mt48lc4m32b2.v

mt48lc4m32b2.v 是128M sdram 中典型设计。。可以借鉴。

    end

    always @(negedge ras_in[1])
    begin:TRASfall1
        ras_out[1] <= #tdevice_TRASmax ras_in[1];
    end

    always @(posedge ras_in[2])
    begin:TRASrise2
        ras_out[2] <= #tdevice_TRASmin ras_in[2];
    end
    always @(negedge ras_in[2])
    begin:TRASfall2
        ras_out[2] <= #tdevice_TRASmax ras_in[2];
    end

    always @(posedge ras_in[3])
    begin:TRASrise3
        ras_out[3] <= #tdevice_TRASmin ras_in[3];
    end

    always @(negedge ras_in[3])
    begin:TRASfall3
        ras_out[3] <= #tdevice_TRASmax ras_in[3];
    end

    always @(posedge rcdt_in[0])
    begin:TRCDrise0
        rcdt_out[0] <= #5 1'b1;
    end
    always @(negedge rcdt_in[0])
    begin:TRCDfall0
        rcdt_out[0] <= #tdevice_TRCD 1'b0;
    end

    always @(posedge rcdt_in[1])
    begin:TRCDrise1
        rcdt_out[1] <= #5 1'b1;
    end
    always @(negedge rcdt_in[1])
    begin:TRCDfall1
        rcdt_out[1] <= #tdevice_TRCD 1'b0;
    end

    always @(posedge rcdt_in[2])
    begin:TRCDrise2
        rcdt_out[2] <= #5 1'b1;
    end
    always @(negedge rcdt_in[2])
    begin:TRCDfall2
        rcdt_out[2] <= #tdevice_TRCD 1'b0;
    end

    always @(posedge rcdt_in[3])
    begin:TRCDrise3
        rcdt_out[3] <= #5 1'b1;
    end
    always @(negedge rcdt_in[3])
    begin:TRCDfall3
        rcdt_out[3] <= #tdevice_TRCD 1'b0;
    end

    /////////////////////////////////////////////////////////////////////////
    // Functional Section
    /////////////////////////////////////////////////////////////////////////
    always @(posedge CLK)
    begin
        if ($time > Next_Ref && PoweredUp && Ref_Cnt > 0)
        begin
            Ref_Cnt = Ref_Cnt - 1;
            Next_Ref = $time + tdevice_REF;
        end
        if (CKEreg)
        begin
            if (~CSNeg_ipd)
                chip_en = 1;
            else
                chip_en = 0;
        end

        if (CKEreg && ~CSNeg_ipd)
        begin
            if (DQM0_ipd == 1'bx)
                $display(" Unusable value for DQM0 ");
            if (DQM1_ipd == 1'bx)
                $display(" Unusable value for DQM1 ");
            if (DQM2_ipd == 1'bx)
                $display(" Unusable value for DQM2 ");
            if (DQM3_ipd == 1'bx)
                $display(" Unusable value for DQM3 ");
            if (WENeg_ipd == 1'bx)
                $display(" Unusable value for WENeg ");
            if (RASNeg_ipd == 1'bx)
                $display(" Unusable value for RASNeg ");
            if (CASNeg_ipd == 1'bx)
                $display(" Unusable value for CASNeg ");

            // Command Decode
            if (RASNeg_ipd && CASNeg_ipd && WENeg_ipd)
                command = nop;
            else if (~RASNeg_ipd && CASNeg_ipd && WENeg_ipd)
                command = act;
            else if (RASNeg_ipd && ~CASNeg_ipd && WENeg_ipd)
                command = rd;
            else if (RASNeg_ipd && ~CASNeg_ipd && ~WENeg_ipd)
                command = writ;
            else if (RASNeg_ipd && CASNeg_ipd && ~WENeg_ipd)
                command = bst;
            else if (~RASNeg_ipd && CASNeg_ipd && ~WENeg_ipd)
                command = pre;
            else if (~RASNeg_ipd && ~CASNeg_ipd && WENeg_ipd)
                command = ref;
            else if (~RASNeg_ipd && ~CASNeg_ipd && ~WENeg_ipd)
                command = mrs;

            //  PowerUp Check
            if (~(PoweredUp) && command != nop)
            begin
                $display (" Incorrect power up. Command issued before ");
                $display (" power up complete. ");
            end

            //  Bank Decode
            if (~BA0_ipd && ~BA1_ipd)
                cur_bank = 0;
            else if (BA0_ipd && ~BA1_ipd)
                cur_bank = 1;
            else if (~BA0_ipd && BA1_ipd)
                cur_bank = 2;
            else if (BA0_ipd && BA1_ipd)
                cur_bank = 3;
            else
            begin
                $display ("Could not decode bank selection - results");
                $display ("may be incorrect.");
            end
        end

        // The Big State Machine
        if (CKEreg)
        begin
            if (CSNeg_ipd == 1'bx)
                $display ("Unusable value for CSNeg");

            if (CSNeg_ipd)
                command = nop;

            // DQM pipeline
            DQM0_reg2 = DQM0_reg1;
            DQM0_reg1 = DQM0_reg0;
            DQM0_reg0 = DQM0_ipd;
            DQM1_reg2 = DQM1_reg1;
            DQM1_reg1 = DQM1_reg0;
            DQM1_reg0 = DQM1_ipd;
            DQM2_reg2 = DQM2_reg1;
            DQM2_reg1 = DQM2_reg0;
            DQM2_reg0 = DQM2_ipd;
            DQM3_reg2 = DQM3_reg1;
            DQM3_reg1 = DQM3_reg0;
            DQM3_reg0 = DQM3_ipd;

