Subversion Repositories q_rotary_enc

/*
        Counter for quadrature rotary encoder with low-pass filter
*/

`ifndef _rot_enc_flt_
`define _rot_enc_flt_
`include "lpf_cap.sv"
`include "q_rotary_enc.sv"

module rot_enc_flt(
        input clock,
        input sclr,
        input dir, // main direction
        input A, B,
        output signed [31:0] bidir_counter,
        output error,
        output ready // counter enabled
);
        reg A_reg = 1'b0, B_reg = 1'b0;
        wire A_flt, B_flt;
        reg [1:0] dir_reg = '0;
        wire dir_changed;
        wire [1:0] init;        
        
        // to trigger A, B signals on input pins
        always_ff @(posedge clock) begin
                A_reg <= A;
                B_reg <= B;
                dir_reg <= {dir_reg[0], dir};
        end             
                
        assign dir_changed = dir_reg[1] ^ dir_reg[0];
        
        // debouncing
        lpf_cap #(7) // 2^7 - it's about 1/8 of min encoder period
                f0(.clock, .sclr(dir_changed), .in(A_reg), .out(A_flt), .init(init[0])),
                f1(.clock, .sclr(dir_changed), .in(B_reg), .out(B_flt), .init(init[1]));
        
        reg ready_reg = 1'b0;
        always_ff @(posedge clock)
                ready_reg <= (dir_changed) ? 1'b0 : init == '0;
        
        assign ready = ready_reg;
        
        q_rotary_enc enc_inst(
                .clock, .sclr(sclr || dir_changed), .ena(init == '0), .dir(dir_reg[0]),
                .A(A_flt), .B(B_flt),
                .bidir_counter,
                .error
        );

endmodule :rot_enc_flt

`endif