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`timescale 1ns / 1ps

/*

 * File         : Top.v

 * Project      : University of Utah, XUM Project MIPS32 core

 * Creator(s)   : Grant Ayers (ayers@cs.utah.edu)

 *

 * Modification History:

 *   Rev   Date         Initials  Description of Change

 *   1.0   8-Jul-2011   GEA       Initial design.

 *

 * Standards/Formatting:

 *   Verilog 2001, 4 soft tab, wide column.

 *

 * Description:

 *   The top-level file for the FPGA. Also known as the 'motherboard,' this

 *   file connects all processor, memory, clocks, and I/O devices together.

 *   All inputs and outputs correspond to actual FPGA pins.

 */

module Top(

    input  clock_100MHz,

    input  reset_n,

    // I/O

    input  [7:0] Switch,

    output [14:0] LED,

    output [6:0] LCD,

    input  UART_Rx,

    output UART_Tx,

    inout  i2c_scl,

    inout  i2c_sda,

    output Piezo

    );

    // Clock signals

    wire clock, clock2x;

    wire PLL_Locked;

    reg reset;

    always @(posedge clock) begin

        reset <= ~reset_n | ~PLL_Locked;

    end

    // MIPS Processor Signals

    reg  [31:0] MIPS32_DataMem_In;

    wire [31:0] MIPS32_DataMem_Out, MIPS32_InstMem_In;

    wire [29:0] MIPS32_DataMem_Address, MIPS32_InstMem_Address;

    wire [3:0]  MIPS32_DataMem_WE;

    wire        MIPS32_DataMem_Read, MIPS32_InstMem_Read;

    reg         MIPS32_DataMem_Ready;

    wire [4:0]  MIPS32_Interrupts;

    wire        MIPS32_NMI;

    wire [7:0]  MIPS32_IP;

    wire        MIPS32_IO_WE;

    // BRAM Memory Signals

    reg  [3:0] BRAM_WEA;

    reg  BRAM_REA;

    reg  [17:0] BRAM_AddrA;

    reg  [31:0] BRAM_DINA;

    wire BRAM_ReadyA;

    wire BRAM_REB;

    wire [3:0] BRAM_WEB;

    wire [31:0] BRAM_DOUTB;

    wire BRAM_ReadyB;

    // LCD Signals

    wire [3:0] LCD_WE;

    wire LCD_Ready;

    // UART Bootloader Signals

    wire UART_RE;

    wire UART_WE;

    wire [16:0] UART_DOUT;

    wire UART_Ack;

    wire UART_Interrupt;

    wire UART_BootResetCPU;

    wire [17:0] UART_BootAddress;

    wire [31:0] UART_BootData;

    wire UART_BootWriteMem_pre;

    wire [3:0] UART_BootWriteMem = (UART_BootWriteMem_pre) ? 4'hF : 4'h0;

    // I2C Signals

    wire I2C_Ready;

    wire [10:0] I2C_DOUT;

    wire I2C_RE, I2C_WE;

    // Piezo Transducer Signals

    wire Piezo_WE;

    wire Piezo_Ready;

    // LED Signals

    wire LED_WE;

    wire LED_RE;

    wire [13:0] LED_DOUT;

    wire LED_Ready;

    wire [13:0] LED_Sw_LEDs;

    // Filtered Switch Input Signals

    wire Switches_RE;

    wire Switches_WE;

    wire Switches_Ready;

    wire [7:0] Switches_DOUT;

    // Clock Generation

    PLL_100MHz_to_33MHz_66MHz Clock_Generator (

        .CLKIN1_IN    (clock_100MHz),

        .RST_IN       (1'b0),

        .CLKOUT0_OUT  (clock),

        .CLKOUT1_OUT  (clock2x),

        .LOCKED_OUT   (PLL_Locked)

    );

