`timescale 1ns / 1ps// Lab design for the Designing for Performance ChipScope lab.
// This design is based on a reference design for the Spartan-3E Starter Kit.
//
// Constantly scroll the text ?SPARTAN-3E STARTER KIT" and "www.xilinx.com/s3estarter? across the LCD.
//
// SW0 turns on LD0
// SW1 turns on LD1                                                  Single LED is moved left or
// SW2 turns on LD2                                                  right by rotation of control.
// SW3 turns on LD3                           OR
// BTN East turns on LD4               by pressing centre
// BTN South turns on LD5            button of rotary encoder
// BTN North turns on LD6                toggle mode
// BTN West turns on LD7
//
// PicoBlaze provides full control over the LCD display.
//////////////////////////////////////////////////////////////////////////////////
module s3esk_startup(led, strataflash_oe, strataflash_ce, strataflash_we, switch, btn_north, btn_east, btn_south, btn_west, lcd_d, lcd_rs, lcd_rw, lcd_e, rotary_a, rotary_b, rotary_press, clk);    output reg [7:0] led;    output strataflash_oe;    output strataflash_ce;    output strataflash_we;    input [3:0] switch;    input btn_north;    input btn_east;    input btn_south;    input btn_west;    inout [7:4] lcd_d;    output reg lcd_rs;    output lcd_rw;    output reg lcd_e;    input rotary_a;    input rotary_b;    input rotary_press;    input clk;//////////////////////////////////////////////////////////////////////////////////// Signals used by ChipScope Pro cores
//

//
// Signals used to connect KCPSM3 to program ROM and I/O logic
//
wire [9:0]  address;
wire [17:0] instruction;
wire [7:0]  port_id;
wire [7:0]  out_port;
reg  [7:0]  in_port;
wire        write_strobe;
wire        read_strobe;
reg         interrupt;
wire        interrupt_ack;
wire        kcpsm3_reset;
//
// Signals used to connect program ROM to BSCAN
//
// The BSCAN component would normally be embedded in the control block,
// but it is instantiated at the top level to facilitate replacing it
// with the BSCAN component that will be included in the ICON core.
//
wire capture;
wire drck1;
wire drck2;
wire reset;
wire sel1;
wire sel2;
wire shift;
wire tdi;
wire update;
wire tdo1;
wire tdo2;
//
//
// Signals for LCD operation
//
// Tri-state output requires internal signals
// 'lcd_drive' is used to differentiate between LCD and StrataFLASH communications 
// which share the same data bits.
//
reg       lcd_rw_control;
reg [7:4] lcd_output_data;
reg       lcd_drive;
//
//
// Signals used to interface to rotary encoder
//
reg       rotary_a_in;
reg       rotary_b_in;
reg       rotary_press_in;
reg [1:0] rotary_in;
reg       rotary_q1;
reg       rotary_q2;
reg       delay_rotary_q1;
reg       rotary_event;
reg       rotary_left;
//////////////////////////////////////////////////////////////////////////////////// Start of circuit description
//
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  // Instantiate ChipScope Pro cores here
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  //
  
  //
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  // Disable unused components  
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  //
  //StrataFLASH must be disabled to prevent it conflicting with the LCD display 
  //
  assign strataflash_oe = 1'b1;
  assign strataflash_ce = 1'b1;
  assign strataflash_we = 1'b1;
  //
  //
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  // KCPSM3 and the program memory 
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  //

  kcpsm3 processor (
    .address(address),
    .instruction(instruction),
    .port_id(port_id),
    .write_strobe(write_strobe),
    .out_port(out_port),
    .read_strobe(read_strobe),
    .in_port(in_port),
    .interrupt(interrupt),
    .interrupt_ack(interrupt_ack),
    .reset(kcpsm3_reset),
    .clk(clk)
	 );
 
  control program_rom (
    .address(address),
    .instruction(instruction),
    .proc_reset(kcpsm3_reset),                       //JTAG Loader version 
    .clk(clk),
    .tdi(tdi),
    .update(update),
    .sel1(sel1),
    .drck1(drck1),
	 .tdo1(tdo1)
	 );

