51单片机运用C语言编程，对正弦波的编程的方式使用的是查表发，那 为什么输出频率变化这些表仍能够使用呢？

Question

uchar code tosin[256]={ //正弦波编码
0x80,0x83,0x86,0x89,0x8D,0x90,0x93,0x96,
0x99,0x9C,0x9F,0xA2,0xA5,0xA8,0xAB,0xAE,
0xB1,0xB4,0xB7,0xBA,0xBC,0xBF,0xC2,0xC5,
0xC7,0xCA,0xCC,0xCF,0xD1,0xD4,0xD6,0xD8,
0xDA,0xDD,0xDF,0xE1,0xE3,0xE5,0xE7,0xE9,
0xEA,0xEC,0xEE,0xEF,0xF1,0xF2,0xF4,0xF5,
0xF6,0xF7,0xF8,0xF9,0xFA,0xFB,0xFC,0xFD,
0xFD,0xFE,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFE,0xFD,
0xFD,0xFC,0xFB,0xFA,0xF9,0xF8,0xF7,0xF6,
0xF5,0xF4,0xF2,0xF1,0xEF,0xEE,0xEC,0xEA,
0xE9,0xE7,0xE5,0xE3,0xE1,0xDE,0xDD,0xDA,
0xD8,0xD6,0xD4,0xD1,0xCF,0xCC,0xCA,0xC7,
0xC5,0xC2,0xBF,0xBC,0xBA,0xB7,0xB4,0xB1,
0xAE,0xAB,0xA8,0xA5,0xA2,0x9F,0x9C,0x99,
0x96,0x93,0x90,0x8D,0x89,0x86,0x83,0x80,
0x80,0x7C,0x79,0x78,0x72,0x6F,0x6C,0x69,
0x66,0x63,0x60,0x5D,0x5A,0x57,0x55,0x51,
0x4E,0x4C,0x48,0x45,0x43,0x40,0x3D,0x3A,
0x38,0x35,0x33,0x30,0x2E,0x2B,0x29,0x27,
0x25,0x22,0x20,0x1E,0x1C,0x1A,0x18,0x16,
0x15,0x13,0x11,0x10,0x0E,0x0D,0x0B,0x0A,
0x09,0x08,0x07,0x06,0x05,0x04,0x03,0x02,
0x02,0x01,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x02,
0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,
0x0A,0x0B,0x0D,0x0E,0x10,0x11,0x13,0x15,
0x16,0x18,0x1A,0x1C,0x1E,0x20,0x22,0x25,
0x27,0x29,0x2B,0x2E,0x30,0x33,0x35,0x38,
0x3A,0x3D,0x40,0x43,0x45,0x48,0x4C,0x4E,
0x51,0x55,0x57,0x5A,0x5D,0x60,0x63,0x66,
0x69,0x6C,0x6F,0x72,0x76,0x79,0x7C,0x80
};

if(P1_0==0&&P1_1==0) //正弦
{
s1++;
ss1=tosin[s1];
P0=ss1;
tp=0;
}

Answer 1

我来告诉你吧。如果你查表执行的速度快，那么这个正弦波（基波）的频率就高；如果你查表的速度慢，那么这个基波的频率就低。查表速度一般通过定时器来控制，需要比较的稳定才行。

追问

那表内的内容的编排是否有一定的规律可循？
是否是利用了人眼的视觉暂留？本身表内的都是一些点，如果速度极慢，看到的是不连贯的，但是速度较快看到的是连贯的……是这个意思吗？

Answer 2

查表直接把值送给了P0口了，P0口接的DA转换器吗？（如果是AT89S51注意接上拉电阻）
如果是DA,你这里直接把数值送给了P0口，DA转换的速度跟的上吗，建议DELAY一下！

Answer 3

神马东东

Answer 4

我来学习一下