            // by default data drive is Z, might get over written in one
            // of the passes below
            DataDrive = 32'bz;

            for (bank = 0; bank <= hi_bank; bank = bank + 1)
            begin
                case (statebank[bank])
                pwron :
                begin
                    if (~DQM0_ipd)
                    begin
                        $display ("DQM0 must be held high during");
                        $display ("initialization.");
                    end
                    if (~DQM1_ipd)
                    begin
                        $display ("DQM1 must be held high during");
                        $display ("initialization.");
                    end
                    if (~DQM2_ipd)
                    begin
                        $display ("DQM2 must be held high during");
                        $display ("initialization.");
                    end
                    if (~DQM3_ipd)
                    begin
                        $display ("DQM3 must be held high during");
                        $display ("initialization.");
                    end

                    if (~PoweredUp)
                    begin
                        if (command != nop)
                            $display ("Only NOPs allowed during power up.");
                        DataDrive = 32'bz;
                    end
                    else if (command == pre && (cur_bank == bank || A[10]))
                    begin
                        statebank[bank] = precharge;
                        statebank[bank] <= #tdevice_TRP idle;
                    end
                end

                precharge :
                begin
                    if (cur_bank == bank)
                    // It is only an error if this bank is selected
                        if (command != nop && command != pre)
                        begin
                            $display ("Illegal command received ");
                            $display ("during precharge.",$time);
                        end
                end

                idle :
                begin
                    if (command == nop || command == bst || command == pre
                        || cur_bank != bank)
                    begin
                    end
                    else if (command == mrs)
                    begin
                        if (statebank[0] == idle && statebank[1] == idle &&
                            statebank[2] == idle && statebank[3] == idle)
                        begin
                            ModeReg = A;
                            statebank[bank] = mode_set;
                        end
                    end
                    else if (command == ref)
                    begin
                        if (statebank[0] == idle && statebank[1] == idle &&
                            statebank[2] == idle && statebank[3] == idle)
                            if (CKE)
                            begin
                                statebank[bank] = auto_refresh;
                                statebank[bank] <= #tdevice_TRCAR idle;
                            end
                            else
                            begin
                                statebank[0] = self_refresh;
                                statebank[1] = self_refresh;
                                statebank[2] = self_refresh;
                                statebank[3] = self_refresh;
                            end
                    end
                    else if (command == act)
                    begin
                        statebank[bank] = bank_act;
                        ras_in[bank] = 1'b1;
                        ras_in [bank] <= #70 1'b0;
                        rct_in = 1'b1;
                        rct_in <= #1 1'b0;
                        rcdt_in[bank] = 1'b1;
                        rcdt_in[bank] <= #1 1'b0;
                        MemAddr[bank][19:8] = A; // latch row addr
                    end
                    else
               $display ("Illegal command received in idle state.",$time);
                end

                mode_set :
                begin
                    if (ModeReg[7] != 0 || ModeReg[8] != 0)
                        $display ("Illegal operating mode set.");
                    if (command != nop)
                    begin
                        $display ("Illegal command received during mode");
                        $display ("set.",$time);
                    end

                    // read burst length
                    if (ModeReg[2:0] == 3'b000)
                    begin
                        BurstLen = 1;
                        Burst_Bits = 0;
                    end
                    else if (ModeReg[2:0] == 3'b001)
                    begin
                        BurstLen = 2;
                        Burst_Bits = 1;
                    end
                    else if (ModeReg[2:0] == 3'b010)
                    begin
                        BurstLen = 4;
                        Burst_Bits = 2;
                    end
                    else if (ModeReg[2:0] == 3'b011)
                    begin
                        BurstLen = 8;
                        Burst_Bits = 3;
                    end
                    else if (ModeReg[2:0] == 3'b111)
                    begin
                        BurstLen = 256;
                        Burst_Bits = 7;
                    end
                    else
                        $display ("Invalid burst length specified.");

                    // read burst type
                    if (~ModeReg[3])
                        Burst = sequential;
                    else if (ModeReg[3])
                        Burst = interleave;
                    else
                        $display ("Invalid burst type specified.");

                    // read CAS latency
                    if (ModeReg[6:4] == 3'b001)
                    begin
                        CAS_Lat = 1'b1;
                        CAS_Lat2 = 1'b0;
                    end
                    else if (ModeReg[6:4] == 3'b010)
                    begin
                        CAS_Lat = 1'b0;
                        CAS_Lat2 = 1'b1;
                    end
                    else if (ModeReg[6:4] == 3'b011)
                    begin
                        CAS_Lat = 1'b1;
                        CAS_Lat2 = 1'b1;
                    end
                    else
                        $display ("CAS Latency set incorrecty");

                    // write burst mode
                    if (~ModeReg[9])
                        WB = programmed;
                    else if (ModeReg[9])
                        WB = single;
                    else
                        $display ("Invalid burst type specified.");

                    statebank[bank] = idle;
                end

                auto_refresh :
                begin
                    if (Ref_Cnt < 4096)
                        Ref_Cnt = Ref_Cnt + 1;
                    if (command != nop)
                    begin
                        $display ("Illegal command received during");
                        $display ("auto_refresh.",$time);
                    end
                end

                bank_act :
                begin
                    if (command == pre && (cur_bank == bank || A[10]))
                    begin
                        if (~ras_out[bank])