    // MIPS-32 Core

    Processor MIPS32 (

        .clock            (clock),

        .reset            ((reset | UART_BootResetCPU)),

        .Interrupts       (MIPS32_Interrupts),

        .NMI              (MIPS32_NMI),

        .DataMem_In       (MIPS32_DataMem_In),

        .DataMem_Ready    (MIPS32_DataMem_Ready),

        .DataMem_Read     (MIPS32_DataMem_Read),

        .DataMem_Write    (MIPS32_DataMem_WE),

        .DataMem_Address  (MIPS32_DataMem_Address),

        .DataMem_Out      (MIPS32_DataMem_Out),

        .InstMem_In       (MIPS32_InstMem_In),

        .InstMem_Address  (MIPS32_InstMem_Address),

        .InstMem_Ready    (BRAM_ReadyA),

        .InstMem_Read     (MIPS32_InstMem_Read),

        .IP               (MIPS32_IP)

    );

    // On-Chip Block RAM

    BRAM_592KB_Wrapper Memory (

        .clock    (clock2x),

        .reset    (reset),

        .rea      (BRAM_REA),

        .wea      (BRAM_WEA),

        .addra    (BRAM_AddrA),

        .dina     (BRAM_DINA),

        .douta    (MIPS32_InstMem_In),

        .dreadya  (BRAM_ReadyA),

        .reb      (BRAM_REB),

        .web      (BRAM_WEB),

        .addrb    (MIPS32_DataMem_Address[17:0]),

        .dinb     (MIPS32_DataMem_Out),

        .doutb    (BRAM_DOUTB),

        .dreadyb  (BRAM_ReadyB)

    );

    // 16x2 LCD Display Screen

    LCD LCD_Screen (

        .clock_100MHz  (clock2x),

        .clock_Mem     (clock2x),

        .reset         (reset),

        .address       (MIPS32_DataMem_Address[2:0]),

        .data          (MIPS32_DataMem_Out),

        .writeEnable   (LCD_WE),

        .ack           (LCD_Ready),

        .LCD           (LCD)

    );

    // UART + Boot Loader (v2)

    uart_bootloader UART (

        .clock         (clock2x),

        .reset         (reset),

        .Read          (UART_RE),

        .Write         (UART_WE),

        .DataIn        (MIPS32_DataMem_Out[8:0]),

        .DataOut       (UART_DOUT),

        .Ack           (UART_Ack),

        .DataReady     (UART_Interrupt),

        .BootResetCPU  (UART_BootResetCPU),

        .BootWriteMem  (UART_BootWriteMem_pre),

        .BootAddr      (UART_BootAddress),

        .BootData      (UART_BootData),

        .RxD           (UART_Rx),

        .TxD           (UART_Tx)

    );

    // I2C Module

    I2C_Controller I2C (

        .clock    (clock2x),

        .reset    (reset),

        .Read     (I2C_RE),

        .Write    (I2C_WE),

        .DataIn   (MIPS32_DataMem_Out[12:0]),

        .DataOut  (I2C_DOUT),

        .Ack      (I2C_Ready),

        .i2c_scl  (i2c_scl),

        .i2c_sda  (i2c_sda)

    );

    // Piezo-electric Transducer

    Piezo_Driver Piezo_Driver (

        .clock  (clock2x),

        .reset  (reset),

        .data   (MIPS32_DataMem_Out[24:0]),

        .Write  (Piezo_WE),

        .Ack    (Piezo_Ready),

        .Piezo  (Piezo)

    );

    // LEDs

    LED LEDs (

        .clock    (clock2x),

        .reset    (reset),

        .dataIn   (MIPS32_DataMem_Out[14:0]),

        .IP       (MIPS32_IP),

        .Write    (LED_WE),

        .Read     (LED_RE),

        .dataOut  (LED_DOUT),

        .Ack      (LED_Ready),

        .LED      (LED_Sw_LEDs)

    );

    // Filtered Input Switches

    Switches Switches (

        .clock       (clock2x),

        .reset       (reset),

        .Read        (Switches_RE),

        .Write       (Switches_WE),

        .Switch_in   (Switch),

        .Ack         (Switches_Ready),

        .Switch_out  (Switches_DOUT)

    );

    assign MIPS32_IO_WE = (MIPS32_DataMem_WE == 4'hF) ? 1 : 0;

    assign MIPS32_Interrupts[4:1] = Switches_DOUT[7:4];

    assign MIPS32_Interrupts[0]   = UART_Interrupt;

    assign MIPS32_NMI             = Switches_DOUT[3];

    assign LED = {UART_BootResetCPU, LED_Sw_LEDs[13:0]};

