Subversion Repositories spacewire_light

--

-- Test bench for spwstream.

--

-- Tests:

--  * one spwstream instance with SpaceWire signals looped back to itself

--  * sending of bytes, packets and time codes through the SpaceWire link

--  * handling of link disabling and link disconnection

--

-- This test bench is intended to test the buffering logic in spwstream.

-- It does not thoroughly verify behaviour of the receiver, transmitter,

-- signal patterns etc. Please use spwlink_tb.vhd to test those aspects.

--

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

use std.textio.all;

use work.spwpkg.all;

entity streamtest_tb is

end entity;

architecture tb_arch of streamtest_tb is

    -- Parameters.

    constant sys_clock_freq: real   := 20.0e6;

    component streamtest is

        generic (

            sysfreq:    real;

            tickdiv:    integer range 12 to 24 := 20;

            rximpl:     spw_implementation_type := impl_generic;

            rxchunk:    integer range 1 to 4 := 1;

            tximpl:     spw_implementation_type := impl_generic;

            rxfifosize_bits: integer range 6 to 14 := 11;

            txfifosize_bits: integer range 2 to 14 := 11 );

        port (

            clk:        in  std_logic;

            rxclk:      in  std_logic;

            txclk:      in  std_logic;

            rst:        in  std_logic;

            linkstart:  in  std_logic;

            autostart:  in  std_logic;

            linkdisable: in std_logic;

            senddata:   in  std_logic;

            sendtick:   in  std_logic;

            txdivcnt:   in  std_logic_vector(7 downto 0);

            linkstarted: out std_logic;

            linkconnecting: out std_logic;

            linkrun:    out std_logic;

            linkerror:  out std_logic;

            gotdata:    out std_logic;

            dataerror:  out std_logic;

            tickerror:  out std_logic;

            spw_di:     in  std_logic;

            spw_si:     in  std_logic;

            spw_do:     out std_logic;

            spw_so:     out std_logic );

    end component;

    signal sys_clock_enable: std_logic := '0';

    signal sysclk:      std_logic := '0';

    signal s_loopback:  std_logic := '0';

    signal s_nreceived: integer := 0;

    signal s_rst:       std_logic := '1';

    signal s_linkstart: std_logic;

    signal s_autostart: std_logic;

    signal s_linkdisable: std_logic;

    signal s_divcnt:    std_logic_vector(7 downto 0);

    signal s_linkrun:   std_logic;

    signal s_linkerror: std_logic;

    signal s_gotdata:   std_logic;

    signal s_dataerror: std_logic;

    signal s_tickerror: std_logic;

    signal s_spwdi:     std_logic;

    signal s_spwsi:     std_logic;

    signal s_spwdo:     std_logic;

    signal s_spwso:     std_logic;

begin

    -- streamtest instance

    streamtest_inst: streamtest

        generic map (

            sysfreq     => sys_clock_freq,

            tickdiv     => 16,

            rximpl      => impl_generic,

            rxchunk     => 1,

            tximpl      => impl_generic,

            rxfifosize_bits => 9,

            txfifosize_bits => 8 )

        port map (

            clk         => sysclk,

            rxclk       => sysclk,

            txclk       => sysclk,

            rst         => s_rst,

            linkstart   => s_linkstart,

            autostart   => s_autostart,

            linkdisable => s_linkdisable,

            senddata    => '1',

            sendtick    => '1',

            txdivcnt    => s_divcnt,

            linkstarted => open,

            linkconnecting => open,

            linkrun     => s_linkrun,

            linkerror   => s_linkerror,

            gotdata     => s_gotdata,

            dataerror   => s_dataerror,

            tickerror   => s_tickerror,

            spw_di      => s_spwdi,

            spw_si      => s_spwsi,

            spw_do      => s_spwdo,

            spw_so      => s_spwso );

    -- Conditional loopback of SpaceWire signals.

    s_spwdi <= s_spwdo when (s_loopback = '1') else '0';

    s_spwsi <= s_spwso when (s_loopback = '1') else '0';

    -- Generate system clock.

    process is

    begin

        if sys_clock_enable /= '1' then

            wait until sys_clock_enable = '1';

        end if;

        sysclk  <= '1';

        wait for (0.5 sec) / sys_clock_freq;

        sysclk  <= '0';

        wait for (0.5 sec) / sys_clock_freq;

    end process;

    -- Verify that error indications remain off.

    process is

    begin

        wait on s_linkerror, s_dataerror, s_tickerror;

        assert s_dataerror = '0' report "Detected data error";

        assert s_tickerror = '0' report "Detected time code error";

        if s_loopback = '1' then

            assert s_linkerror /= '1' report "Unexpected link error";

        end if;

    end process;

    -- Verify that data is received regularly when the link is up.

    process is

    begin

        if s_linkrun = '0' or s_gotdata = '1' then

            wait until s_linkrun = '1' and s_gotdata = '0';

        end if;

        wait until s_gotdata = '1' or s_linkrun = '0' for 3 ms;

        if s_linkrun = '1' then

            assert s_gotdata = '1' report "Link running but no data received";

        end if;

    end process;

    -- Count number of received characters.

    process is

    begin

        wait until rising_edge(sysclk);

        if s_gotdata = '1' then

            s_nreceived <= s_nreceived + 1;

        end if;

    end process;

    -- Main process.

    process is

        variable vline: LINE;

    begin

        report "Starting streamtest test bench";

        -- Initialize.

        s_loopback  <= '1';

        s_rst       <= '1';

        s_linkstart <= '0';

        s_autostart <= '0';

        s_linkdisable <= '0';

        s_divcnt    <= "00000001";

        sys_clock_enable <= '1';

        wait for 1 us;

        -- Test link and data transmission.

        report "Testing txdivcnt = 1";

        s_rst       <= '0';

        s_linkstart <= '1';

        wait for 100 us;

        assert s_linkrun = '1' report "Link failed to start";

        wait for 50 ms;

        -- Check number of received characters.

        write(vline, string'("Received "));

        write(vline, s_nreceived);

        write(vline, string'(" characters in 50 ms."));

        writeline(output, vline);

        assert s_nreceived > 24000 report "Too few characters received";

        -- Test switching to different transmission rate.

        report "Testing txdivcnt = 2";

        s_divcnt    <= "00000010";

        wait for 10 ms;

        report "Testing txdivcnt = 3";

        s_divcnt    <= "00000011";

        wait for 10 ms;

        -- Disable and re-enable link.

        report "Testing link disable/re-enable";

        s_linkdisable <= '1';

        s_divcnt    <= "00000001";

        wait for 2 ms;

        s_linkdisable <= '0';

        wait for 100 us;

        assert s_linkrun = '1' report "Link failed to start after re-enable";

        wait for 10 ms;

        -- Cut and reconnect loopback wiring.

        report "Testing physical disconnect/reconnect";

        s_loopback  <= '0';

        wait for 2 ms;

        s_loopback  <= '1';

        wait for 100 us;

        assert s_linkrun = '1' report "Link failed to start after reconnect";

        wait for 10 ms;

        s_loopback  <= '0';

        wait for 2 ms;

        s_loopback  <= '1';

        wait for 100 us;

        assert s_linkrun = '1' report "Link failed to start after reconnect (2)";

        wait for 10 ms;

        -- Shut down.

        s_rst   <= '1';

        wait for 1 us;

        sys_clock_enable <= '0';

        write(vline, string'("Received "));

        write(vline, s_nreceived);

        write(vline, string'(" characters."));

        writeline(output, vline);

        report "Done";

        wait;

    end process;

end architecture tb_arch;