module    ad_pro(
        clk,rst_n,
        smg1,smg2,smg3,
        dout,cs_n,din,clk_50k//12.5M
);
input        clk;
input        rst_n;
input        dout;
output    reg    [7:0]        smg1;
output    reg    [7:0]        smg2;
output    reg    [7:0]        smg3;
output    reg        cs_n;
output    reg        din;
output    reg        clk_50k;

//50K时钟
reg        [8:0]        cnt_50k;
always@(negedge clk or negedge rst_n)
    if(!rst_n)begin
        cnt_50k <= ‘d0;
        clk_50k <= ‘d0;
    end
    else if(cnt_50k == 2‘d2)begin        //12.5M
        cnt_50k <= ‘d0;
        clk_50k =~ clk_50k;
    end
    else
        cnt_50k <= cnt_50k + 1‘b1;
        
        
//fsm
parameter    din_regis = 16‘b100_001_110_001_0000;
reg        [3:0]        state;
reg        [15:0]    ad_buffer;
reg        [9:0]        ad_buffer1;
reg        [3:0]        num_din;
reg        [3:0]        num_dout;
reg        [15:0]    temp;    
always @(posedge clk_50k or negedge rst_n)
    if(!rst_n)begin
        cs_n <= 1‘d1;
        din <= 1‘d1;
        state <= ‘d0;
        num_din <= 4‘d15;
        num_dout <= ‘d0;
        ad_buffer <= ‘d0;
        ad_buffer1 <= ‘d0;
    end
    else
    case(state)
    4‘d0:begin
            cs_n <= 1‘d1;
            state <= state + 1‘b1;
            num_din <= 4‘d15;
            num_dout <= 4‘d0;
            ad_buffer <= ‘d0;
            //ad_buffer1 <= ‘d0;
        end
    4‘d1:begin
            //cs_n <= 1‘d0;
            //din <= 1‘d1;
            state <= state + 1‘b1;
        end
    4‘d2:begin   //写寄存器
            cs_n <= 1‘d0;
            din <= (din_regis >> num_din) & 1;
            num_din <= num_din - 1‘b1;
            ad_buffer <= (ad_buffer << 1) | dout;
            num_dout <= num_dout + 1‘b1;
            if(num_dout == 4‘d15 && num_din == 4‘d0)
                state <= state + 1‘b1;
            else
                state <= state;
        end
    4‘d3:begin
            ad_buffer1 <= (ad_buffer[11:4]*100/51);
            cs_n <= 1‘d1;
            state <= 1‘d0;
        end
    endcase
//smg display
//0~9的键值  共阴极
parameter _0=8‘hc0,_1=8‘hf9,_2=8‘ha4,_3=8‘hb0,_4=8‘h99,
             _5=8‘h92,_6=8‘h82,_7=8‘hf8,_8=8‘h80,_9=8‘h90;
always @(posedge clk or negedge rst_n)
    if(!rst_n)begin
        smg1 <= 8‘h0;
    end
    else 
    case(ad_buffer1/100)
    4‘d0:smg1 <= _0;
    4‘d1:smg1 <= _1;
    4‘d2:smg1 <= _2;
    4‘d3:smg1 <= _3;
    4‘d4:smg1 <= _4;
    4‘d5:smg1 <= _5;
    4‘d6:smg1 <= _6;
    4‘d7:smg1 <= _7;
    4‘d8:smg1 <= _8;
    4‘d9:smg1 <= _9;
    endcase
    
always @(posedge clk or negedge rst_n)
    if(!rst_n)begin
        smg2 <= 8‘h0;
    end
    else 
    case(ad_buffer1%100/10)
    4‘d0:smg2 <= _0;
    4‘d1:smg2 <= _1;
    4‘d2:smg2 <= _2;
    4‘d3:smg2 <= _3;
    4‘d4:smg2 <= _4;
    4‘d5:smg2 <= _5;
    4‘d6:smg2 <= _6;
    4‘d7:smg2 <= _7;
    4‘d8:smg2 <= _8;
    4‘d9:smg2 <= _9;
    endcase

always @(posedge clk or negedge rst_n)
    if(!rst_n)begin
        smg3 <= 8‘h0;
    end
    else 
    case(ad_buffer1%10)
    4‘d0:smg3 <= _0;
    4‘d1:smg3 <= _1;
    4‘d2:smg3 <= _2;
    4‘d3:smg3 <= _3;
    4‘d4:smg3 <= _4;
    4‘d5:smg3 <= _5;
    4‘d6:smg3 <= _6;
    4‘d7:smg3 <= _7;
    4‘d8:smg3 <= _8;
    4‘d9:smg3 <= _9;
    endcase




endmodule