`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company: 
// Engineer: 
// 
// Create Date: 09/10/2021 11:42:33 AM
// Design Name: 
// Module Name: heartbeat_mode
// Project Name: 
// Target Devices: 
// Tool Versions: 
// Description: 
// 
// Dependencies: 
// 
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
// 
//////////////////////////////////////////////////////////////////////////////////


module pwm_heartbeat_mode #(
  parameter Resolution = 16
) (
  input                         clk_i,
  input                         rst_ni,
  input       [Resolution-1:0]  threshold_counter_1,
  input       [Resolution-1:0]  threshold_counter_2,
  input       [Resolution-1:0]  period_counter,
  input       [Resolution-1:0]  step,
  input       [Resolution-1:0]  increment_step,
  output                        pwm_signal
);

  reg                      direction;
  reg   [Resolution-1:0]   counter;
  reg   [Resolution-1:0]   counter_temp;
  reg   [Resolution-1:0]   smaller_number_reg;
  reg   [Resolution-1:0]   larger_number_reg;
  wire  [Resolution-1:0]   smaller_number;
  wire  [Resolution-1:0]   larger_number;
  
  
  pwm_standard_mode #(
    .Resolution         (Resolution)
  ) standard_mode_pwm (
    .clk_i              (clk_i),
    .rst_ni             (rst_ni),
    .threshold_counter  (counter),
    .period_counter     (period_counter),
    .step               (step),
    .pwm_signal         (pwm_signal)
  );
  
  pwm_find_smaller #(
    .Resolution         (Resolution)
  ) find_smaller_number (
    .number_1           (threshold_counter_1),
    .number_2           (threshold_counter_2),
    .smaller_number     (smaller_number),
    .larger_number      (larger_number)
  );
  
  always @(posedge clk_i) begin
    if (rst_ni == 0) begin
      smaller_number_reg <= 0;
      larger_number_reg  <= 0;
    end else begin
      smaller_number_reg <= smaller_number;
      larger_number_reg  <= larger_number;
    end
  end
  
  always @(posedge clk_i) begin
    if (rst_ni == 0) begin
      counter_temp <= 0;
      counter      <= 0;
      direction    <= 0;
    end else begin
      if (counter_temp < period_counter) begin
        counter_temp <= counter_temp + 1;
        counter      <= counter;
        direction    <= direction;
      end else begin
        counter_temp <= 0;
        if (counter == 0 || smaller_number_reg != smaller_number || larger_number_reg != larger_number) begin
          counter   <= smaller_number;
          direction <= 0;
        end else begin
          if (counter > (larger_number_reg-increment_step) && direction == 0) begin
            counter <= counter - increment_step;
            direction <= 1;
          end else if (counter < (smaller_number_reg+increment_step) && direction == 1) begin
            counter <= counter + increment_step;
            direction <= 0;
          end else begin
            if (direction == 0) begin
              counter <= counter + increment_step;
            end else begin
              counter <= counter - increment_step;
            end
          end
        end
      end
    end       
  end
endmodule