方案是一个FM收音机，包含完整的原理图和源代码，拿回家马上就可以动手去做。该收音机基于STC89C52RC（STC89C52RC数据手册）单片机和TEA5767芯片设计，同时使用飞利浦的TDA1308音频功放IC，可以使用耳机收听，也可以接功放收听，音质不错，在实验室可以接受到十几个清晰的电台。主板也是一个很好的51单片机学习板，单片机的所有IO口已经在电路板上引出，方便实验。
单片机源程序如下:
- #include <reg51.h>
- #include <string.h>
- #include <math.h>
- #include <uart.h>
- #include <i2c.h>
- #define max_freq 108000
- #define min_freq 87500
- sbit KEY1=P3^2;
- sbit KEY2=P3^3;
- unsigned char radio_write_data[5]={0x29,0xc2,0x20,0x11,0x00}; //要写入TEA5767的数据
- //unsigned char radio_write_data[5]={0x2a,0xb6,0x40,0x11,0x40}; //要写入TEA5767的数据
- unsigned char radio_read_data[5]; //TEA5767读出的状态
- unsigned int default_pll=0x301d; //0x29f9; //默认存台的pll,95.8MHz
- //unsigned int max_pll=0x339b; //108MHz时的pll,
- //unsigned int min_pll=9000; //70MHz时的pll
- unsigned long frequency;
- unsigned int pll;
- /*void delay(unsigned int time)
- {
- while(time--);
- }*/
- void delay1ms (unsigned int b)//1ms
- {
- for(b;b>0;b--)
- {unsigned int i;
- for(i=0;i<300;i++)
- {;}
- }
- }
- void radio_write(void)
- {
- unsigned char i;
- iic_start();
- iic_write8bit(0xc0); //TEA5767写地址
- if(!iic_testack())
- {
- for(i=0;i<5;i++)
- {
- iic_write8bit(radio_write_data[i]);
- iic_ack();
- }
- }
- iic_stop();
- }
- //由频率计算PLL
- void get_pll(void)
- {
- unsigned char hlsi;
- // unsigned int twpll=0;
- hlsi=radio_write_data[2]&0x10; //HLSI位
- if (hlsi)
- pll=(unsigned int)((float)((frequency+225)*4)/(float)32.768); //频率单位:k
- else
- pll=(unsigned int)((float)((frequency-225)*4)/(float)32.768); //频率单位:k
- }
- //由PLL计算频率
- void get_frequency(void)
- {
- unsigned char hlsi;
- unsigned int npll=0;
- npll=pll;
- hlsi=radio_write_data[2]&0x10;
- if (hlsi)
- frequency=(unsigned long)((float)(npll)*(float)8.192-225); //频率单位:KHz
- else
- frequency=(unsigned long)((float)(npll)*(float)8.192+225); //频率单位:KHz
- }
- //读TEA5767状态,并转换成频率
- void radio_read(void)
- {
- unsigned char i;
- unsigned char temp_l,temp_h;
- pll=0;
- iic_start();
- iic_write8bit(0xc1); //TEA5767读地址
- if(!iic_testack())
- {
- for(i=0;i<5;i++)
- {
- radio_read_data[i]=iic_read8bit();
- iic_ack();
- }
- }
- iic_stop();
- temp_l=radio_read_data[1];
- temp_h=radio_read_data[0];
- temp_h&=0x3f;
- pll=temp_h*256+temp_l;
- get_frequency();
- }
- //手动设置频率,mode=1,+0.1MHz; mode=0:-0.1MHz ,不用考虑TEA5767用于搜台的相关位:SM,SUD
- void search(bit mode)
- {
- radio_read();
- if(mode)
- {
- frequency+=10;
- if(frequency>max_freq)
- frequency=min_freq;
- }
- else
- {
- frequency-=10;
- if(frequency<min_freq)
- frequency=max_freq;
- }
- get_pll();
- radio_write_data[0]=pll/256;
- radio_write_data[1]=pll%256;
- radio_write_data[2]=0x20;
- radio_write_data[3]=0x11;
- radio_write_data[4]=0x00;
- radio_write();
- }
- //自动搜台,mode=1,频率增加搜台; mode=0:频率减小搜台,不过这个好像不能循环搜台
- /*void auto_search(bit mode)
- {
- radio_read();
- get_pll();
- if(mode)
- radio_write_data[2]=0xa0;
- else
- radio_write_data[2]=0x20;
- radio_write_data[0]=pll/256+0x40;
- radio_write_data[1]=pll%256;
- radio_write_data[3]=0x11;
- radio_write_data[4]=0x00;
- radio_write();
- radio_read();
- while(!(radio_read_data[0]&0x80)) //搜台成功标志
- {
- delay(1000);
- radio_read();
- //disp_freq(9,1);
- PutNum(frequency);
- }
- } */
- void main()
- {
- UART_Init();//串口初始化
- UART_Send_Str("调频收音机\n");
- radio_write();
- while(1)
- {
- if(KEY1==0)
- {
- delay1ms(15); //延时15ms
- if(KEY1==0)
- while(KEY1==0);//等待按键释放
- search(1);
- radio_read();
- UART_Send_Str("目前频率\n");
- UART_Put_Num(frequency);
- UART_Send_Str("\n");
- }
- if(KEY2==0)
- {
- delay1ms(15); //延时15ms
- if(KEY2==0)
- while(KEY2==0);//等待按键释放
- search(0);
- radio_read();
- UART_Send_Str("目前频率\n");
- UART_Put_Num(frequency);
- UART_Send_Str("\n");
- }
- }
- }
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