em_sdram.pm

SDRAM Controller For Altera SOPC Builder and NIOS on DE2 kit board

    










    











    
    my $refresh_counter_reload_value = $WSA->{refresh_period} - 1;

    



    my $init_countdown_value = $WSA->{powerup_delay} + $WSA->{init_nop_delay};



    my $refresh_counter_width =
     Bits_To_Encode(max($refresh_counter_reload_value, $init_countdown_value));
    
    $module->add_contents
        (
         e_signal->new({
             name => "refresh_counter",
             width => $refresh_counter_width,
         }),
         e_process->new
         ({
             comment => " Refresh/init counter.",
             contents => 
                 [
                  e_if->new({
                      condition => "(refresh_counter == 0)",
                      then => [e_assign->new({
                          lhs => "refresh_counter",
                          rhs => $refresh_counter_reload_value,
                      })],
                      else => [e_assign->new({
                          lhs => "refresh_counter",
                          rhs => "refresh_counter - 1'b1",
                      })],
                  }),
                  ],
             asynchronous_contents => 
                 [
                  e_assign->new({
                      lhs => "refresh_counter",
                      rhs => $init_countdown_value
                      }),
                  ],
          }),
         );
    

    $module->add_contents
        (
         e_register->new({
             comment   => " Refresh request signal.",
             in        => "((refresh_counter == 0) | refresh_request)".
                 " & ~ack_refresh_request & init_done",
             out       => e_signal->new({name => "refresh_request"}),
             enable    => undef,
         })
         );


    $module->add_contents
        (
         e_register->new({
             comment   =>
 " Generate an Interrupt if two ref_reqs occur before one ack_refresh_request",
             in        => "(refresh_counter == 0) & refresh_request",

             out       => e_signal->new({name => "za_cannotrefresh",
                                         never_export => 1}),
             enable    => undef,
             })
         );


    my @signals = ("i_cmd", "m_cmd");
    foreach my $signal (@signals)
    {
        $module->add_contents
            (e_signal->new({name => "$signal",
                            width => 3 + $num_chipselects }));
    }
    @signals = ("i_addr", "m_addr");
    foreach my $signal (@signals)
    {
        $module->add_contents
            (e_signal->new({name => "$signal",
                            width => $WSA->{sdram_addr_width}}));
    }
    








    my ( $I_RESET, $I_PRECH, $I_WAIT,  $I_ARF,   $I_LMR,   $I_INIT) =
        ("3'b000", "3'b001", "3'b011", "3'b010", "3'b111", "3'b101");








    $module->add_contents(
                          e_signal->new({
                              name => "init_done",
                          }),
                          e_register->new({
                              comment => " Initialization-done flag.",
                              in => "init_done | (i_state == $I_INIT)",
                              out => "init_done",
                              enable => undef,
                          })
                          );


    my ($LMR,$REFRESH,$PRECHARGE,$ACTIVE,$WRITE,$READ,$BURST,$NOP,$INHIBIT) =
       ("3'h0","3'h1","3'h2",   "3'h3", "3'h4","3'h5","3'h6","3'h7","3'h7");



    my $ALL = "{".$num_chipselects."{1'b0}}";
    my $NONE= "{".$num_chipselects."{1'b1}}";
    



    my $none_and_inhibit = replicate_bit(3 + $num_chipselects, 1);








    my $MRD = "{{".($WSA->{sdram_addr_width} - 10).
        "{1'b0}},1'b0,2'b00,3'h".$WSA->{cas_latency}.",4'h0}";

    @signals = ("i_state", "i_next");
    foreach my $signal (@signals)
    {
        $module->add_contents
            (e_signal->new({name => "$signal", width => 3}));
    }
    
    my $initfsm_counter_width =
        Bits_To_Encode(max($trp, $trfc, $tmrd, $trcd, $twr));
    

    $module->add_contents
        (e_signal->news
         (
          {name => "i_count", width => $initfsm_counter_width},
          {name => "i_refs",  width => 3},
          )
         );


    


    my %i_contents_hash =
        (
         $I_RESET => [
                      e_assign->news
                      (
                       ["i_cmd"  => $none_and_inhibit],
                       ["i_refs" => "3'b0"],
                       ),
                      e_if->new
                      ({
                          comment => "Wait for refresh count-down after reset",
                          condition => "refresh_counter == 0",
                          then => ["i_state" => $I_PRECH],
                      }),
                      ],
         $I_PRECH => [
                      e_assign->news
                      (
                       ["i_state"=>$I_WAIT],
                       ["i_cmd"  =>"{".$ALL.",".$PRECHARGE."}"],
                       ["i_count"=>$trp],
                       ["i_next" =>$I_ARF],
                       ),
                      ],
         $I_ARF   => [
                      e_assign->news
                      (
                       ["i_cmd"  => "{".$ALL.",".$REFRESH."}"],
                       ["i_refs" => "i_refs + 1'b1"],
                       ["i_state"=> $I_WAIT],
                       ["i_count"=> $trfc],
                       ),
                      e_if->new
                      ({
                          comment => " Count up init_refresh_commands",
                          condition => "i_refs == 3'h".
                              ($WSA->{init_refresh_commands} - 1),
                          then => ["i_next" => $I_LMR],
                          else => ["i_next" => $I_ARF],
                      }),
                      ],
         $I_LMR   => [
                      e_assign->news
                      (
                       ["i_state"  => $I_WAIT],
                       ["i_cmd"    => "{".$ALL.",".$LMR."}"],
                       ["i_addr"   => $MRD],
                       ["i_count"  => $tmrd],
                       ["i_next"   => $I_INIT],
                       ),
                      ],

