上一篇寫了基于Xilinx FPGA的通用信號發生器的案例，反響比較好，很多朋友和我探討相關的技術，其中就涉及到信號的采集，為了使該文更有血有肉，我在寫一篇基于Xilinx FPGA的通用信號采集器，望能形成呼應，以解答大家的疑問。目的：1.通過設計實現信號采集與分析，掌握組合邏輯設計方法；2.通過設計實現信號的采集與分析，掌握信號采集原理。原理：利用FPGA芯片，用verilog語言編寫邏輯，控制AD0809進行AD轉換。AD0809是帶有8位AD轉換器、8路多路開關以及微處理機兼容的控制邏輯的CMOS組件，它是逐次逼近式的AD轉換器。AD0809的內部結構圖如下：

由上圖可知，多路開關可選通8 個模擬通道，允許8路模擬量分時輸入，共用AD轉換器進行轉換，三態輸出鎖存器用于鎖存AD轉換完成后的數字量，當OE為高時才可以從鎖存器取出轉換后的數據。通道選擇如下圖所示：

START為轉換啟動信號。當START上跳沿時，所有內部寄存器清零；下跳沿時，開始進行A/D 轉換；在轉換期間，START應保持低電平。EOC 為轉換結束信號。當EOC 為高電平時，表明轉換結束；否則，表明正在進行A/D 轉換。OE為輸出允許信號，用于控制三條輸出鎖存器向單片機輸出轉換得到的數據。OE＝1，輸出轉換得到的數據；OE＝0，輸出數據線呈高阻狀態。時序如下圖所示：

