2019年10月30日 | MSP430杂谈--AD7745硬件IIC驱动与模拟IIC驱动

和上一篇AD7793类似，项目中也涉及到利用AD7745读取电容值，来测环境湿度。编写了基于MSP430的AD7745的硬件IIC驱动和模拟IIC驱动，分享给大家。

AD7745硬件IIC驱动完整版下载链接：https://download.csdn.net/download/qq_42580947/11041942

AD7745模拟IIC驱动完整版下载链接：https://download.csdn.net/download/qq_42580947/11041947

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. AD7745的硬件IIC驱动

MCU：MSP430F57XX

AD7745的硬件IIC驱动失败的几个原因有：单片机配置IIC资源错误（包括IIC的时钟，IIC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 AD7745的写函数

void AD7745_W(unsigned char addr, unsigned char data)

{

  while(UCB0STAT& UCBBUSY)

    InitUCB0();

  UCB0CTL1 |= UCTR;

  UCB0CTL1 |= UCTXSTT;   

  UCB0TXBUF = addr;

  delayus(200);

  while(!(UCB0IFG & UCTXIFG0));

  UCB0TXBUF = data;

  delayus(200);

  while(!(UCB0IFG & UCTXIFG0));

  UCB0CTL1 |= UCTXSTP;

  while (UCB0CTL1 & UCTXSTP);

}

1.2 AD7745的读函数

void AD7745_R(unsigned char addr, unsigned char *buffer, char n)

{

  unsigned char index;

  UCB0CTL1 |= UCTR;

  UCB0CTL1 |= UCTXSTT; 

  delayus(200);

  UCB0TXBUF = addr;

  delayus(200);

  while(!(UCB0IFG & UCTXIFG0));

  while (UCB0CTL1 & UCTXSTP);

  UCB0CTL1 &=~ UCTR;

  RXByteCtr = n;

  UCB0CTL1 |= UCTXSTT;  

  delayus(200);

  while (UCB0CTL1 & UCTXSTP);

  for(index=0; index < n-1; index++)

  {

    while(!(UCB0IFG & UCRXIFG0));            

    *buffer++ = UCB0RXBUF;

    delayus(200);

  }

  UCB0CTL1 |= UCTXSTP+UCTXNACK;

  delayus(200);

  while((UCB0IFG&UCRXIFG)==0);

  *buffer = UCB0RXBUF;

  delayus(200);

  while (UCB0CTL1 & UCTXSTP); 

}

1.3 AD7745的复位

void Reset_AD7745()

{

  while(UCB0STAT& UCBBUSY)

    InitUCB0();

  UCB0CTL1 |= UCTR;

  UCB0CTL1 |= UCTXSTT; 

  delayus(200);

  UCB0TXBUF = 0xBF;

  while(!(UCB0IFG & UCTXIFG0));

  UCB0CTL1 |= UCTXSTP;

  while (UCB0CTL1 & UCTXSTP); 

}

1.4 AD7745的初始化

void Init_AD7745(void)

{

  AD7745_W(0x0D, offset_buf[0]);

  AD7745_W(0x0E, offset_buf[1]);

  capdac_offset = Capdac_Parameter;                           

  out_buff[4] = 0x80+capdac_offset;               //CAPDACA is set to capdac_offset

  out_buff[5] = 0x80;                             //CAPDACB is set to 0

  CAPDAC = (float)(capdac_offset*CAPDAC_UNIT);   //CAPDAC只会取4值，即4.25，8.5，12.75，17

  AD7745_W(0x07, out_buff[0]);                    // data collect

  AD7745_W(0x08, out_buff[1]);

  AD7745_W(0x09, out_buff[2]);

  AD7745_W(0x0A, out_buff[3]);

  AD7745_W(0x0B, out_buff[4]); 

  AD7745_W(0x0C, out_buff[5]);

  memset(DataArr,0,sizeof(float)*DataNumber);

}

1.5 读取测量数据

void ReadData(void)

{

  AD7745_R(0x01, in_buff, sizeof(in_buff));  // read the data register

  CDC_Register_data = in_buff[1];

  CDC_Register_data = 0;

  CDC_Register_data = in_buff[1];

  CDC_Register_data <<= 8;

  CDC_Register_data += in_buff[2];

  CDC_Register_data <<= 8;

  CDC_Register_data += in_buff[0];

  CDC_Register_data &= 0x00ffffff;

  CDC_Capacitance2 = (float)(FULL_SCALE-SEMI_SCALE);

  if(CDC_Register_data>= SEMI_SCALE)

  {

      CDC_Capacitance1 = (float)(CDC_Register_data-SEMI_SCALE);

      CDC_Capacitance = 4.096 * (CDC_Capacitance1/CDC_Capacitance2);

  }

  else

  {

      CDC_Capacitance1 = (float)(SEMI_SCALE-CDC_Register_data);

      CDC_Capacitance = -4.096 * (CDC_Capacitance1/CDC_Capacitance2);

  }

  CDC_Capacitance = CAPDAC+CDC_Capacitance;

  Capacitance  = CDC_Capacitance;

}

2. AD7745模拟IIC驱动

模拟IIC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 AD7745基础子函数的处理

void start()

{

    SCL_OUT;

    SDA_OUT;

    SDA_H;

    delayms(1);

    SCL_H;

    delayms(1);

