【轉(zhuǎn)】單片機SPI接口和AD7799通信程序

ZLM_圖書館 2014-07-04

展開全文

sbit AD7799_CS=P1^4;
sbit AD7799_RDY=P1^6;

//SPCR SPI控制寄存器

//SPSR SPI狀態(tài)寄存器

//SPDAT    SPI數(shù)據(jù)寄存器
void SPI_init(void)
{
    SPCR=0x5e;//SPI控制寄存器，中斷禁止，SPI使能，高位在前，主機模式，時鐘空閑時為高，后沿觸發(fā)移位，時鐘分頻64
SPSR=0x00;//清中斷標志位
}
/*--------------------------------------------
寫AD7799寄存器函數(shù)
WriteData：要寫的數(shù)據(jù)
----------------------------------------------*/
void WriteByteToAd7799(unsigned char WriteData)
{
    SPDAT= WriteData;
    while(~SPSR&0x80);        //等待數(shù)據(jù)發(fā)送完
    SPSR=0x00;                     //清中斷標志位

}
/*--------------------------------------------
防止時序混亂，實現(xiàn)再同步
----------------------------------------------*/
void WaiteRDY(void)
{
    unsigned int count=0 ;
    while(AD7799_RDY)
    {
        count++;
        if(count>20000)
        {
             //reset ad7799
            WriteByteToAd7799(0xff);

            WriteByteToAd7799(0xff);
                                      /*----------防止時序混亂，重新同步----------*/
            WriteByteToAd7799(0xff);

WriteByteToAd7799(0xff);

            AD7799_init();
            break ;
        }
    }
}

/*--------------------------------------------
AD7799初始化函數(shù)
----------------------------------------------*/
void AD7799_init(void)
{
AD7799_CS=0;
/*------------------------增益為128,通道0----------------------------------------*/
WriteByteToAd7799(0x10); //寫通信寄存器設(shè)置下一個操作為寫配置寄存器

WriteByteToAd7799(0x37); //增益為128

WriteByteToAd7799(0x30); //通道0

/*------------------- 寫模式寄存器初始化零值校準------------------------------------*/
WriteByteToAd7799(0x08); //寫通信寄存器設(shè)置下一個操作為寫模式寄存器

WriteByteToAd7799(0x80);

WriteByteToAd7799(0x0A);

WaiteRDY(); //Wait for RDY pin to go low to indicate end of calibration cycle*/
/*------------------寫模式寄存器初始化全值校準-------------------------------------*/
WriteByteToAd7799(0x08); //寫通信寄存器設(shè)置下一個操作為寫模式寄存器

WriteByteToAd7799(0xA0);

WriteByteToAd7799(0x0A);

WaiteRDY(); // Wait for RDY pin to go low to indicate end of calibration cycle
/*------------------模式0,Continuous-Conversion Mode,Fadc=16.7HZ------------------*/
WriteByteToAd7799(0x08); //寫通信寄存器設(shè)置下一個操作為寫模式寄存器

WriteByteToAd7799(0x00);

WriteByteToAd7799(0x0A);

}
unsigned long ReadAd7799ConversionData(void)
{
    unsigned long ConverData;
    unsigned char ADSAT ;
    unsigned char ErrNUM=0;
    WaiteRDY();

WriteByteToAd7799(0x40); //寫通信寄存器設(shè)置下一個操作為讀狀態(tài)STATUS寄存器

WriteByteToAd7799(0xff); //偽寫通信寄存器，為讀狀態(tài)寄存器提供時鐘

    ADSAT=SPDAT;                 //讀取接收到的數(shù)據(jù)
    while((ADSAT&0x40)||(!(ADSAT&0x08)))      //出錯或者讀寫異常
    {
         //reset ad7799
         WriteByteToAd7799(0xff);

         WriteByteToAd7799(0xff);
                                      /*----------防止時序混亂，重新同步----------*/
         WriteByteToAd7799(0xff);

WriteByteToAd7799(0xff);

//-------------------------------------------------------------------------------------
        AD7799_init();

        WaiteRDY();
        WriteByteToAd7799(0x40);     //寫通信寄存器設(shè)置下一個操作為讀狀態(tài)STATUS寄存器

WriteByteToAd7799(0xff); //偽寫通信寄存器，為讀狀態(tài)寄存器提供時鐘

        ADSAT=SPDAT;                 //讀取接收到的數(shù)據(jù)

        ErrNUM++;
        if(ErrNUM>5)break;
    }

WriteByteToAd7799(0x58); //寫通信寄存器設(shè)置下一個操作為連續(xù)讀數(shù)據(jù)寄存器

    WaiteRDY();
    /* Wait for RDY pin to go low to indicate end of calibration cycle*/
    if(!AD7799_RDY)
    {
        ConverData=0 ;
/*-----------------Read Conversion Result from AD7799's Data Register----------------*/

        WriteByteToAd7799(0xff);             //偽寫通信寄存器，為讀數(shù)據(jù)寄存器寄存器提供時鐘
        ConverData=SPDAT;
        ConverData=ConverData<<8 ;

        WriteByteToAd7799(0xff);             //偽寫通信寄存器，為讀數(shù)據(jù)寄存器寄存器提供時鐘
        ConverData=ConverData+SPDAT;
        ConverData=ConverData<<8 ;

        WriteByteToAd7799(0xff);             //偽寫通信寄存器，為讀數(shù)據(jù)寄存器寄存器提供時鐘
        ConverData=ConverData+SPDAT;

    }
    if(ErrNUM>5)return(0);
    else return(ConverData);
}