你的问题很好解释啊！
256个点，DAC0832速率为1us左右，理论上频率可以达到1M/256=3906HZ。
但实际上受器件影响，不一定达到这么高的频率。
不过由于你用的是51单片机，12T的模式，执行指令的速率非常低，所以真正影响频率的首先不是DAC0832，而是单片机。因相对于DAC0832的速率，单片机的速率慢了很多，所以单片机的速率是跟不上DAC0832的。
像你程序中用了这么多if，各种判断，频率的运算，还要加上中断的耗时，必定会将频率降下来了。
12T模式的51，单周期时间为1M，加上这些if啊，运算啊，中断耗时啊，频率一下子就降下来了……
所以，要提高速度，取的波形点降低，没必要高这么多，256太高了。你DAC0832后级做出滤波即可。采样定理不是说了嘛，采样速率只要不小于2倍的信号频率，即可还原出原始波形。理论上波形点只要2点就够了…… 但实际应用中，取16个点，或者32个点，也是足够了…… 拿32个点来说，256/32=8，速度一下子就上升8倍……
51是不可能产生正弦波的，你可以用个高速的DA把正弦波的数组依次送出就能得到正弦波，最好再虑下波就能得到更稳定的正弦波。或者输出方波把基波滤出来也行的
基于单片机的的信号发生器大概有两种形式，1、全部波形信号由单片机软件产生，再经由D/A转换输出；
2、单片机+专用信号发生系芯片，这种方式单片机仅扮演主控角色，信号由芯片硬件产生；
把满幅的DA波形表做出来，根据频率算好间隔送DA输出就是100%幅度的波形，输出时乘以0-1之间的系数就是调幅后的波形了。如果单片机速度足够快，可以实时计算波形数据输出，不用做波形表。
#includereg51.h
#includeabsacc.h
#includeMAX72191.h
#defineDAC XBYTE[0x7fff] //P2.7接CS
sbitkey0 = P3^2;// 增减切换键
sbitkey1 = P3^3;//个位,十位，百位，千位的控制切换
sbitkey2 = P3^4;// 调整位
sbitkey3 = P3^5;// 波形选择正弦、三角、矩形波，锯齿波
unsignedchar i,j;
unsignedint counter,step,flag;
typedefunsigned int uint;
//定时器0初始化
voidInit_Timer0(void)
{
TMOD = (TMOD 0XF0) | 0X01;//设置工作方式和定时初始值
TH0 = 0xff;
TL0 = 0x00;
TR0 =1; //启动定时器
ET0 =1;
}
//定义输出波形的代码
unsignedchar code type[4][256]={
{ //正弦波代码
0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x1, 0x1, 0x2, 0x3, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8,
0x9, 0xb,0xc, 0xd, 0xf, 0x10,0x12,0x13,0x15,0x17,0x19,0x1b,0x1d,0x1f,0x21,0x23,
0x25,0x27,0x2a,0x2c,0x2e,0x31,0x33,0x36,0x39,0x3b,0x3e,0x41,0x43,0x46,0x49,0x4c,
0x4f,0x52,0x55,0x58,0x5b,0x5e,0x61,0x64,0x67,0x6a,0x6d,0x70,0x73,0x76,0x7a,0x7d,
0x80,0x83,0x86,0x89,0x8c,0x8f,0x93,0x96,0x99,0x9c,0x9f,0xa2,0xa5,0xa8,0xab,0xae,
0xb1,0xb4,0xb6,0xb9,0xbc,0xbf,0xc1,0xc4,0xc7,0xc9,0xcc,0xce,0xd1,0xd3,0xd5,0xd8,
0xda,0xdc,0xde,0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xeb,0xed,0xef,0xf0,0xf1,0xf3,0xf4,
0xf5,0xf6,0xf8,0xf9,0xf9,0xfa,0xfb,0xfc,0xfc,0xfd,0xfd,0xfe,0xfe,0xfe,0xfe,0xfe,
0xfe,0xfe,0xfe,0xfe,0xfe,0xfd,0xfd,0xfc,0xfc,0xfb,0xfa,0xf9,0xf9,0xf8,0xf6,0xf5,
0xf4,0xf3,0xf1,0xf0,0xef,0xed,0xeb,0xea,0xe8,0xe6,0xe4,0xe2,0xe0,0xde,0xdc,0xda,
0xd8,0xd5,0xd3,0xd1,0xce,0xcc,0xc9,0xc7,0xc4,0xc1,0xbf,0xbc,0xb9,0xb6,0xb4,0xb1,
0xae,0xab,0xa8,0xa5,0xa2,0x9f,0x9c,0x99,0x96,0x93,0x8f,0x8c,0x89,0x86,0x83,0x80,
0x7d,0x7a,0x76,0x73,0x70,0x6d,0x6a,0x67,0x64,0x61,0x5e,0x5b,0x58,0x55,0x52,0x4f,
0x4c,0x49,0x46,0x43,0x41,0x3e,0x3b,0x39,0x36,0x33,0x31,0x2e,0x2c,0x2a,0x27,0x25,
0x23,0x21,0x1f,0x1d,0x1b,0x19,0x17,0x15,0x13,0x12,0x10,0xf,0xd, 0xc, 0xb, 0x9,
0x8,0x7, 0x6, 0x5, 0x4, 0x3, 0x3, 0x2, 0x1, 0x1, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
},
{ //三角波代码
0x2,0x4, 0x6, 0x8, 0xa, 0xc, 0xe, 0x10,0x12,0x14, 0x16, 0x18, 0x1a,0x1c, 0x1e, 0x20,
0x22,0x24, 0x26, 0x28, 0x2a, 0x2c, 0x2e, 0x30,0x32, 0x34, 0x36, 0x38, 0x3a, 0x3c, 0x3e, 0x40,
