数字逻辑创新性实验电子琴

1、数字逻辑实验电子琴一、实验目的1 了解乐曲演奏电路的工作原理；2 了解怎样控制音调和音长的变化，掌握乐曲演奏电路的设计方法；3 进一步熟悉数字逻辑实验的设计思想，学会在原实验基础上进行创新。二、实验创新点1.本实验将乐曲演奏电路新增加了一个用户子弹奏模块，变为电子琴；2.本实验利用公式计算出了所有半音的分频系数和预置数，并应用到歌曲中；3.本实验中的电子琴模块，当选择不同的按键时，可以再7段数码显示管上显示相应的数字，即：1(do)、2(re)、3(mi)、4(fa)、5(sol)、6(la)、7(si)、8(song)。三、实验原理1.乐理的基础知识唱名（Syllable names）唱名是

2、指在音阶上各音的名称。通常使用1do、2re、3mi、4fa、5sol、6la、7si。2.音调的控制频率的高低决定了音调的高低，相邻两个半音之间的频率之比为2的12次根。根据这点，可以计算出简谱中从低音1到高音7之间每个唱名对应的频率如表所示：音名频率（Hz）音名频率（Hz）音名频率（Hz）低音1261.63中音1523.25高音11046.50低音2293.67中音2587.33高音21174.66低音3329.63中音3659.25高音31381.51低音4349.23中音4698.46高音41396.92低音5391.99中音5783.99高音51567.98低音6440中音6880高

3、音61760低音7439.88中音7987.76高音71975.52本实验选取6MHz为基准频率，采用加载预置数法。先使分频计数器在输入时钟的作用下开始加1计数，当计到最大值时，则加载一个预置数（预置数=计数器最大值-分频系数）；然后使分频计数器在预置数的基础上开始加1计数，当计到最大值时，则又加载预置数。这样使计数器的计数长度实际就是分频系数的值。每次当分频计数器计到最大值时，产生分频后的输出时钟信号。下表列出了所有唱名（包括半音）对应的分频系数及分频计数器的预置数。唱名的分频系数=3MHz/唱名频率；预置数=计数器最大值-分频系数=16383-分频系数；唱名分频系数预置数唱名分频系数预置数

4、唱名分频系数预置数低音1114684915中音1573410649高音1286713516低音b2108245559中音b2541210971高音b2270613677低音2102176166中音2510811275高音2255413829低音b396436740中音b3482211561高音b3241113972低音391027281中音3455111832高音3227614107低音485917792中音4429612087高音4214814235低音b581098274中音b5405512328高音b5202714356低音576548729中音5382712556高音519131447

5、0低音b672249159中音b6361212771高音b6180614577低音668199564中音6340912974高音6170514678低音b764369947中音b7321813165高音b7160914774低音7607510308中音7303713346高音7151914864此外，对于乐曲中的休止符，只要将分频系数设为0，使其对应的预置数为16383即可，此时扬声器不会发声。3.音长的控制在本实验中，电子琴中预先存放着一首歌曲梁祝，按下相应的键即可让电子琴自动演奏乐曲，在这个片段中，最短的音符为4分音符，如果将全音符的持续时间设为1s，则只需再提供一个4Hz的时钟频率即可产

6、生4分音符的时长。四、实验步骤：1总体设计思路电子琴的原理图如下：包括自动播放子模块和自弹奏子模块。在弹奏过程中，通过拨动L1-L7，即可实现对应的“do-si”，并且通过数码管显示1-7（表示现在正为自弹奏功能）。拨动L8，即为自动播放模块，此时扬声器自动播放乐曲梁祝片段，并且数码管显示数字8（表示正为自动播放功能），如果数码管显示为0，则说明处于待机状态，进行演奏。数码管显示自动播放模块电子琴模块（译码器原理）与门Clk_6MHzspeakerabcdefg与门自弹模块（手动）Clk_4Hzclrstartstop2.电子琴模块piano.v的设计电子琴模块功能框图如下：（1）自动播放模块

7、：扬声器2分频器反馈预置计数器6MHz预置数产生16Hz其中反馈预置计数器对基准频率6MHz进行分频，产生分频后的输出时钟信号。计数器需加载的预置数由预置数产生电路产生。反馈预置计数器产生的输出时钟再经过2分频器，成为方波信号，以驱动扬声器发声。（2）自弹奏模块L1L2L3L4L5L6L7L8自弹奏模块speaker123456780五、实验代码：piano.vmodule piano(in,clk_6MHz,clk_4Hz,song,speaker,a,b,c,d,e,f,g); input in,clk_6MHz,clk_4Hz,song; output speaker; output a

