cariboulabs-cariboulite/firmware/lvds_rx.v

module lvds_rx
    (
        input               i_rst_b,
        input               i_ddr_clk,
        input [1:0]         i_ddr_data,

        input               i_fifo_full,
        output              o_fifo_write_clk,
        output              o_fifo_push,
        output reg [31:0]   o_fifo_data,
		input				i_sync_input,
        output [1:0]        o_debug_state );

    // Internal FSM States
    localparam
        state_idle   = 3'b00,
        state_i_phase = 3'b01,
        state_q_phase = 3'b11;

    // Modem sync symbols
    localparam
        modem_i_sync  = 3'b10,
        modem_q_sync = 3'b01;

    // Internal Registers
    reg [1:0]   r_state_if;
    reg [2:0]   r_phase_count;
    reg         r_cnt;
	reg			r_sync_input;

    assign o_debug_state = r_state_if;

    // Initial conditions
    initial begin
        r_state_if = state_idle;
        r_phase_count = 3'b111;
    end

    // Global Assignments
    assign o_fifo_write_clk = i_ddr_clk;

    // Main Process
    always @(posedge i_ddr_clk or negedge i_rst_b)
    begin
        if (i_rst_b == 1'b0) begin
            r_state_if <= state_idle;
            o_fifo_push <= 1'b0;
            r_phase_count <= 3'b111;
            r_cnt <= 0;
			r_sync_input <= 1'b0;
        end else begin
            case (r_state_if)
                state_idle: begin
                    if (i_ddr_data == modem_i_sync) begin
                        r_state_if <= state_i_phase;
						o_fifo_data <= {30'b000000000000000000000000000000, i_ddr_data};
						r_sync_input <= i_sync_input;
                    end
                    r_phase_count <= 3'b111;
                    o_fifo_push <= 1'b0;
                end

                state_i_phase: begin
                    if (r_phase_count == 3'b000) begin
                        if (i_ddr_data == modem_q_sync ) begin
                            r_phase_count <= 3'b110;
                            r_state_if <= state_q_phase;
                        end else begin
                            r_state_if <= state_idle;
                        end
                    end else begin
                        r_phase_count <= r_phase_count - 1;
                    end

					o_fifo_push <= 1'b0;
                    o_fifo_data <= {o_fifo_data[29:0], i_ddr_data};
                end

                state_q_phase: begin
                    if (r_phase_count == 3'b000) begin
                        o_fifo_push <= ~i_fifo_full;
                        r_state_if <= state_idle;
						o_fifo_data <= {o_fifo_data[29:0], i_ddr_data[1], r_sync_input};
                    end else begin
						o_fifo_push <= 1'b0;
                        r_phase_count <= r_phase_count - 1;
						o_fifo_data <= {o_fifo_data[29:0], i_ddr_data};
                    end
                    
                end
            endcase
        end
    end

endmodule


/*
module lvds_rx (input               i_rst_b,
				input               i_ddr_clk,
				input [1:0]         i_ddr_data,

				input               i_fifo_full,
				output              o_fifo_write_clk,
				output              o_fifo_push,
				output reg [31:0]   o_fifo_data,
				input				i_sync_input,
				output [1:0]        o_debug_state );


    // Internal FSM States
    localparam
        state_idle   = 3'b00,
        state_i_phase = 3'b01,
        state_q_phase = 3'b11;

    // Modem sync symbols
    localparam
        modem_i_sync  = 3'b10,
        modem_q_sync = 3'b01;

    // Internal Registers
    reg [1:0]   r_state_if;
    reg [3:0]   r_phase_count;

    assign o_debug_state = r_state_if;

    // Initial conditions
    initial begin
        r_state_if = state_idle;
        r_phase_count = 4'd15;
    end

    // Global Assignments
    assign o_fifo_write_clk = i_ddr_clk;

    // Main Process
    // Data structure from the modem:
    //	[S'10'] [13'I] ['0'] [S'01'] [13'Q] ['0']
    // Data structure with out sync 's'
    //	['10'] [I] ['0'] ['01'] [Q] ['s']
    always @(posedge i_ddr_clk or negedge i_rst_b)
    begin
        if (i_rst_b == 1'b0) begin
            r_state_if <= state_idle;
            r_phase_count <= 4'd15;
            o_fifo_push <= 1'b0;
        end else begin           
            case (r_state_if)
                state_idle: begin
                    if (i_ddr_data == modem_i_sync ) begin
                        r_state_if <= state_i_phase;
                    end
                    r_phase_count <= 4'd15;
                end

                state_i_phase: begin
                    if (r_phase_count == 4'd8) begin
                        if (i_ddr_data == modem_q_sync ) begin
                            r_state_if <= state_q_phase;
                        end else begin
                            r_state_if <= state_idle;
                        end
                    end
                    r_phase_count <= r_phase_count - 1;
                end

                state_q_phase: begin
                    if (r_phase_count == 4'd1) begin
                        r_state_if <= state_idle;
                    end
                    
                    r_phase_count <= r_phase_count - 1;
                end
            endcase
            
            o_fifo_data <= {o_fifo_data[29:0], i_ddr_data};
            o_fifo_push <= r_phase_count == 4'd0 && ~i_fifo_full;
        end
    end

endmodule
*/