module cfg_reg (
  // ===== 标准 APB 总线接口 =====
  input                 pclk,          // APB 时钟
  input                 presetn,       // APB 复位（低有效）
  input  [11:0]         paddr,         // APB 偏移地址
  input                 pwrite,        // 1=写，0=读
  input  [31:0]         pwdata,        // 写数据
  output reg [31:0]     prdata,        // 读数据
  input                 psel,          // 本模块片选
  input                 penable,       // APB使能

  // ===== 输出信号 ADC部分 =====
  output reg            adc_en,            // ADC 使能    
  output reg [7:0]      adc_clk_div,       // 时钟分频
  output reg [3:0]      adc_chnl_sel,      // 通道选择
  output reg [11:0]     trig_threshold,    // 触发阈值
  output reg [15:0]     trig_pulse_width,  // 触发脉宽
  output reg [1:0]      trig_edge,         // 触发边沿（00=上升 01=下降 10=双边 11=脉宽）
  output reg [1:0]      trig_mode,         // 触发模式（00=自动 01=普通 10=单次）
  output reg [4:0]      trig_time_slot,    // 时间档位
  output reg [15:0]     trig_auto_timeout, // 自动模式触发超时值
  output reg            adc_run,           // 开始/停止 
  output reg            adc_restart,       // 重置采样

  // ===== 输出信号 DAC部分 =====
  output reg            dac_en,            // DAC 使能
  output reg            dac_run,           // 运行/停止
  output reg [1:0]      wave_type,         // 波形类型 （00=方波 01=正弦波 10=三角波 11=锯齿波）
  output reg [9:0]      max_vol,           // 最大输出电压（DAC格式）
  output reg [9:0]      min_vol,           // 最小输出电压（DAC格式）
  output reg [31:0]     frequency,         // 频率
  output reg [7:0]      duty_cycle         // 占空比

);

// ==================== ADC 相关 ====================
parameter ADDR_CTRL        = 'h00;
parameter ADDR_CLK_DIV     = 'h04;
parameter ADDR_TRIG_TH     = 'h08;
parameter ADDR_TRIG_PW     = 'h0C;
parameter ADDR_TRIG_CFG    = 'h10;
parameter ADDR_TRIG_TOUT   = 'h14;
parameter ADDR_RUN_CTRL    = 'h18;


// ==================== DAC 相关 ====================
parameter ADDR_DAC_CTRL     = 'h1C;   // DAC 总控
parameter ADDR_DAC_WAVE     = 'h20;   // 波形类型
parameter ADDR_DAC_AMP      = 'h24;   // max + min
parameter ADDR_DAC_FREQ     = 'h28;   // 频率
parameter ADDR_DAC_DUTY     = 'h2C;   // 占空比

wire apb_data_phase = psel && penable;

//---------------------------
// 1. APB 写逻辑
//---------------------------
always @(posedge pclk or negedge presetn) begin
  if (!presetn) begin
    adc_en          <= 1'b0;
    adc_clk_div     <= 8'd3;
    adc_chnl_sel    <= 4'd13;
    trig_threshold  <= 12'd2048;
    trig_pulse_width<= 16'd10;
    trig_edge       <= 2'b00;
    trig_mode       <= 2'b00;
    trig_time_slot  <= 5'd1;
    trig_auto_timeout<=16'd1024;
    adc_run         <= 1'b0;
    adc_restart     <= 1'b0;

    // ==================== DAC 复位 ====================
    dac_en          <= 1'b0;
    dac_run         <= 1'b0;
    wave_type       <= 2'b00;
    max_vol         <= 10'd900;    // 默认最大值
    min_vol         <= 10'd100;    // 默认最小值
    frequency       <= 32'd1000;   // 默认频率
    duty_cycle      <= 8'd50;      // 默认 50%
  end
  else if (apb_data_phase && pwrite) begin
    case (paddr)
      ADDR_CTRL: begin
        adc_en       <= pwdata[0];
        adc_chnl_sel <= pwdata[4:1];
      end
      ADDR_CLK_DIV:   adc_clk_div      <= pwdata[7:0];
      ADDR_TRIG_TH:   trig_threshold   <= pwdata[11:0];
      ADDR_TRIG_PW:   trig_pulse_width <= pwdata[15:0];
      ADDR_TRIG_CFG: begin
        trig_edge      <= pwdata[1:0];
        trig_mode      <= pwdata[3:2];
        trig_time_slot <= pwdata[8:4];
      end
      ADDR_TRIG_TOUT: trig_auto_timeout <= pwdata[15:0];
      ADDR_RUN_CTRL: begin
        adc_run      <= pwdata[0];
        adc_restart  <= pwdata[1];
      end

      // ==================== DAC 写配置 ====================
      ADDR_DAC_CTRL: begin
        dac_en       <= pwdata[0];
        dac_run      <= pwdata[1];
      end
      ADDR_DAC_WAVE:   wave_type      <= pwdata[1:0];
      ADDR_DAC_AMP: begin
        max_vol      <= pwdata[9:0];
        min_vol      <= pwdata[25:16];
      end
      ADDR_DAC_FREQ:   frequency      <= pwdata;
      ADDR_DAC_DUTY:   duty_cycle     <= pwdata[7:0];

    endcase
  end
end

//---------------------------
// 2. APB 读逻辑
//---------------------------
always @(posedge pclk or negedge presetn) begin
  if (!presetn) begin
    prdata <= 32'd0;
  end
  else if (psel && !penable && !pwrite) begin
    case (paddr)
      ADDR_CTRL:     prdata <= {27'd0, adc_chnl_sel, adc_en};
      ADDR_CLK_DIV:  prdata <= {24'd0, adc_clk_div};
      ADDR_TRIG_TH:  prdata <= {20'd0, trig_threshold};
      ADDR_TRIG_PW:  prdata <= {16'd0, trig_pulse_width};
      ADDR_TRIG_CFG: prdata <= {23'd0, trig_time_slot, trig_mode, trig_edge};
      ADDR_TRIG_TOUT:prdata <= {16'd0, trig_auto_timeout};
      ADDR_RUN_CTRL: prdata <= {30'd0, adc_restart, adc_run};


      // ==================== DAC 读 ====================
      ADDR_DAC_CTRL:  prdata <= {30'd0, dac_run, dac_en};
      ADDR_DAC_WAVE:  prdata <= {30'd0, wave_type};
      ADDR_DAC_AMP:   prdata = {6'd0, min_vol, 6'd0, max_vol};
      ADDR_DAC_FREQ:  prdata <= frequency;
      ADDR_DAC_DUTY:  prdata <= {24'd0, duty_cycle};

      default:       prdata <= 32'd0;
    endcase
  end
end

endmodule