MSP430学习的第一个模拟I2C程序

#include <msp430.h> 

unsigned char I2CBUF;

unsigned char checkbit;

#define SCL_H   (P10OUT |= BIT2)      // P10.2为SCL

#define SCL_L   (P10OUT &= ~BIT2)

#define SDA_H   (P10OUT |= BIT1)     //p10.1为SDA

#define SDA_L   (P10OUT &= ~BIT1)

#define SDA_OUT  (P10DIR |= BIT1)

#define SDA_IN  (P10DIR &= ~ BIT1)

void I2C_Start(void)    //I2C开始信号

{

 SDA_OUT;

 SCL_L;

 SDA_H;

 __delay_cycles(5);

 SCL_H;

 __delay_cycles(5);

 SDA_L;

 __delay_cycles(5);

 SCL_L;

 __delay_cycles(5);

}

unsigned char testACK(void) {

 SDA_IN;

 __delay_cycles(5);

 SCL_H;

 __delay_cycles(5);

 checkbit = (P10IN & BIT1) >> 4;

 __delay_cycles(5);

 SCL_L;

 __delay_cycles(5);

 return (checkbit);

}

void I2C_ACK(void)                //应答信号

{

 SDA_OUT;

 SCL_L;

 SDA_L;

 __delay_cycles(5);

 SCL_H;

 __delay_cycles(5);

 SCL_L;

 __delay_cycles(5);

 SDA_H;

}

void I2C_NACK(void) {

 SDA_OUT;

 SDA_H;

 __delay_cycles(5);

 SCL_H;

 __delay_cycles(5);

 SCL_L;

 __delay_cycles(5);

}

void I2C_STOP(void)             //产生结束信号

{

 SCL_L;

 __delay_cycles(5);

 SDA_L;

 __delay_cycles(5);

 SCL_H;

 __delay_cycles(5);

 SDA_H;

 __delay_cycles(5);

}

void I2C_WRITE(unsigned char data)

{

 SDA_OUT;

 unsigned char i;

 for (i = 8; i > 0; i--)      //高位循环8次，发送1个字节数据

    {

  if (data & 0x80)   //判断数据高位是0还是1

     {

   SDA_H;           //高位数据写1

  }

  else

  {

   SDA_L;

  }

  SCL_H;

  __delay_cycles(5);  //发送数据

  SCL_L;

  __delay_cycles(5);

  data <<= 1;

 }

}

unsigned char I2C_READ(void)

{

 unsigned char j;

 unsigned char BUFFER = 0X00;

 SDA_IN;

 for (j = 8; j >0; j--)      //高位循环8次，发送1个字节数据

    {

  SCL_H;

  __delay_cycles(5);

  BUFFER <<= 1;

  if ((P10IN & BIT1) == BIT1)   //判断数据高位是0还是1

  {

   BUFFER |= 0X01;         //高位数据写1

  }

  else

  {

   BUFFER |= 0XFE;

  }

  __delay_cycles(5);  //发送数据

  SCL_L;

  __delay_cycles(5);

 }

 return BUFFER;

}

void C16_WRITEDATA(unsigned char address, unsigned char DATA)

{

 I2C_Start();

 I2C_WRITE(address);

 testACK();

 I2C_ACK();

 I2C_WRITE(0x00);

 testACK();

 I2C_ACK();

 I2C_WRITE(DATA);

 I2C_STOP();

}

unsigned char C16_READEDATA(unsigned char address)

{

 unsigned char READDATA;

 I2C_Start();

 I2C_WRITE(0XA1);

 testACK();

 I2C_ACK();

 I2C_WRITE(address);

 I2C_Start();

 testACK();

 I2C_ACK();

 I2C_WRITE(0XA1);

 READDATA = I2C_READ();

 I2C_STOP();

 return READDATA;

}

int main(void)

{

    const int DATA = 0X88;

 unsigned char READBUFFER;

 WDTCTL = WDTPW + WDTHOLD;

 P10DIR |= BIT1 + BIT2;

 P2DIR |= BIT0;

 P2OUT &= ~BIT0;

 C16_WRITEDATA(0X00, DATA);

 __delay_cycles(5);

 READBUFFER = C16_READEDATA(0X00);

 while (1)

 {

  if (READBUFFER == 0X88)

  {

   P2OUT |= BIT0;

  } else {

   P2OUT &= ~ BIT0;

  }

  __delay_cycles(15);

 }

}