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小菜鸟刚刚上路……求指点……用verilog语言写的，用查表法实现NCO，

采用的芯片是Altera公司开发的CycloneIII系列中的EP3C40F484C8芯片，系统时钟为102.4MHz

module FreqMix(
//input interferes
clk,
data_c0,
mgc,
NCO_Switch,
//output interferes
result_c0,
result_c1,
data_sin_r,
data_cos_r);


input clk;
input  [13:0] data_c0;//Sample digital data
input  [7:0] mgc;//demodulation gain
input  [8:0] NCO_Switch;


output  [16:0] result_c0;
output  [16:0] result_c1;


reg [9:0] address_sin;
reg [9:0] address_cos;
wire [17:0] data_sin;
wire [17:0] data_cos;
wire [8:0] Fre_Ctr;


output reg [17:0] data_sin_r;
output reg [17:0] data_cos_r;


reg [13:0] data_buf_c0;


wire [31:0] result_m_c0;
wire [31:0] result_m_c1;


reg [17:0] result_r_c0;
reg [17:0] result_r_c1;


reg [17:0] result_r0_c0;
reg [17:0] result_r0_c1;


always @ (posedge clk)
begin
data_buf_c0 <= data_c0;
end


always @ (posedge clk)
begin
//sin function's address
address_sin<=address_sin+Fre_Ctr;
//cos function's address
address_cos<=address_sin+Fre_Ctr+10'd256;
end


always @ (posedge clk)
begin
data_sin_r<=data_sin;
data_cos_r<=data_cos;
end


RomNCO_Ctr NCO_Ctr
(.clock(clk),.address(NCO_Switch),.q(Fre_Ctr));


//Through LUT,find the sin/cos data
RomFreqMixA  RomFreqMixA_inst
(.address_a(address_sin),.address_b(address_cos),.clock(clk),.q_a(data_sin),.q_b(data_cos));


//Data multiply sin function,result is I signal
MultMix MultMix_inst_c0
(.dataa(data_buf_c0),.datab(data_sin_r),.clock(clk),.result(result_m_c0));


//Data multiply cos function,result is Q signal
MultMix MultMix_inst_c1
(.dataa(data_buf_c0),.datab(data_cos_r),.clock(clk),.result(result_m_c1));


always @ (posedge clk)
begin
case(mgc)
8'h01:begin
result_r_c0<=result_m_c0[29:12];
result_r_c1<=result_m_c1[29:12];
 end
8'h02:begin
result_r_c0<=result_m_c0[28:11];
result_r_c1<=result_m_c1[28:11];
 end
8'h03:begin
result_r_c0<=result_m_c0[27:10];
result_r_c1<=result_m_c1[27:10];
 end
8'h04:begin
result_r_c0<=result_m_c0[26:9];
result_r_c1<=result_m_c1[26:9];
 end
8'h05:begin
result_r_c0<=result_m_c0[25:8];
result_r_c1<=result_m_c1[25:8];
 end


8'h06:begin
result_r_c0<=result_m_c0[24:7];
result_r_c1<=result_m_c1[24:7];
 end
8'h07:begin
result_r_c0<=result_m_c0[23:6];
result_r_c1<=result_m_c1[23:6];
 end
8'h08:begin
result_r_c0<=result_m_c0[22:5];
result_r_c1<=result_m_c1[22:5];
 end
8'h09:begin
result_r_c0<=result_m_c0[21:4];
result_r_c1<=result_m_c1[21:4];
 end
/*8'h0A:begin
result_r_c0<=result_m_c0[20:3];
result_r_c1<=result_m_c1[20:3];
 end
8'h0B:begin
result_r_c0<=result_m_c0[19:2];
  result_r_c1<=result_m_c1[19:2];
 end
8'h0C:begin
result_r_c0<=result_m_c0[18:1];
result_r_c1<=result_m_c1[18:1];
 end
8'h0D:begin
result_r_c0<=result_m_c0[17:0];
result_r_c1<=result_m_c1[17:0];
 end*/
default:begin
result_r_c0<=result_m_c0[30:13];
result_r_c1<=result_m_c1[30:13];
    end


endcase
result_r0_c0<=result_r_c0+18'd1;
result_r0_c1<=result_r_c1+18'd1;
end
//The mode of operation reduces the effects of digital output inerferance
assign result_c0 = result_r0_c0[17:1];
assign result_c1 = result_r0_c1[17:1];
endmodule