    // Allow writes to Instruction Memory Port when bootloading

    always @(*) begin

        BRAM_REA   <= (UART_BootResetCPU) ? 0 : MIPS32_InstMem_Read;

        BRAM_WEA   <= (UART_BootResetCPU) ? UART_BootWriteMem : 4'h0;

        BRAM_AddrA <= (UART_BootResetCPU) ? UART_BootAddress : MIPS32_InstMem_Address;

        BRAM_DINA  <= (UART_BootResetCPU) ? UART_BootData : 32'h0000_0000;

    end

    always @(*) begin

        case (MIPS32_DataMem_Address[29])

                    MIPS32_DataMem_In    <= BRAM_DOUTB;

                    MIPS32_DataMem_Ready <= BRAM_ReadyB;

                end

            1 : begin

                    // Memory-mapped I/O

                    case (MIPS32_DataMem_Address[28:26])

                        // LCD

                        3'b000 :    begin

                                        MIPS32_DataMem_In    <= 32'h0000_0000;

                                        MIPS32_DataMem_Ready <= LCD_Ready;

                                    end

                        // I2C

                        3'b001 :    begin

                                        MIPS32_DataMem_In    <= {21'h000000, I2C_DOUT[10:0]};

                                        MIPS32_DataMem_Ready <= I2C_Ready;

                                    end

                        // Piezo

                        3'b010 :    begin

                                        MIPS32_DataMem_In    <= 32'h0000_0000;

                                        MIPS32_DataMem_Ready <= Piezo_Ready;

                                    end

                        // UART

                        3'b011 :    begin

                                        MIPS32_DataMem_In    <= {15'h0000, UART_DOUT[16:0]};

                                        MIPS32_DataMem_Ready <= UART_Ack;

                                    end

                        // LED

                        3'b100 :    begin

                                        MIPS32_DataMem_In    <= {18'h00000, LED_DOUT[13:0]};

                                        MIPS32_DataMem_Ready <= LED_Ready;

                                    end

                        // Switches

                        3'b101 :    begin

                                        MIPS32_DataMem_In    <= {24'h000000, Switches_DOUT[7:0]};

                                        MIPS32_DataMem_Ready <= Switches_Ready;

                                    end

                        default:    begin

                                        MIPS32_DataMem_In    <= 32'h0000_0000;

                                        MIPS32_DataMem_Ready <= 0;

                                    end

                    endcase

                end

        endcase

    end

    // Memory

    assign BRAM_REB    = (MIPS32_DataMem_Address[29]) ? 0    : MIPS32_DataMem_Read;

    assign BRAM_WEB    = (MIPS32_DataMem_Address[29]) ? 4'h0 : MIPS32_DataMem_WE;

    // I/O

    assign LCD_WE      = (MIPS32_DataMem_Address[29:26] == 4'b1000) ? MIPS32_DataMem_WE : 4'h0;

    assign Piezo_WE    = (MIPS32_DataMem_Address[29:26] == 4'b1010) ? MIPS32_IO_WE : 0;

    assign I2C_WE      = (MIPS32_DataMem_Address[29:26] == 4'b1001) ? MIPS32_IO_WE : 0;

    assign I2C_RE      = (MIPS32_DataMem_Address[29:26] == 4'b1001) ? MIPS32_DataMem_Read : 0;

    assign UART_WE     = (MIPS32_DataMem_Address[29:26] == 4'b1011) ? MIPS32_IO_WE : 0;

    assign UART_RE     = (MIPS32_DataMem_Address[29:26] == 4'b1011) ? MIPS32_DataMem_Read : 0;

    assign LED_WE      = (MIPS32_DataMem_Address[29:26] == 4'b1100) ? MIPS32_IO_WE : 0;

    assign LED_RE      = (MIPS32_DataMem_Address[29:26] == 4'b1100) ? MIPS32_DataMem_Read : 0;

    assign Switches_WE = (MIPS32_DataMem_Address[29:26] == 4'b1101) ? MIPS32_IO_WE : 0;

    assign Switches_RE = (MIPS32_DataMem_Address[29:26] == 4'b1101) ? MIPS32_DataMem_Read : 0;

endmodule