0x42,0x44, 0x46, 0x48, 0x4a, 0x4c, 0x4e, 0x50,0x52, 0x54, 0x56, 0x58, 0x5a, 0x5c, 0x5e, 0x60,
0x62,0x64, 0x66, 0x68, 0x6a, 0x6c, 0x6e, 0x70,0x72, 0x74, 0x76, 0x78, 0x7a, 0x7c, 0x7e, 0x80,
0x82,0x84, 0x86, 0x88, 0x8a, 0x8c, 0x8e, 0x90,0x92, 0x94, 0x96, 0x98, 0x9a, 0x9c, 0x9e, 0xa0,
0xa2,0xa4, 0xa6, 0xa8, 0xaa, 0xac, 0xae, 0xb0,0xb2, 0xb4, 0xb6, 0xb8, 0xba, 0xbc,0xbe, 0xc0,
0xc2,0xc4, 0xc6, 0xc8, 0xca, 0xcc, 0xce, 0xd0,0xd2, 0xd4, 0xd6, 0xd8, 0xda, 0xdc,0xde, 0xe0,
0xe2,0xe4, 0xe6, 0xe8, 0xea, 0xec, 0xee, 0xf0,0xf2, 0xf4, 0xf6, 0xf8, 0xfa, 0xfc,0xfe, 0xff,
0xfe,0xfc, 0xfa, 0xf8, 0xf6, 0xf4, 0xf2, 0xf0,0xee, 0xec, 0xea, 0xe8, 0xe6, 0xe4,0xe2, 0xe0,
0xde,0xdc, 0xda, 0xd8, 0xd6, 0xd4, 0xd2, 0xd0,0xce, 0xcc, 0xca, 0xc8, 0xc6, 0xc4,0xc2, 0xc0,
0xbe,0xbc, 0xba, 0xb8, 0xb6, 0xb4, 0xb2, 0xb0,0xae, 0xac, 0xaa, 0xa8, 0xa6, 0xa4,0xa2, 0xa0,
0x9e, 0x9c, 0x9a, 0x98, 0x96, 0x94, 0x92, 0x90,0x8e, 0x8c, 0x8a, 0x88, 0x86, 0x84, 0x82, 0x80,
0x7e, 0x7c, 0x7a, 0x78, 0x76, 0x74, 0x72, 0x70,0x6e, 0x6c, 0x6a, 0x68, 0x66, 0x64, 0x62, 0x60,
0x5e, 0x5c, 0x5a, 0x58, 0x56, 0x54, 0x52, 0x50,0x4e, 0x4c, 0x4a, 0x48, 0x46, 0x44, 0x42, 0x40,
0x3e, 0x3c, 0x3a, 0x38, 0x36, 0x34, 0x32, 0x30,0x2e, 0x2c, 0x2a, 0x28, 0x26, 0x24, 0x22, 0x20,
0x1e, 0x1c, 0x1a, 0x18, 0x16, 0x14, 0x12, 0x10,0xe, 0xc, 0xa, 0x8, 0x6, 0x4, 0x2, 0x00
},
{// 矩形脉冲波代码
0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,
0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,
0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,
0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,
0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,
0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,
0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,
0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,
0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,
0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,
0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,
0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,
0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,
0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,
0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,
0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,
},
{//锯齿波代码
0x00,0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,0x08,0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x10,0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,0x18,0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
0x20,0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,0x28,0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
0x30,0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,0x38,0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
