack(i-1);

        end loop;

      end if;

    end if;

  end process wb_mem_ram_access;

  -- wishbone memory access? --

  wb_mem.acc_en <= '1' when (wb_cpu.addr >= wb_mem_base_addr_c) and (wb_cpu.addr < std_ulogic_vector(unsigned(wb_mem_base_addr_c) + wb_mem_size_c)) else '0';

  -- output to cpu --

  wb_cpu.rdata <= wb_mem.rdata(wb_mem_latency_c-1) when (wb_mem.rb_en(wb_mem_latency_c-1) = '1') else (others=> '0'); -- data output gate

  wb_cpu.ack   <= wb_mem.ack(wb_mem_latency_c-1);

  wb_cpu.err   <= '0';

end neorv32_tb_rtl;