source: trunk/MultiChannelUSB/analyser.v@ 68

module analyser
        (
                input   wire                    clk, reset,
                input   wire                    data_ready,
                input   wire    [1:0]   uwt_flag,
                input   wire    [11:0]  uwt_data,
                input   wire    [11:0]  threshold,
                output  wire                    peak_ready,
                output  wire    [11:0]  peak
        );

        reg             [1:0]   state_reg, state_next;
        reg             [3:0]   counter_reg, counter_next;
        reg                             peak_ready_reg, peak_ready_next;
        reg             [11:0]  peak_reg, peak_next;
        reg             [15:0]  buffer [15:0];
        wire    [15:0]  sample;
        wire    [11:0]  baseline;

        integer                 i;

        assign  sample = {4'd0, uwt_data};
        assign  baseline = buffer[15][15:4];
        
        always @(posedge clk)
        begin
                if (reset)
                begin
                        state_reg <= 2'd0;
                        counter_reg <= 4'd0;
                        peak_ready_reg <= 1'b0;
                        peak_reg <= 12'd0;

                        for(i = 0; i <= 15; i = i + 1)
                        begin
                                buffer[i] <= 12'd0;
                        end
                end
                else
                begin
                        state_reg <= state_next;
                        counter_reg <= counter_next;
                        peak_ready_reg <= peak_ready_next;
                        peak_reg <= peak_next;
                        
                        if (data_ready & uwt_flag[1])
                        begin
                                for(i = 0; i < 15; i = i + 1)
                                begin
                                        buffer[i+1] <= buffer[i] + sample;
                                end
                                buffer[0] <= sample;
                        end
                end
        end
        
        always @*
        begin
                state_next = state_reg;
                counter_next = counter_reg;
                peak_ready_next = peak_ready_reg;
                peak_next = peak_reg;
                case (state_reg)
                        0: // skip first 16 samples
                        begin
                                peak_next = 12'd0;
                                peak_ready_next = 1'b0;
                                if (data_ready)
                                begin
                                        counter_next = counter_reg + 4'd1;
                                        if (&counter_reg)
                                        begin
                                                state_next = 2'd1;
                                        end
                end
                        end

                        1: // skip first 16 minima
                        begin
                                if (data_ready & uwt_flag[1])
                                begin
                                        counter_next = counter_reg + 4'd1;
                                        if (&counter_reg)
                                        begin
                                                state_next = 2'd2;
                                        end
                end
                        end

                        2: // calculate peak height
                        begin
                                if (data_ready & uwt_flag[0])
                                begin
                                        peak_next = (uwt_data > baseline) ? (uwt_data - baseline) : 12'd0;
                                        peak_ready_next = (peak_next > threshold);
                end
                else
                begin
                                        peak_ready_next = 1'b0;
                                end
                        end

                        default:
                        begin
                                peak_next = 12'd0;
                                peak_ready_next = 1'b0;
                                state_next = 2'd0;
                        end
                endcase
        end

        assign  peak_ready = peak_ready_reg;
        assign  peak = peak_reg;
endmodule