//---------------------------------------------------------------------------- 2 // Decode rotary encoder to clk-syncronous signals 3 // 4 // (c) Joerg Bornschein (<jb@capsec.org>) 5 //---------------------------------------------------------------------------- 6  7 module rotary ( 8         input        clk, 9         input        reset, 10         input [2:0]  rot, 11         // 12         output reg   rot_btn, 13         output reg   rot_event, 14         output reg   rot_left 15 ); 16  17 //---------------------------------------------------------------------------- 18 // decode rotary encoder 19 //---------------------------------------------------------------------------- 20 reg [1:0] rot_q; 21  22 always @(posedge clk) 23 begin 24         case (rot[1:0]) 25                 2'b00: rot_q <= { rot_q[1], 1'b0 }; 26                 2'b01: rot_q <= { 1'b0, rot_q[0] }; 27                 2'b10: rot_q <= { 1'b1, rot_q[0] }; 28                 2'b11: rot_q <= { rot_q[1], 1'b1 }; 29         endcase 30 end 31  32 reg [1:0] rot_q_delayed; 33  34 always @(posedge clk) 35 begin 36         rot_q_delayed <= rot_q; 37  38         if (rot_q[0] && ~rot_q_delayed[0]) begin 39                 rot_event <= 1; 40                 rot_left  <= rot_q[1]; 41         end else 42                 rot_event <= 0; 43 end 44  45 //---------------------------------------------------------------------------- 46 // debounce push button (rot[2]) 47 //---------------------------------------------------------------------------- 48 reg [2:0]  rot_d; 49 reg [15:0] dead_count; 50  51 always @(posedge clk) 52 begin 53         if (reset) begin 54                 rot_btn    <= 0; 55                 dead_count <= 0; 56         end else begin 57                 rot_btn <= 1'b0; 58                 rot_d   <= { rot_d[1:0], rot[2] }; 59  60                 if (dead_count == 0) begin 61                         if ( rot_d[2:1] == 2'b01 ) begin 62                                 rot_btn    <= 1'b1; 63                                 dead_count <= dead_count - 1; 64                         end 65                 end else 66                         dead_count <= dead_count - 1; 67         end 68 end 69  70 endmodule