ad7705.txt

AD7705的C语言程序

                       
                        #include<reg51.h>
                        #include<absacc.h>
                        #include<intrins.h>
                        #include<math.h>

                        sbit D_DAT=P1^0; 
                        //这一段是用来指定数显的，我用的是周立功dp-51开发机,该开发机有4个数码管 
                        sbit D_CLK=P1^1;
                        sbit DISPB0=P1^7;
                        sbit DISPB1=P1^6;
                        sbit DISPB2=P1^5;
                        sbit DISPB3=P1^4;
                        sbit DISPB4=P1^3;

                        sbit ADC_DIN=P3^0; //这一段是指定ad7705的信号引脚
                        sbit ADC_CLK=P3^1; //指定时钟引脚
                        sbit ADC_DRDY=P3^2; //指定转换标志位

                        float voltage; //这个全局变量是用来给数显子程序传递采样到的数据的

                        unsigned char data display_buffer[5]; //显示缓冲

                        unsigned char code led[17]= //显示段码表
         {0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90,0x88,0x83,0xC6,0xA1,0x86,0x8E,0xFF};


                        /*****************************************/
                        void send(unsigned char a) //通过P1口给数显发送8位数据
                        {
                        unsigned char i;
                        for(i=0;i<8;i++)
                        {
                        if(_crol_(a,i)&0x80)
                        D_DAT=1;
                        else
                        D_DAT=0;
                        D_CLK=0;
                        D_CLK=1;
                        }
                        }
                        /*****************************************/
                        void DISP_DLEAY(void) //显示延迟子程序
                        {
                        unsigned char i,j;
                        for(i=0;i<10;i++)
                        for(j=0;j<5;j++);
                        }
                        /*****************************************/
                        void disp(void) //给数码管发显示缓冲区的段码
                        {
                        unsigned char a;
                        a=0xff;
                        send(a);
                        DISPB0=0;
                        DISP_DLEAY();
                        DISPB0=1;

                        a=led[display_buffer[1]];
                        send(a);
                        DISPB1=0;
                        DISP_DLEAY();
                        DISPB1=1;

                        a=led[display_buffer[2]];
                        send(a);
                        DISPB2=0;
                        DISP_DLEAY();
                        DISPB2=1;

                        a=led[display_buffer[3]];
                        send(a);
                        DISPB3=0;
                        DISP_DLEAY();
                        DISPB3=1;

                        a=led[display_buffer[4]];
                        send(a);
                        DISPB4=0;
                        DISP_DLEAY();
                        DISPB4=1; 
                        }

                        /*****************************************/

                        void display() /*将数据转换成相应的段码，
                        并给显示缓冲区赋段码*/
                        {

                        float y,z,x; 

                        x=voltage;
                        x=x/10.0;
                        y=modf(x,&z);
                        display_buffer[1]=(unsigned char)z;

                        x=10.0*y;
                        y=modf(x,&z);
                        display_buffer[2]=(unsigned char)z;

                        x=10.0*y;
                        y=modf(x,&z);
                        display_buffer[3]=(unsigned char)z;

                        x=10.0*y;
                        y=modf(x,&z);
                        display_buffer[4]=(unsigned char)z;


                        disp();
                        disp();
                        disp();
                        disp();
                        disp();
                        }

                        /****************************************************************/

                        unsigned char rearrange(unsigned char a) 
                        /*将8位数据a的顺序颠倒后赋给b。
                        因为串口发送顺序和ad7705的接收顺序刚好相反*/
                        {
                        unsigned char i,b;
                        b=a&0x01;
                        for(i=1; i<8; i++)
                        {
                        b=b<<1;
                        a=a>>1;
                        b=b+(a&0x01);
                        }
                        return(b);
                        }

                        /****************************************************************/

                        void WriteToReg_ADC(unsigned char a) //通过串口给ad7705发送命令字a
                        {

                        SCON=0;

                        TI=0;
                        SBUF=a;
                        while(!TI);

                        }

                        /*************************************************************/

                        void MX7705_Init() //ad7705初始化
                        {
                        unsigned char i; 

                        ADC_CLK=1; //防止接口迷失
                        ADC_DIN=1;
                        for(i=0;i<100;i++)//prevent interface from losting
                        {
                        ADC_CLK=0;
                        ADC_CLK=1;
                        } 

                        WriteToReg_ADC(0x04); //write 0x20 to communication 
                        register to choose channel 0 
                        //and clock register for the next one to write

                        WriteToReg_ADC(0x20); 
                        //写0x04到时钟寄存器，指定晶振频率为2.4576MHz,采样率为50Hz.
                        WriteToReg_ADC(0x08); //write 0x10 to communication 
                        register to choose channel 0
                        //and setup register for the next one to write

                        WriteToReg_ADC(0x22); //写0x44到设置寄存器，指定增益为1, buffer off, 
                        FSYNC=0, and self-calibration 

                        }

                        /*************************************************************/

                        unsigned int ReadWord()
                        {
                        unsigned char high8,low8;
                        unsigned int out;

                        SCON=0;

                        REN=1; //allow serial port to recieve data
                        RI=0;
                        while(!RI); //waiting the end of recieve of 8 bit
                        high8=SBUF;

                        ADC_CLK=1;

                        RI=0;
                        while(!RI);
                        low8=SBUF;
                        REN=0; 
                        out=rearrange(high8);
                        out=out<<8;
                        out=out+rearrange(low8);
                        return(out);

                        }
                        /*************************************************************/


                        /*************************************************************/

                        main()
                        {
                        unsigned int data_out;


                        MX7705_Init();

                        while(ADC_DRDY==0)
                        {

                        WriteToReg_ADC(0x1C); //给通讯寄存器发0x38，指定下一个读数据寄存器
                        data_out=ReadWord(); //从数据寄存器中读16位数据
                        voltage=5.0*(data_out/65536.0); //将所读数据转换为电压值
                        display(); 

                        }

                        }