    SDA_L;

    delayms(1);

    SCL_L;

    delayms(1);

}

void stop()

{

  SDA_OUT;

  SCL_OUT;

  SDA_L;

  delayms(1);

  SCL_H;

  delayms(1);

  SDA_H;

  delayms(1);

}

void Ack()

{

  SDA_OUT;

  SCL_OUT;

  SCL_L;

  SDA_L;

  delayms(1);

  SCL_H;

  delayms(1);

  SCL_L;

}

void NAck()

{

  SDA_OUT;

  SCL_OUT;

  SCL_L;

  SDA_H;

  delayus(2);

  SCL_H;

  delayus(2);

  SCL_L;

}

unsigned int WAck()

{

    SDA_H;

    SDA_IN;

    SCL_H;

    while(P1IN & BIT6)

    {

    }

  SCL_L;

  delayms(1);

  return 0;

}

1.2 读取字节数据

uchar read_byte()

{

  uchar i,read_data;

  SDA_OUT;

  SCL_L;

  SDA_H;

  for(i = 0;i<8;i++)

  {

    SDA_H;

    delayus(2);

    SCL_H;

    SDA_IN;

    delayus(2);

    read_data <<= 1;

    if(P1IN & BIT6)

      read_data |= 0x01;

    SDA_OUT;

    SCL_L;   

  }

  delayms(5);

  return(read_data);

}

1.3 写字节数据

void write_byte(uint data)

{

  uchar i;

  SCL_OUT;

  SDA_OUT;

  for(i = 0;i<8;i++)

  {

    if(data & 0x80)

      SDA_H;

    else

      SDA_L; 

    delayms(1);

    SCL_H;

    delayms(1);

    SCL_L;

    delayms(1);

    data = data << 1;

  }

  delayms(5);

}

1.4 向指定地址写数据

void write_dat(uchar addr,uchar write_data)

{

  start();

  write_byte(OP_WRITE);

  WAck();

  write_byte(addr);

  WAck();

  write_byte(write_data);

  WAck();

  stop();

  delayus(1000);

}

1.5 从指定地址读数据

uchar read_random(uint random_addr)

{

  uchar i;

  start();

  write_byte(OP_WRITE);

  WAck();

  write_byte(random_addr);

  WAck();

  start();

  write_byte(OP_READ);

  WAck();

  i = read_byte();

  stop();

  return i;

}

1.6 AD7745的初始化

void Init_AD7745()

{

  start();

  write_byte(0X09);

  WAck();

  write_byte(0xBF);

  delayus(500);

  WAck();

  stop();

}

1.7 写数组与读数组

void EEPROM_WriteArray (unsigned char dest_addr, unsigned char* src_addr,

                        unsigned char len)

{

   unsigned char i;

   start();

   write_byte(OP_WRITE);

   WAck();

   write_byte(dest_addr);

   WAck();

   for( i = 0; i < len; i++ )

   {

   write_byte(src_addr[i]);

   WAck();

   }

   stop();

   delayus(1000);

}

void EEPROM_ReadArray (unsigned char* dest_addr, unsigned char src_addr,

                       unsigned char len)

{

  uchar i;

  start();

  write_byte(OP_WRITE);

  WAck();

  write_byte(src_addr);

  WAck();

  start();

  write_byte(OP_READ);

  WAck();

  for( i = 0; i < len; i++ )

  {

    dest_addr[i] = read_byte();

    if(i!=len-1)

    Ack();

    else

    NAck();

  }

    stop();

}

1.8 AD7745的配置

void Capdacsetup(void)

{

   EEPROM_WriteArray(0x0D, offset_buf, sizeof(offset_buf));      // OFFSET寄存器初始化

   Capdac_Parameter = 127;

   capdac_offset = Capdac_Parameter;                           

   out_buff[4] = 0x80+capdac_offset;                            

   out_buff[5] = 0x80;                                         //CAPDACB is set to 0

   CAPDAC = (float)(capdac_offset*CAPDAC_UNIT);                                 

   EEPROM_WriteArray(0x07, out_buff, sizeof(out_buff));         // data collect

   memset(DataArr,0,sizeof(float)*DataNumber);

}

1.9 读取测量数据

void ReadData(void)

{

EEPROM_ReadArray(in_buff, 0x01, sizeof(in_buff));  // read the data register

CDC_Register_data = 0;

CDC_Register_data = in_buff[0];

CDC_Register_data <<= 8;

CDC_Register_data += in_buff[1];

CDC_Register_data <<= 8;

CDC_Register_data += in_buff[2];

CDC_Register_data &= 0x00ffffff;

CDC_Capacitance2 = (float)(FULL_SCALE-SEMI_SCALE);

if(CDC_Register_data>= SEMI_SCALE)

{

CDC_Capacitance1 = (float)(CDC_Register_data-SEMI_SCALE);

CDC_Capacitance = 4.096 * (CDC_Capacitance1/CDC_Capacitance2);

}

else

{

CDC_Capacitance1 = (float)(SEMI_SCALE-CDC_Register_data);

CDC_Capacitance = -4.096 * (CDC_Capacitance1/CDC_Capacitance2);

}

CDC_Capacitance = CAPDAC+CDC_Capacitance;

DataArr[Int_dec++]=CDC_Capacitance;

if(Int_dec==DataNumber)

Int_dec=0;

}