基于51单片机的dds信号发生器

要实现基于51单片机的DDS信号发生器，需要一些硬件和软件资源。

硬件资源：

1. 51单片机

2. AD9850芯片

3. LCD1602液晶显示屏

4. 其他相关电子器件

软件资源：

1. Keil C51编译器

2. 相关的C语言库函数

下面是一个基于51单片机的DDS信号发生器的示例代码：

#include <reg51.h>

#define FREQ0 1000.0    //默认输出频率为1kHz
#define FREQ1 125000.0  //AD9850的参考频率为125MHz

unsigned long int frequency;  //用于存储输出频率
unsigned char phase;          //用于存储输出相位

void delay(unsigned int t)  //简单的延时函数
{
    unsigned int i, j;
    for (i = 0; i < t; i++)
        for (j = 0; j < 125; j++);
}

void write_ad9850(unsigned char data)  //向AD9850写入8位数据
{
    unsigned char i;
    for (i = 0; i < 8; i++)
    {
        if (data & 0x80)
            P2 |= 0x02;
        else
            P2 &= ~0x02;
        P2 |= 0x04;
        P2 &= ~0x04;
        data <<= 1;
    }
}

void set_frequency(unsigned long int freq)  //设置输出频率
{
    unsigned long int delta;
    unsigned char i;

    delta = freq / FREQ1 * 4294967296.0;
    write_ad9850(0x20);
    write_ad9850(delta >> 24);
    write_ad9850(delta >> 16);
    write_ad9850(delta >> 8);
    write_ad9850(delta);
    write_ad9850(0x0);
    write_ad9850(0x0);
    write_ad9850(0x0);
    write_ad9850(0x0);
    P2 &= ~0x08;
    P2 |= 0x08;
}

void set_phase(unsigned char ph)  //设置输出相位
{
    unsigned char i;
    ph = ph % 360;
    ph = ph / 1.41;
    write_ad9850(0xC0);
    write_ad9850(ph);
    write_ad9850(0x0);
    write_ad9850(0x0);
    write_ad9850(0x0);
}

void lcd_init()  //初始化LCD1602液晶显示屏
{
    delay(15);
    P0 = 0x30;
    P2 &= ~0x01;
    delay(5);
    P2 |= 0x01;
    delay(5);
    P0 = 0x30;
    P2 &= ~0x01;
    delay(5);
    P2 |= 0x01;
    delay(5);
    P0 = 0x30;
    P2 &= ~0x01;
    delay(5);
    P2 |= 0x01;
    delay(5);
    P0 = 0x38;
    P2 &= ~0x01;
    delay(5);
    P2 |= 0x01;
    delay(5);
    P0 = 0x08;
    P2 &= ~0x01;
    delay(5);
    P2 |= 0x01;
    delay(5);
    P0 = 0x01;
    P2 &= ~0x01;
    delay(5);
    P2 |= 0x01;
    delay(5);
    P0 = 0x06;
    P2 &= ~0x01;
    delay(5);
    P2 |= 0x01;
    delay(5);
    P0 = 0x0C;
    P2 &= ~0x01;
    delay(5);
    P2 |= 0x01;
    delay(5);
}

void lcd_display(unsigned char row, unsigned char column, unsigned char *str)  //在LCD1602液晶显示屏上显示字符串
{
    unsigned char i;
    if (row)
        column |= 0x40;
    column |= 0x80;
    P0 = column;
    P2 &= ~0x01;
    delay(5);
    P2 |= 0x01;
    delay(5);
    for (i = 0; str[i]; i++)
    {
        P0 = str[i];
        P2 |= 0x04;
        P2 &= ~0x04;
        delay(5);
    }
}

void main()
{
    unsigned char buf[16];
    frequency = FREQ0;
    phase = 0;
    lcd_init();
    set_frequency(frequency);
    set_phase(phase);
    while (1)
    {
        sprintf(buf, "Freq:%dHz", frequency);
        lcd_display(0, 0, buf);
        sprintf(buf, "Phase:%d", phase);
        lcd_display(1, 0, buf);
        delay(200);
    }
}

这个示例代码使用了AD9850芯片来生成DDS信号，并通过LCD1602液晶显示屏显示当前的输出频率和输出相位。在代码中还实现了设置输出频率和相位的函数，并通过按键等外部输入来修改这些参数。你可以根据自己的需求进行修改和扩展。