MSP430杂谈--AD7793硬件SPI驱动与模拟SPI驱动

最近项目中用到了AD7793读取铂电阻值来得到相应的温度，编写了基于MSP430的硬件驱动程序和模拟驱动程序，并且能成功运行，现在记录一下分享给大家。

AD7793硬件IIC驱动完整版下载链接：https://download.csdn.net/download/qq_42580947/11041933

AD7793模拟IIC驱动完整版下载链接：https://download.csdn.net/download/qq_42580947/11041961

PS：目前资源积分无法自行调整，有谁知道可以修改积分的方法请告知，我想免费分享给大家。
 

1. AD7793硬件SPI驱动

单片机型号为：MSP430F57XX

硬件SPI驱动失败的几个原因有：单片机配置SPI资源错误（包括SPI的时钟，SPI的运行模型等配置错误），单片机的系统时钟配置错误（注意MCLK, SMCLK, ACLK的分配）

1.1 SPI read with AD7793

/******************** SPI read with AD7793 ***********************/
void AD7793_R(unsigned char addr, unsigned char *buffer, int n)
{
  unsigned int index;
  unsigned char temp;
  AD7793_CS_DIS;
  __delay_cycles(200); 
  AD7793_CS_EN;
  
  // t1>0ns
  __delay_cycles(200); 

  // send address
  while(!(UCB0IFG & UCTXIFG));              
    UCB0TXBUF = addr;
  while(!(UCB0IFG & UCRXIFG));            
    temp = UCB0RXBUF;
  // Delay > 10us, after writing to RAM
  Delay10us(2);  
  
  // Read data from register and load in buffer[]
  for(index=0; index < n; index++)
  {
    while(!(UCB0IFG & UCTXIFG));              
    UCB0TXBUF = 0x00;
    while(!(UCB0IFG & UCRXIFG));            
    buffer[index] = UCB0RXBUF;
    Delay10us(100);
  }
  
  AD7793_CS_DIS;
}

1.2 SPI write with AD7793

/******************** SPI write with AD7793 ***********************/
void AD7793_W(unsigned char addr, unsigned char *buffer, char n)
{
  unsigned char index;
  
  AD7793_CS_EN;
  
  // t1>0ns
  __delay_cycles(200); 

  // send address
  while(!(UCB0IFG & UCTXIFG));              
  UCB0TXBUF = addr;
  
  // Delay > 10us, after writing to RAM
  Delay10us(2);  
  
  // Read data from register and load in buffer[]
  for(index=0; index < n; index++)
  {
    while(!(UCB0IFG & UCTXIFG));            
    UCB0TXBUF = buffer[index];
  }
   AD7793_CS_DIS;  
}

1.3 AD7793 相关寄存器配置

/******************** AD7793 Configuration ***********************/
void AD7793_CON(void)
{
  AD7793_CS_EN;
  
  //single model
  SPI_Data[0] = 0x20;	
  
  //64k intenal CLK，4.17Hz update rate（stable time 500ms）
  SPI_Data[1] = 0x0f;                   

  //Model regeister
  AD7793_W(0x08, SPI_Data, 2);	
  
  AD7793_CS_DIS;  
}

1.4 电压测量

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/******************** voltage measurement ***********************/
void V_measure (void)
{
 /*** Read the both sides voltage of RTD ***/
  
  //bioplar encoding, 8 times, input range 312.5mV
  //external reference voltage, buffer mode, AIN1 input
  AD7793_CON();
  SPI_Data[0] = 0x03;						
  SPI_Data[1] = 0x10;                     
  AD7793_W(0x10, SPI_Data, 2);	
  
  //IEXC1,IEXC2 connected with IOUT1，current is 210uA
  //IO register	
  SPI_Data[0] = 0x0E;						
  AD7793_W(0x28, SPI_Data, 1);			

  //data register
  AD7793_R(0x58, SPI_Data, 3);			

  //get the temperature values
  ad_result_T = SPI_Data[0];
  ad_result_T <<= 8;
  ad_result_T += SPI_Data[1];
  ad_result_T <<= 8;
  ad_result_T += SPI_Data[2];
  ad_result_T &= 0x00ffffff;
  ad_result_T -= 8388608;
  T =(float)ad_result_T*3.7104E-5;
  
 /*** Read the ambient temperature ***/
  
  //bioplar encoding, 8 times, input range 312.5mV
  //external reference voltage, buffer mode, AIN1 input
  SPI_Data[0] = 0x00;						
  SPI_Data[1] = 0x86;                     
  AD7793_W(0x10, SPI_Data, 2);			

  //data register
  AD7793_R(0x58, SPI_Data, 3);			

  //get the ambient temperature
  ad_result_T1 = SPI_Data[0];
  ad_result_T1 <<= 8;
  ad_result_T1 += SPI_Data[1];
  ad_result_T1 <<= 8;
  ad_result_T1 += SPI_Data[2];
  ad_result_T1 &= 0x00ffffff;
  ad_result_T1 -= 8388608;
  Tenvir =(float)ad_result_T1*3.7104E-5;
}