         $I_INIT  => [i_state => $I_INIT],
         default  => [i_state => $I_RESET],
         );


    my $i_next_waitlist = [];
    
    if ($tristate_bridge_mode == 0)
    {
        $i_next_waitlist = 
            [
             e_assign->new(["i_cmd" => "{".$ALL.",".$NOP."}"]),
             e_if->new
             ({
                 comment => "WAIT til safe to Proceed...",
                 condition => "i_count > 1",
                 then => ["i_count", "i_count - 1'b1"],
                 else => ["i_state", "i_next"],
             }),
             ],
    }
    else
    {
        $i_next_waitlist =
            [
             e_if->new
             ({
                 comment => " wait for tz_waitrequest",
                 condition => "!tz_waitrequest",
                 then =>
                     [
                      e_assign->new(["i_cmd" => "{".$ALL.",".$NOP."}"]),
                      e_if->new
                      ({
                          comment => "WAIT til safe to Proceed...",
                          condition => "i_count > 1",
                          then => ["i_count", "i_count - 1'b1"],
                          else => ["i_state", "i_next"],
                      }),
                      ],
             }),
             ];
    }
    
    $i_contents_hash{$I_WAIT} = $i_next_waitlist;



    $module->add_contents
        (
         e_process->new
         ({
             comment => " **** Init FSM ****",
             asynchronous_contents => 
                 [
                  e_assign->news
                  (
                   ["i_state"  => $I_RESET],
                   ["i_next"   => $I_RESET],
                   ["i_cmd"    => $none_and_inhibit],
                   ["i_addr"   => "{".$WSA->{sdram_addr_width}."{1'b1}}"],
                   ["i_count"  => "{".$initfsm_counter_width."{1'b0}}"],
                   ),
                  ], # end async_contents
             contents =>
                 [
                  e_assign->news
                  (
                   ["i_addr"    => "{".$WSA->{sdram_addr_width}."{1'b1}}"],
                   ),
                  e_case->new
                  ({
                      switch => "i_state",
                      parallel => 1,
                      full => 1,
                      contents => {%i_contents_hash},
                  }),
                  ],            # end contents
         }),                    # end process
         );                     # end add_contents















    my $num_main_fsm_states;
    my ($M_IDLE, $M_RAS, $M_WAIT,$M_RD, $M_WR, $M_REC, $M_PRE, $M_REF,$M_OPEN);

    if ($tristate_bridge_mode == 1)
    {
        $num_main_fsm_states = 8;
        ($M_IDLE, $M_RAS, $M_WAIT, $M_RD, $M_WR, $M_REC, $M_PRE, $M_REF) =
            &one_hot_encoding($num_main_fsm_states);
    }
    else
    {
        $num_main_fsm_states = 9;
        ($M_IDLE,$M_RAS,$M_WAIT,$M_RD,$M_WR,$M_REC,$M_PRE,$M_REF,$M_OPEN)=
            &one_hot_encoding($num_main_fsm_states);
    }

    @signals = ("m_state", "m_next");
    foreach my $signal (@signals)
    {
        $module->add_contents
            (e_signal->new({name => "$signal",
                       width => Bits_To_Encode((2**$num_main_fsm_states)-1)}));
    }

    $module->add_contents       # uses same values as initfsm_counter_width
        (e_signal->new({name => "m_count", width => $initfsm_counter_width}));
    






    




    if ($WSA->{sdram_bank_width} == 1)
    {
        $module->add_contents
            (
             e_assign->new
             (["active_bank"=> "active_addr[$bottom_bank_addr]"]),
             );
    }
    else
    {
        $module->add_contents
            (
             e_assign->new
             (["active_bank"=> 
               "{active_addr[$top_bank_addr],active_addr[$bottom_bank_addr]}"]),
             );
    }

    $module->add_contents
        (
         e_assign->news
         (
          ["csn_match"  => "active_cs_n == f_cs_n"],
          ["rnw_match"  => "active_rnw == f_rnw"],
          ["bank_match" => "active_bank == f_bank"],
          ["row_match"  =>
           "{active_addr[$top_row_addr:$bottom_row_addr]} == ".
           "{f_addr[$top_row_addr:$bottom_row_addr]}"],
          ),
         e_assign->new
         (
          ["pending" =>
           "csn_match && rnw_match && bank_match && row_match && !f_empty"],
          ),
         );


    my $cas_pad = $WSA->{sdram_addr_width} - ($WSA->{sdram_col_width} + 1);
    my $cas_pad_expression;