Subversion Repositories q_rotary_enc

timeunit 1ns;

timeprecision 100ps;

module rot_enc_flt_tb;

        bit clock = 0, sclr = 1;

        wire A, B;

        bit dir = 0;

        wire signed [31:0] bidir_counter;

        wire error;

        wire ready;

        always #10ns clock++;

        bit rot_dir = 0, run = 0;

        initial begin

                repeat(10) @(posedge clock);

                sclr = 1'b0;

                wait(ready);

                repeat(10_000) @(posedge clock);

                rot_dir = 0;

                run = 1;

                #1ms

                run = 0;

                #500us

                rot_dir = 1;

                run = 1;

                #1ms

                run = 0;

                repeat(10_000) @(posedge clock);

                $stop(2);

        end

        rot_enc_flt dut(.*);

        rotary_sensor sensor(.clock, .run, .rot_dir, .A, .B);

endmodule :rot_enc_flt_tb

module rotary_sensor(input clock, run, rot_dir, output A, B);

        bit[1:0] gray[4] = {2'b00, 2'b01, 2'b11, 2'b10};

        localparam BPS = 10_000 * 256 * 4 / 60;

        localparam CLOCK_MHZ = 50_000_000;

        localparam CNT_MAX = CLOCK_MHZ / BPS - 1;

        int bit_cnt = 0;

        always_ff @(posedge clock)

                if (bit_cnt == CNT_MAX)

                        bit_cnt <= 0;

                else

                        bit_cnt <= bit_cnt + 1;

        wire bit_clk = bit_cnt == CNT_MAX;

        bit [1:0] gray_cnt = 0;

        always_ff @(posedge clock)

                if (bit_clk && run)

                        if (rot_dir == 0)

                                gray_cnt <= gray_cnt + 1'b1;

                        else

                                gray_cnt <= gray_cnt - 1'b1;

        assign {B, A} = gray[gray_cnt];

endmodule :rotary_sensor