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254源代碼1.Verilog源代碼，dataCollect.vmodule dataCollect(sysclk, rst, adda, addb, addc, start, oe, ????????datain, led_sel, led_seg);????input sysclk, rst;????input wire [7:0] datain;????output reg adda, addb, addc, start, oe;????output reg[3:0] led_sel;????output reg[7:0] led_seg;?????reg [3:0] counter1;????reg [7:0] readdata;?????reg [9:0] counter2;????reg [15:0] sum;????reg [7:0] averdata;?????reg [7:0] temp;????reg [3:0] dataout1, dataout2, dataout3;?????reg [3:0] counter3;?????parameter ZERO = 8'b11111100,ONE = 8'b01100000, TWO = 8'b11011010;????parameter THREE = 8'b11110010, FOUR =8'b01100110;????parameter FIVE = 8'b10110110, SIX = 8'b10111110, SEVEN =8'b11100000;????parameter EIGHT = 8'b11111110, NINE = 8'b11110110, BLANK = 8'b00000000;??????always @(posedge sysclk or negedge rst)????begin????????if (!rst)????????begin????????????adda = 0;????????????addb = 0;????????????addc = 0;?????????????oe = 1;?????????????counter1 = 0;????????end????????else????????begin????????????counter1 = counter1 + 1;????????????case (counter1)????????????????3 : start = 0;????????????????4 : start = 1;????????????????5 : start = 0;????????????????10 : readdata = datain;????????????????15 : counter1 = 0;????????????????default : counter1 = counter1;????????????endcase????????end????end?????always @(posedge sysclk or negedge rst)????begin????????if (!rst)????????begin????????????counter2 = 0;????????????sum = 0;????????????averdata = 0;????????end????????else????????begin????????????counter2 = counter2 + 1;????????????if ((counter2%16) == 0)????????????????sum = sum + readdata;????????????else if (counter2 > 512)????????????begin????????????????averdata = sum / 32;????????????????sum = 0;????????????????counter2 = 0;????????????end????????end????end??????always @(averdata)????begin????????temp = averdata;????????if (temp > 199)????????????dataout3 = 2;????????else if (temp > 99)????????????dataout3 = 1;????????else????????????dataout3 = 0;????????????????temp = temp - dataout3 * 100;????????if (temp > 89)????????????dataout2 = 9;????????else if (temp > 79)????????????dataout2 = 8;????????else if (temp > 69)????????????dataout2 = 7;????????else if (temp > 59)????????????dataout2 = 6;????????else if (temp > 49)????????????dataout2 = 5;????????else if (temp > 39)????????????dataout2 = 4;????????else if (temp > 29)????????????dataout2 = 3;????????else if (temp > 19)????????????dataout2 = 2;????????else if (temp > 9)????????????dataout2 = 1;????????else????????????dataout2 = 0;?????????temp = temp - dataout2 * 10;????????dataout1 = temp;?????????if ((dataout3==0) && (dataout2==0))????????begin????????????dataout3 = 10;????????????dataout2 = 10;????????end????????else if (dataout3 == 0)????????????dataout3 = 10;????????else????????????dataout3 = dataout3;????end??????always @(posedge sysclk or negedge rst)????begin????????if (!rst)????????begin????????????counter3 = 0;????????????led_sel = 4'b0001;????? ????????end????????else????????begin????????????????if (counter3 == 4)????????????????begin????????????????????counter3 = 0;????????????????????if (led_sel == 4'b1000)????????????????????????led_sel = 4'b0001;????????????????????else????????????????????????led_sel = led_sel << 1;????????????????end????????????????counter3 = counter3 + 1;????????end????????????end?????always @(led_sel, dataout1, dataout2, dataout3)????begin????????case (led_sel)????????????4'b0001 :????????????begin????????????????case (dataout1)????????????????????0 : led_seg = ZERO;????????????????????1 : led_seg = ONE;????????????????????2 : led_seg = TWO;????????????????????3 : led_seg = THREE;????????????????????4 : led_seg = FOUR;????????????????????5 : led_seg = FIVE;????????????????????6 : led_seg = SIX;????????????????????7 : led_seg = SEVEN;????????????????????8 : led_seg = EIGHT;????????????????????9 : led_seg = NINE;????????????????????default : led_seg = BLANK;????????????????endcase????????????end????????????4'b0010 :????????????begin????????????????case (dataout2)????????????????????0 : led_seg = ZERO;????????????????????1 : led_seg = ONE;????????????????????2 : led_seg = TWO;????????????????????3 : led_seg = THREE;????????????????????4 : led_seg = FOUR;????????????????????5 : led_seg = FIVE;????????????????????6 : led_seg = SIX;????????????????????7 : led_seg = SEVEN;????????????????????8 : led_seg = EIGHT;????????????????????9 : led_seg = NINE;????????????????????default : led_seg = BLANK;????????????????endcase????????????end????????????4'b0100 :????????????begin????????????????case (dataout3)????????????????????0 : led_seg = ZERO;????????????????????1 : led_seg = ONE;????????????????????2 : led_seg = TWO;????????????????????3 : led_seg = THREE;????????????????????4 : led_seg = FOUR;????????????????????5 : led_seg = FIVE;????????????????????6 : led_seg = SIX;????????????????????7 : led_seg = SEVEN;????????????????????8 : led_seg = EIGHT;????????????????????9 : led_seg = NINE;????????????????????default : led_seg = BLANK;????????????????endcase????????????end????????????4'b1000 :????????????begin????????????????case (10)????????????????????0 : led_seg = ZERO;????????????????????1 : led_seg = ONE;????????????????????2 : led_seg = TWO;????????????????????3 : led_seg = THREE;????????????????????4 : led_seg = FOUR;????????????????????5 : led_seg = FIVE;????????????????????6 : led_seg = SIX;????????????????????7 : led_seg = SEVEN;????????????????????8 : led_seg = EIGHT;????????????????????9 : led_seg = NINE;????????????????????default : led_seg = BLANK;????????????????endcase????????????end????????????default :????????????begin????????????????led_seg = 1'hx;????????????end????????endcase????end?endmodule?2.引腳分配源代碼，dataCollect.ucfnet sysclk loc = p80;net rst loc = p57;?net adda loc = p14;net addb loc = p16;net addc loc = p18;?net oe loc = p23;net start loc = p27;?net datain<7> loc = p30;net datain<6> loc = p33;net datain<5> loc = p35;net datain<4> loc = p37;net datain<3> loc = p42;net datain<2> loc = p44;net datain<1> loc = p46;net datain<0> loc = p48;?net led_sel<3> loc = p3;net led_sel<2> loc = p5;net led_sel<1> loc = p7;net led_sel<0> loc = p9;?net led_seg<7> loc = p206;net led_seg<6> loc = p204;net led_seg<5> loc = p202;net led_seg<4> loc = p200;net led_seg<3> loc = p195;net led_seg<2> loc = p193;net led_seg<1> loc = p191;net led_seg<0> loc = p187;?OK了，可以使用了，按照為器件分配的引腳進行連線，系統時鐘輸入連1KMHZ，可以旋轉電位器以改變輸入電壓,此時可觀察到數據管上數據變化。FPGA，融入其中，樂趣無窮。。。。