   BSCAN_SPARTAN3 BSCAN_SPARTAN3_inst (      .CAPTURE(capture), // CAPTURE output from TAP controller      .DRCK1(drck1),     // Data register output for USER1 functions      .DRCK2(drck2),     // Data register output for USER2 functions      .RESET(reset),     // Reset output from TAP controller      .SEL1(sel1),       // USER1 active output      .SEL2(sel2),       // USER2 active output      .SHIFT(shift),     // SHIFT output from TAP controller      .TDI(tdi),         // TDI output from TAP controller      .UPDATE(update),   // UPDATE output from TAP controller      .TDO1(tdo1),       // Data input for USER1 function      .TDO2(tdo2)        // Data input for USER2 function   );  
  //
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  // Interrupt 
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  //
  // Interrupt is used to detect rotation of the rotary encoder.
  // It is anticipated that the processor will respond to interrupts at a far higher 
  // rate that the rotary control can be operated and hence events will not be missed. 
  //

  always @(posedge clk)      if (interrupt_ack) begin         interrupt <= 0;      end      else if (rotary_event) begin         interrupt <= 1;      end
		else begin 
		   interrupt <= interrupt;
		end				
  //
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  // KCPSM3 input ports 
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  //
  //
  // The inputs connect via a pipelined multiplexer
  //

  always @(posedge clk)      case (port_id[1:0])
		        // read simple toggle switches and buttons at address 00 hex         2'b00: in_port = {btn_west, btn_north, btn_south, btn_east, switch};        
		  // read rotary control signals at address 01 hex         2'b01: in_port = {6'b000000, rotary_press_in, rotary_left};        
		  // read LCD data at address 02 hex         2'b10: in_port = {lcd_d, 4'b0000};
			        // Address 03 hex is unused         2'b11: in_port = 8'b00000000;      endcase
		
  //
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  // KCPSM3 output ports 
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  //

  // adding the output registers to the processor

  always @(posedge clk)
      if (write_strobe) begin
		
		  // Write to LEDs at address 80 hex.
		  if (port_id[7]) begin
		     led <= out_port;
		  end
		  
		  // LCD data output and controls at address 40 hex.
		  if (port_id[6]) begin
		     lcd_output_data <= out_port[7:4];
			  lcd_drive <= out_port[3];
			  lcd_rs <= out_port[2];
			  lcd_rw_control <= out_port[1];
			  lcd_e <= out_port[0];
		  end		  
      end

  //
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  // LCD interface  
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  //
  // The 4-bit data port is bidirectional.
  // lcd_rw is '1' for read and '0' for write 
  // lcd_drive is like a master enable signal which prevents either the 
  // FPGA outputs or the LCD display driving the data lines.
  //
  // Control of read and write signal
  assign lcd_rw = lcd_rw_control & lcd_drive;

  // use read/write control to enable output buffers.
  assign lcd_d = (!lcd_rw_control && lcd_drive) ? lcd_output_data : 4'bZZZZ;

  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  // Interface to rotary encoder.
  // Detection of movement and direction.
  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////  //
  // The rotary switch contacts are filtered using their offset (one-hot) style to  
  // clean them. Circuit concept by Peter Alfke.
  // Note that the clock rate is fast compared with the switch rate.

  always @(posedge clk) begin
      
		// Synchronise inputs to clock domain using flip-flops in input/output blocks.
		rotary_a_in <= rotary_a;      rotary_b_in <= rotary_b;      rotary_press_in <= rotary_press;
		
		// Concatinate rotary input signals to form vector for case construct.
		rotary_in <= {rotary_b_in, rotary_a_in};
		
		case (rotary_in)		         2'b00: begin
			       rotary_q1 <= 1'b0;
					 rotary_q2 <= rotary_q2;
			end                 2'b01: begin
			       rotary_q1 <= rotary_q1;
					 rotary_q2 <= 1'b0;
			end                 2'b10: begin
			       rotary_q1 <= rotary_q1;
					 rotary_q2 <= 1'b1;
			end			         2'b11: begin
			       rotary_q1 <= 1'b1;
					 rotary_q2 <= rotary_q2;
			end      endcase
	end

  //
  // The rising edges of 'rotary_q1' indicate that a rotation has occurred and the 
  // state of 'rotary_q2' at that time will indicate the direction. 
  //
  
  always @(posedge clk) begin
      delay_rotary_q1 <= rotary_q1;
		if (rotary_q1 && !delay_rotary_q1) begin
		   rotary_event <= 1'b1;
			rotary_left <= 1'b1;
      end
		else begin
		   rotary_event <= 1'b0;
			rotary_left <= rotary_left;
		end
	end
endmodule