PS2Button.v

   1 module PS2Button(
   2         input clk,
   3         input inclk,
   4         input indata,
   5         output wire [7:0] buttons
   6         );
   7
   8         reg [3:0] bitcount = 0;
   9         reg [7:0] key = 0;
  10         reg keyarrow = 0, keyup = 0, parity = 0;
  11         reg key_a = 0,key_b = 0,key_st = 0,key_sel = 0,key_up = 0,key_dn = 0,key_l = 0,key_r = 0;
  12
  13         assign buttons = {key_st,key_sel,key_b,key_a,key_dn,key_up,key_l,key_r};
  14
  15         /* Clock debouncing */
  16         reg lastinclk = 0;
  17         reg [5:0] debounce = 0;
  18         reg fixedclk = 0;
  19         reg [9:0] resetcountdown = 0;
  20
  21         always @(posedge clk) begin
  22                 if (inclk != lastinclk) begin
  23                         lastinclk <= inclk;
  24                         debounce <= 1;
  25                         resetcountdown <= 10'b1111111111;
  26                 end else if (debounce == 0) begin
  27                         fixedclk <= inclk;
  28                         resetcountdown <= resetcountdown - 1;
  29                 end else
  30                         debounce <= debounce + 1;
  31         end
  32
  33         always @(negedge fixedclk) begin
  34                 if (resetcountdown == 0)
  35                         bitcount <= 0;
  36                 else if (bitcount == 10) begin
  37                         bitcount <= 0;
  38                         if(parity != (^ key)) begin
  39                                 if(keyarrow) begin
  40                                         keyarrow <= 0;
  41                                         case(key)
  42                                                 8'hF0: keyup <= 1;
  43                                                 8'h75: key_up <= 1;
  44                                                 8'h74: key_r <= 1;
  45                                                 8'h72: key_dn <= 1;
  46                                                 8'h6B: key_l <= 1;
  47                                         endcase
  48                                 end
  49                                 else begin
  50                                         if(keyup) begin
  51                                                 keyup <= 0;
  52                                                 case(key)
  53                                                         8'h75: key_up <= 0;
  54                                                         8'h74: key_r <= 0;
  55                                                         8'h72: key_dn <= 0;
  56                                                         8'h6B: key_l <= 0;
  57                                                         8'h1C: key_a <= 0;
  58                                                         8'h1B: key_b <= 0;
  59                                                         8'h5A: key_st <= 0;
  60                                                         8'h59: key_sel <= 0;
  61                                                 endcase
  62                                         end
  63                                         else begin
  64                                                 case(key)
  65                                                         8'hE0: keyarrow <= 1;
  66                                                         8'hF0: keyup <= 1;
  67                                                         8'h1C: key_a <= 1;
  68                                                         8'h1B: key_b <= 1;
  69                                                         8'h5A: key_st <= 1;
  70                                                         8'h59: key_sel <= 1;
  71                                                 endcase
  72                                         end
  73                                 end
  74                         end
  75                         else begin
  76                                 keyarrow <= 0;
  77                                 keyup <= 0;
  78                                 {key_a,key_b,key_st,key_sel,key_up,key_dn,key_l,key_r} <= 8'b0;
  79                         end
  80                 end else
  81                         bitcount <= bitcount + 1;
  82
  83                 case(bitcount)
  84                         1: key[0] <= indata;
  85                         2: key[1] <= indata;
  86                         3: key[2] <= indata;
  87                         4: key[3] <= indata;
  88                         5: key[4] <= indata;
  89                         6: key[5] <= indata;
  90                         7: key[6] <= indata;
  91                         8: key[7] <= indata;
  92                         9: parity <= indata;
  93                 endcase
  94         end
  95
  96 endmodule