请问一下这个代码产生的正弦波的频率是怎么算出来的

#include <STC8.H>
#include "intrins.h"
#define uchar unsigned char
#define uint unsigned int
uchar code sintab[160]={
0xFF,0X17,0XFF,
0X17,0XFF,0X3B,0XFE,0XF3,0XFF,0X5F,
0XFE,0XCF,0XFF,0X80,0XFE,0XAE,0XFF,
0X9F,0XFE,0X8F,0XFF,0XBB,0XFE,0X73,
0XFF,0XD3,0XFE,0X5B,0XFF,0XE6,0XFE,
0X48,0XFF,0XF4,0XFE,0X3A,0XFF,0XFC,
0XFE,0X32,0XFF,0XFF,0XFE,0X2F,0XFF,
0XFC,0XFE,0X32,0XFF,0XF4,0XFE,0X3A,
0XFF,0XE6,0XFE,0X48,0XFF,0XD3,0XFE,
0X5B,0XFF,0XBB,0XFE,0X73,0XFF,0X9F,
0XFE,0X8F,0XFF,0X80,0XFE,0XAE,0XFF,
0X5F,0XFE,0XCF,0XFF,0X3B,0XFE,0XF3,
0XFF,0X17,0XFF,0X17,0XFE,0XF3,0XFF,
0X3B,0XFE,0XCF,0XFF,0X5F,0XFE,0XAE,
0XFF,0X80,0XFE,0X8F,0XFF,0X9F,0XFE,
0X73,0XFF,0XBB,0XFE,0X5B,0XFF,0XD3,
0XFE,0X48,0XFF,0XE6,0XFE,0X3A,0XFF,
0XF4,0XFE,0X32,0XFF,0XFC,0XFE,0X2F,
0XFF,0XFF,0XFE,0X32,0XFF,0XFC,0XFE,
0X3A,0XFF,0XF4,0XFE,0X48,0XFF,0XE6,
0XFE,0X5B,0XFF,0XD3,0XFE,0X73,0XFF,
0XBB,0XFE,0X8F,0XFF,0X9F,0XFE,0XAE,
0XFF,0X80,0XFE,0XCF,0XFF,0X5F,0XFE,
0XF3,0XFF,0X3B


}  ;


main()
{
P1M0=0x00;
P1M1=0x00;
TMOD=0X11;
AUXR &=0X7F;
ET1=1;
ET0=1;
TR0=1;
TR1=0;
EA=1;
while(1);

}

Timer0() interrupt 1
{
TR0=0;
P16=1;
TR1=1;
}
Timer1() interrupt 3
{
uchar aa,bb;
P16=0;
aa=bb*4;
TR1=0;
TH0=sintab[aa];
TL0=sintab[aa+1];
TH1=sintab[aa+2];
TL1=sintab[aa+3];
bb++;
if(bb>39)bb=0;
TR0=1;
}

y=A*sin(2*π*f*t)
y:纵坐标数值
A：波幅
f：频率
t：采样时刻
(2*π*f*t)算出来的单位是 弧度 (RAD)

1.这个程序相当于把sin函数用pwm输出，所以time0+time1是一个采样周期，大约1D0~1D1。time0是高电位，time1是低。要算每个取值周期，time0和time1的比值，再乘以刚才的周期取整，就是你sintab[]的值。
2.time0和time1的比值,就是每个取样周期，函数的定积分跟取样周期面积剩余的比值。
3.所以可以很明显看出你的数组前21组（4个一组），相当于余弦函数0~180度；后19组相当于正弦函数0~180度。后一个函数比前一个大，频率也快。

xuyaqi 发表于 2021-9-26 14:51
y=A*sin(2*π*f*t)
y:纵坐标数值
A：波幅

这个我知道啊我想说的是程序里面是怎样体现的

glinfei 发表于 2021-9-26 16:17
1.这个程序相当于把sin函数用pwm输出，所以time0+time1是一个采样周期，大约1D0~1D1。time0是高电位，time1 ...

那我想要把频率改为1k怎么改大佬

seanhhp 发表于 2021-9-26 17:21
那我想要把频率改为1k怎么改大佬

可能我上面写的不够清楚，不过我是文科生啊。你目前AUXR设置成12T了，假如是12Mhz,你的两个终端计数合计1D1，采样输出频率都2K了，你的数组一共40组，大约以50Hz的频率输出。你说的频率改为1k，是指采样/输出频率还是函数的频率，还是1s输出函数1k个呢？如果只动采样输出频率，不用算积分，只要按比例调整数组，注意是用0xFFFF-（一对数组）的值；函数变了你重算，不过这种定积分，用excel拉表算就行了。