Subversion Repositories neorv32

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-- # << NEORV32 - Simple Testbench with UART-to-Console module >>                                  #

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-- # BSD 3-Clause License                                                                          #

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

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-- # 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_size_c      : natural := 256; -- wishbone memory size in bytes

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

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

  -- textio --

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

  -- internal configuration --

  constant baud_val_c : real    := f_clock_c / baud_rate_c;

  constant f_clk_c    : natural := natural(f_clock_c);

  -- reduced ASCII table --

  type ascii_t is array (0 to 94) of character;

  constant ascii_lut : ascii_t := (' ', '!', '"', '#', '$', '%', '&', ''', '(', ')', '*', '+', ',', '-',

  '.', '/', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ':', ';', '<', '=', '>', '?', '@', 'A',

  'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U',

  'V', 'W', 'X', 'Y', 'Z', '[', '\', ']', '^', '_', '`', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i',

  'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '{', '|', '}', '~');

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

  signal wb_mem_file : wb_mem_file_t := (others => (others => '0'));

  signal rb_en       : std_ulogic;

  signal r_data      : std_ulogic_vector(31 downto 0);

  signal wb_acc_en   : std_ulogic;

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

    HART_ID                   => x"ABCD1234",   -- custom hardware thread ID

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

    -- 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_Zicsr => true,          -- implement CSR system?

    -- Memory configuration: Instruction memory --

    MEM_ISPACE_BASE           => x"00000000",   -- base address of instruction memory space

    MEM_ISPACE_SIZE           => 16*1024,       -- total size of instruction memory space in byte

    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

    -- Memory configuration: Data memory --

    MEM_DSPACE_BASE           => x"80000000",   -- base address of data memory space

    MEM_DSPACE_SIZE           => 8*1024,        -- total size of data memory space in byte

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

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

    -- Memory configuration: 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_CLIC_USE               => true,          -- implement core local interrupt controller (CLIC)?

    IO_TRNG_USE               => false          -- implement true random number generator (TRNG)?

  )

  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

    -- 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_sclk_o => open,            -- serial clock line

    spi_mosi_o => spi_data,        -- serial data line out

    spi_miso_i => spi_data,        -- serial data line in

    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 --

    ext_irq_i  => (others => '0'), -- external interrupt request

    ext_ack_o  => open             -- external interrupt request acknowledge

  );

  -- twi termination --

  twi_scl <= 'H';

  twi_sda <= 'H';

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

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

  uart_rx_console: process(clk_gen)

    variable i, j     : integer;

    variable line_tmp : 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

          -- adapt to the inter-frame pause - which is not implemented in the neo430 uart ;)

          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)));

            j := i - 32;

            if (j < 0) or (j > 95) then

              j := 0; -- undefined = SPACE

            end if;

            if (i < 32) or (j > 32+95) then

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

            else

              report "UART TX: " & ascii_lut(j); -- print ASCII

            end if;

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

              writeline(file_uart_tx_out, line_tmp);

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

              write(line_tmp, ascii_lut(j));

            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_file_access: process(clk_gen)

    begin

      if rising_edge(clk_gen) then

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

        wb_cpu.ack <= wb_cpu.cyc and wb_cpu.stb and wb_acc_en; -- wishbone acknowledge

        if ((wb_cpu.cyc and wb_cpu.stb and wb_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_file(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;

        r_data <= wb_mem_file(to_integer(unsigned(wb_cpu.addr(index_size_f(wb_mem_size_c/4)+1 downto 2)))); -- word aligned

      end if;

    end process wb_mem_file_access;

  -- wb mem access --

  wb_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 gate --

  wb_cpu.rdata <= r_data when (rb_en = '1') else (others=> '0');

  wb_cpu.err <= '0';

end neorv32_tb_rtl;