flash.v

   1 `include "processor_4.v"
   2
   3 module top (input CLK, output [7:0] OUT_C, output [2:0] OUT_R, output [3:0] IN_C, input [3:0] IN_R, output [3:0] IND, output UART_TX, input UART_RX);
   4
   5     wire [23:0] led;
   6
   7     // Prescaler on the clock
   8
   9     reg [24:0] counter = 0;
  10
  11     always @ (posedge CLK) begin
  12
  13         counter <= counter + 1;
  14
  15     end
  16
  17     // Handle the inputs
  18
  19     reg [3:0] shift_in = 4'b1110;
  20
  21     always @ (negedge counter[13]) begin
  22
  23         shift_in <= { shift_in[2:0], shift_in[3] };
  24
  25     end
  26
  27     assign IN_C = shift_in;
  28
  29     reg [15:0] buttons = 0;
  30
  31     always @ (posedge counter[13]) begin
  32
  33         case (shift_in)
  34             4'b1110: begin
  35                 buttons[0] <= !IN_R[0];
  36                 buttons[4] <= !IN_R[1];
  37                 buttons[8] <= !IN_R[2];
  38                 buttons[12] <= !IN_R[3];
  39             end
  40             4'b1101: begin
  41                 buttons[1] <= !IN_R[0];
  42                 buttons[5] <= !IN_R[1];
  43                 buttons[9] <= !IN_R[2];
  44                 buttons[13] <= !IN_R[3];
  45             end
  46             4'b1011: begin
  47                 buttons[2] <= !IN_R[0];
  48                 buttons[6] <= !IN_R[1];
  49                 buttons[10] <= !IN_R[2];
  50                 buttons[14] <= !IN_R[3];
  51             end
  52             4'b0111: begin
  53                 buttons[3] <= !IN_R[0];
  54                 buttons[7] <= !IN_R[1];
  55                 buttons[11] <= !IN_R[2];
  56                 buttons[15] <= !IN_R[3];
  57             end
  58         endcase
  59
  60     end
  61
  62     // Connect up the processor
  63
  64    PROCESSOR cpu(.clk(CLK),//counter[20]),
  65                                  .led(led),
  66                                  .indicators(IND),
  67                                  .uart_tx(UART_TX),
  68                                  .uart_rx(UART_RX),
  69                                  .buttons(buttons));
  70
  71     // Handle output stuff
  72
  73     reg [7:0] out;
  74
  75     reg [2:0] shift_out = 3'b001;
  76
  77     always @ (posedge counter[7]) begin
  78
  79         if (shift_out[2] == 1)
  80             out <= led[7:0];
  81         if (shift_out[0] == 1)
  82             out <= led[15:8];
  83         if (shift_out[1] == 1)
  84             out <= led[23:16];
  85
  86         shift_out <= { shift_out[1:0], shift_out[2] };
  87
  88    end
  89
  90    assign OUT_R = shift_out;
  91
  92    assign OUT_C = out;
  93
  94 endmodule
  95
  96