`timescale 1ns / 1ps

/********************************** I/O *********************************/

module main(   
    //Main clock.
    input clk,

     output [7:0]Led,    
     //Input buttons.
     input  [3:0]btn,
     //I2C controller.
     inout SCL,             //Clock line.
     inout SDA,             //Data line.
     //UART controller.
     input  rx,
     output tx

    PULLUP PULLUP_sda (.O(SDA));
    PULLUP PULLUP_scl (.O(SCL));
/**************************** Wires and Regs ****************************/

     wire ack0;             //IRQ ack set to interrupt flip flops.
     wire ack1;             //Not used in this design.
     wire ack2;             //Not used in this design.
     wire ack3;             //Not used in this design.
     wire sigout0;          //Interrupt 0 input from ff0.
     wire sigout1;          //Not used in this design.
     wire sigout2;          //Not used in this design.
     wire sigout3;          //Not used in this design.
     wire reset;            //Global reset.
     wire read;             //Read strobe.
     wire write;            //Write strobe.
     wire [15:0]id;         //ID for peripheral devices.
     wire [15:0]outdata;    //Data for peripheral devices.
     wire [35:0]inst;       //Instruction from program ROM.
     wire [15:0]in_port;    //Input from data MUX.
     wire [15:0]address;    //Address truncated by bus converter.
     //I2C controller.
     wire [15:0]i2cstatus;
     wire [7:0]i2cdata;
     //Button debouncer.
     wire [3:0]out_button;
     wire timer0out;
     wire [7:0]uartdata;
     wire [11:0]txcount;
     wire [11:0]rxcount;
/*************************** Hardware Modules ***************************/
     //If button 3 pressed, reset processor.
     assign reset = out_button[3];
     timer timer0(.clk(clk), .write(write), .id(id), .din(outdata), .reset(reset), .dout(timer0out));
     //Flip-flop for interrupt 0.
     FF ff0(.set(timer0out), .reset(ack0), .sigout(sigout0));
     //Flip-flop for interrupt 1(not used).
     FF ff1(.set(1'b0), .reset(ack1), .sigout(sigout1));
     //Flip-flop for interrupt 2(not used).
     FF ff2(.set(1'b0), .reset(ack2), .sigout(sigout2));
     //Flip-flop for interrupt 3(not used).
     FF ff3(.set(1'b0), .reset(ack3), .sigout(sigout3));
     //Processor input data MUX.
     dataMUX datamux(.read(read), .id(id), .i2cdata({8'h00, i2cdata}), .i2cstatus(i2cstatus), .dout(in_port),
                     .uartdata({8'h00, uartdata}), .txcount({4'h0, txcount}), .rxcount({4'h0, rxcount}),
                          .buttons({12'h000, out_button}));  
     //Program ROM for NMPSM3.
     prgROM ROM(.clka(clk), .addra(address[8:0]), .douta(inst));      
     //NMPSM3 soft processor.    
     NMPSM3 nmpsm3(.clk(clk), .reset(reset), .IRQ0(sigout0), .IRQ1(sigout1), .IRQ2(sigout2), .IRQ3(sigout3),
                   .INSTRUCTION(inst), .IN_PORT(in_port), .READ_STROBE(read), .WRITE_STROBE(write), .IRQ_ACK0(ack0),
                        .IRQ_ACK1(ack1), .IRQ_ACK2(ack2), .IRQ_ACK3(ack3), .ADDRESS(address), .OUT_PORT(outdata),
     ledio leds(.clk(clk), .reset(reset), .write(write), .id(id), .din(outdata), .ledsout(Led));
     //I2C controller.
     I2CTest1 i2c(.SCL(SCL), .SDA(SDA), .reset(reset), .write(write), .clk(clk), .id(id), .din(outdata),
     .i2cdata(i2cdata), .i2cstatus(i2cstatus));
     uart u(.clk(clk), .reset(reset), .id(id), .din(outdata), .write(write), .rx(rx),
           .tx(tx), .dout(uartdata), .txcount(txcount), .rxcount(rxcount));
     //Button debounce module.
     debounce dbc(.clk(clk), .in_button(btn), .out_button(out_button));