0x40,0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,0x48,0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
0x50,0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,0x58,0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
0x60,0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,0x68,0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
0x70,0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,0x78,0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
0x80,0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,0x88,0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
0x90,0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,0x98,0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
0xa0,0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,0xa8,0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
0xb0,0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,0xb8,0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
0xc0,0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,0xc8,0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
0xd0,0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,0xd8,0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
0xe0,0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,0xe8,0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
0xf0,0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,0xf8,0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff}
};
//显示子函数
Disp7219(unsignedlong dat)
{
unsigned char i;
unsigned char led[8];
led[7]=dat%10;
led[6]=dat/10%10;
led[5]=dat/100%10;
led[4]=dat/1000%10;
led[3]=dat/10000%10;
led[2]=dat/100000%10;
led[1]=dat/1000000%10;
led[0]=dat/10000000%10;
for(i=0;i8;i++)
{
max_7219(i+1, led[i]);
}
}
//延时约1m秒
voiddelay_ms(uint n)
{
uchar j;
while(n--)
for(j=0;j120;j++);
}
//主函数
main()
{
unsigned int f,n,j;
delay_ms(500);
Init_Max7219();//初始化7219
Disp7219(000);
Init_Timer0();
step=18;
EA = 1;
while(1)
{
if(key0 == 0) n=n+1;
if(n==2)n=0;
if(key1==0) j=j+1;
if(j==4) j=0;
if(n==0 j == 0 key2 == 0) if(step180) step+=18; //个位增
if(n==1 j == 0 key2 == 0) if(step18) step-=18; //个位减
if(n==0 j == 1 key2 == 0) if(step1800) step+=180;//十位增
if(n==1 j == 1 key2 == 0) if(step180) step-=180; //十位减
if(n==0 j == 2 key2 == 0) if(step18000) step+=1800;//百位增
if(n==1 j == 2 key2 == 0) if(step1800) step-=1800;//百位减
if(n==0 j == 3 key2 == 0) if(step54000) step+=18000;//千位增
if(n==1 j == 3 key2 == 0) if(step18000) step-=18000;//千位减
if(key3==0)flag=flag+1;if(flag==4)flag=0;
while((!key0)||(!key1)||(!key2)||(!key3));
f=step/18;
Disp7219(f);}//显示频率
}
// 定时中断服务
voidTimer0(void) interrupt 1 using 2
{
TH0 = 0xff;
TL0 = 0x00;
counter = counter + step;
DAC=type[flag][(unsignedint)counter8];
}
基于51单片机信号发生器的介绍到此就结束了，感谢您耐心阅读，谢谢。
本文标签：基于51单片机信号发生器