2. AD7793模拟SPI驱动

模拟SPI驱动失败的最主要原因是：时钟！时钟！时钟！注意时钟的配置和延时的处理

2.1 AD7793基础子函数的处理

void AD7793_CS_SET()//CS置1
{
    P1OUT |= BIT1; 
}
void AD7793_CS_CLR()//CS置0
{
    P1OUT &=~ BIT1; 
}
void AD7793_SCLK_SET()
{
    P2OUT |= BIT2; 
}
void AD7793_SCLK_CLR()
{
    P2OUT &=~ BIT2; 
} 
void AD7793_DIN_SET()
{
    P1OUT |= BIT6;
}
void AD7793_DIN_CLR()
{
    P1OUT &=~ BIT6;
}
unsigned int AD7793_DOUT_GET()
{
    unsigned int i;
    if(P1IN & BIT7)
      i = 1;
    else
      i = 0;
    return i;
}

2.2 向AD7793写入一个字节

void WriteToReg(unsigned char ByteData) //向AD7793写入一个字节
{
    unsigned char temp;
    unsigned char i;
    AD7793_CS_CLR();
    AD7793_SCLK_SET();
    temp=0x80;
    for(i=0;i<8;i++)
    {
        if((temp & ByteData)==0)
        {
            AD7793_DIN_CLR();
        }
        else
        {
            AD7793_DIN_SET();
        }
        AD7793_SCLK_CLR();
        Delay();
        AD7793_SCLK_SET();
        Delay();
        temp=temp>>1;
    }
    AD7793_CS_SET();
}

2.3 复位AD7793

void AD7793_Reset(void)//AD7793复位
{
    P1DIR |= BIT6;      
    P2DIR |= BIT2;
    P1DIR &=~ BIT7;
    
    unsigned int ResetTime;
    ResetTime = 32;
    AD7793_SCLK_SET();
    AD7793_CS_CLR();
    AD7793_DIN_SET();
    while(ResetTime--)
    {
        Delay();
        AD7793_SCLK_CLR();
        Delay();
        AD7793_SCLK_SET();
    }
    AD7793_CS_SET();
}

2.4 读取AD7793

unsigned char AD7793_ReadStatusRegister(void) //读取7793的状态寄存器
{
    unsigned char j;
    unsigned char temp;
    WriteToReg(0x40);
    AD7793_DIN_SET();
    AD7793_CS_CLR();
    temp=0;
    for(j=0; j<8; j++)
    {
        AD7793_SCLK_CLR();
        if(AD7793_DOUT_GET()==0)
        {
            temp=temp<<1;
        }
        else
        {
            temp=temp<<1;
            temp=temp+0x01;
        }
        Delay();
        AD7793_SCLK_SET();
        Delay();
    }
    AD7793_CS_SET();
    return temp;
}

2.5 配置相关寄存器

void Ad7793_WriteModeRegister(unsigned char ModeRegisterH,unsigned char ModeRegisterL)
//配置模式寄存器
{
    WriteToReg(0x08);
    WriteToReg(ModeRegisterH);
    WriteToReg(ModeRegisterL);
}
void Ad7793_WriteConfigRegister(unsigned char ConfigRegisterH,unsigned char ConfigRegisterL)
//配置配置寄存器
{
    WriteToReg(0x10);
    WriteToReg(ConfigRegisterH);
    WriteToReg(ConfigRegisterL);
}
void Ad7793_WriteIORegister(unsigned char IORegister)
//配置IO寄存器
{
    WriteToReg(0x28);
    WriteToReg(IORegister);
}

2.6 读取AD7793数据寄存器

long AD7793_ReadDataRegister(void)
{
union
{
    unsigned char chardata[3];
    unsigned long longdata;
}AD7793Result;

    unsigned char i,j;
    unsigned char temp;
    temp=AD7793_ReadStatusRegister();
    while((temp&0x80)==0x80)
    {
        temp=AD7793_ReadStatusRegister();
    }
    WriteToReg(0x58);
    AD7793_DIN_SET();
    AD7793_CS_CLR();
    for(i=0; i<3; i++)
    {
        for(j=0; j<8; j++)
        {
            AD7793_SCLK_CLR();
            if(AD7793_DOUT_GET()==0)
            {
                temp=temp<<1;
            }
            else
            {
                temp=temp<<1;
                temp=temp+0x01;
            }

        Delay();
        AD7793_SCLK_SET();
        Delay();
        }
        AD7793Result.chardata[3-i]=temp;
    }
    AD7793_CS_SET();
    AD7793Result.longdata=AD7793Result.longdata>>8;
    return AD7793Result.longdata;
}

2.7 初始化AD7793

void Init_AD7793(void)//AD7793的初始化
{
    AD7793_CS_SET();
    AD7793_Reset();
    Ad7793_WriteModeRegister(0x00,0x0F);//连续转换
    Ad7793_WriteConfigRegister(0x03,0x10);//292.5mv，1.65V偏压
    Ad7793_WriteIORegister(0x0E);
}