8、,b,c,d,e,f,g;reg speaker;reg a,b,c,d,e,f,g;reg7:0 state; reg song_on; wire6:0 in; reg3:0 high,med,low; reg13:0 divider,origin; reg7:0 counter; reg out; wire carry; reg20:0 i; parameter zero=8'b0000_0000, one=8'b0000_0001, two=8'b0000_0010, three=8'b0000_0100, four=8'b0000_1000, f

9、ive=8'b0001_0000, six=8'b0010_0000, seven=8'b0100_0000; initial begin song_on<=0; end always (posedge song) begin song_on<=song_on; end always(in)beginif(song_on)a,b,c,d,e,f,g=7'b1111111;elsecase(in)zero:a,b,c,d,e,f,g=7'b1111110;one:a,b,c,d,e,f,g=7'b0110000;two:a,b,c,d,

10、e,f,g=7'b1101101;three:a,b,c,d,e,f,g=7'b1111001;four:a,b,c,d,e,f,g=7'b0110011;five:a,b,c,d,e,f,g=7'b1011011;six:a,b,c,d,e,f,g=7'b1011111;seven:a,b,c,d,e,f,g=7'b1110000;default:a,b,c,d,e,f,g=7'bx;endcaseendalways (posedge clk_6MHz) begin if(song_on) speaker<=out;else be

11、gin case(in) zero:begin speaker<=0; i<=0; end one:begin /do if(i>=11451) begin speaker=!speaker; i<=0; end else i<=i+1; end two:begin /re if(i>=10204) begin speaker=!speaker; i<=0; end else i<=i+1; end three:begin /mi if(i>=9091) begin speaker=!speaker; i<=0; end else i

12、<=i+1; end four:begin / fa if(i>=8596) begin speaker=!speaker; i<=0; end else i<=i+1; end five:begin /so if(i>=7653) begin speaker=!speaker; i<=0; end else i<=i+1; end six:begin /lo if(i>=6818) begin speaker=!speaker; i<=0; end else i<=i+1; end seven:begin /si if(i>=

13、6073) begin speaker=!speaker; i<=0; end else i<=i+1; end default:begin speaker<=0; i<=0; end endcase end end assign carry=(divider=16383); always (posedge clk_6MHz) begin if(carry) divider<=origin; else divider<=divider+1; end always (posedge carry) begin out<=out; end always (p

14、osedge clk_4Hz) begin case(high,med,low) 'b000000000011: origin<=7281; 'b000000000101: origin<=8730; 'b000000000110: origin<=9565; 'b000000000111: origin<=10310; 'b000000010000: origin<=10647; 'b000000100000: origin<=11272; 'b000000110000: origin<=118

15、31; 'b000001010000: origin<=12556; 'b000001100000: origin<=12974; 'b000100000000: origin<=13516; 'b000000000000: origin<=16383; endcase end always (posedge clk_4Hz) begin if(counter=63) counter<=0; else counter<=counter+1; case(counter) /¼ÇÆ× 0:

16、high,med,low<='b000000000011; 1: high,med,low<='b000000000011; 2: high,med,low<='b000000000011; 3: high,med,low<='b000000000011; 4: high,med,low<='b000000000101; 5: high,med,low<='b000000000101; 6: high,med,low<='b000000000101; 7: high,med,low<=

17、9;b000000000110; 8: high,med,low<='b000000010000; 9: high,med,low<='b000000010000; 10: high,med,low<='b000000010000; 11: high,med,low<='b000000100000; 12: high,med,low<='b000000000110; 13: high,med,low<='b000000010000; 14: high,med,low<='b000000000101

18、; 15: high,med,low<='b000000000101; 16: high,med,low<='b000001010000; 17: high,med,low<='b000001010000; 18: high,med,low<='b000001010000; 19: high,med,low<='b000100000000; 20: high,med,low<='b000001100000; 21: high,med,low<='b000001010000; 22: high,me

19、d,low<='b000000110000; 23: high,med,low<='b000001010000; 24: high,med,low<='b000000100000; 25: high,med,low<='b000000100000; 26: high,med,low<='b000000100000; 27: high,med,low<='b000000100000; 28: high,med,low<='b000000100000; 29: high,med,low<=

20、9;b000000100000; 30: high,med,low<='b000000100000; 31: high,med,low<='b000000100000; 32: high,med,low<='b000000100000; 33: high,med,low<='b000000100000; 34: high,med,low<='b000000100000; 35: high,med,low<='b000000110000; 36: high,med,low<='b0000000001

21、11; 37: high,med,low<='b000000000111; 38: high,med,low<='b000000000110; 39: high,med,low<='b000000000110; 40: high,med,low<='b000000000101; 41: high,med,low<='b000000000101; 42: high,med,low<='b000000000101; 43: high,med,low<='b000000000110; 44: high,med,low<='b000000010000; 45: high,med,low<='b000000010000; 46: high,med,low<='b000000100000; 47: high,med,low<='b000000100000; 48: high,