MSP430普通I/0口模拟IIC总线

#define SLAVE_ADDRESS           0x04
#define SLAVE_WRITE_ADDRESS     (SLAVE_ADDRESS<<1)|0x00
#define SLAVE_READ_ADDRESS      (SLAVE_ADDRESS<<1)|0x01

#define I2C_SDA     BIT3
#define I2C_SCL     BIT4
#define I2C_PORT_IN    P6IN
#define I2C_PORT_OUT   P6OUT
#define I2C_PORT_DIR   P6DIR

#define SDA_IN     (I2C_PORT_IN & I2C_SDA)
#define SCL_IN     (I2C_PORT_IN & I2C_SCL)
#define S_SDA     I2C_PORT_DIR &= ~I2C_SDA
#define C_SDA     I2C_PORT_DIR |= I2C_SDA;I2C_PORT_OUT &= ~I2C_SDA
#define S_SCL     I2C_PORT_DIR &= ~I2C_SCL
#define C_SCL     I2C_PORT_DIR |= I2C_SCL;I2C_PORT_OUT &= ~I2C_SCL

void I2C_init(void)
{
    I2C_PORT_DIR &= ~(I2C_SDA|I2C_SCL);
 I2C_PORT_OUT |= (I2C_SDA|I2C_SCL);
}

void I2C_DELAY(void)
{
    asm("nop");asm("nop");
 asm("nop");asm("nop");
 asm("nop");asm("nop");
 asm("nop");asm("nop");
}

void I2C_Start(void)
{
 S_SDA;
 S_SCL;
 I2C_DELAY();
 C_SDA;
 I2C_DELAY();
 C_SCL;
}

void I2C_Stop(void)
{ 
 C_SDA;
 I2C_DELAY();
 S_SCL;
 I2C_DELAY();
 S_SDA;
 I2C_DELAY();
}

void I2C_Send_Ack(void)
{
 C_SDA;
 I2C_DELAY();
 S_SCL;
 I2C_DELAY();
 C_SCL;
 I2C_DELAY();
}

void I2C_Send_NoAck(void)
{
 S_SDA;
 I2C_DELAY();
 S_SCL;
 I2C_DELAY();
 C_SCL;
 I2C_DELAY();
}

void I2C_Read_Ack(void)
{
    unsigned char i = 0;
 S_SCL;
 S_SDA;
 I2C_DELAY();
 for(i=0; i<100; i++) 
    {
  if(SDA_IN == 0) 
        {
   I2C_DELAY(); break;
  }
  I2C_DELAY();
 }
 C_SCL;
 I2C_DELAY();
}

void I2C_WriteByte(unsigned char one_byte)
{
    unsigned char i = 0;
 S_SDA;
 for (i=0; i<8; i++) 
    {
        if (one_byte&0x80) 
        {
            S_SDA; 
        }
        else 
        {
            C_SDA;
        }
        one_byte<<=1;
        I2C_DELAY();
        S_SCL;
        I2C_DELAY();
        C_SCL;
        I2C_DELAY();
 }
}

unsigned char I2C_ReadByte(void)
{
 unsigned char read_byte=0;
    unsigned char i = 0; 
 S_SDA;
 //C_SCL;
 I2C_DELAY();
 for (i=0; i<8; i++)
    {
  S_SCL;
  I2C_DELAY();
  read_byte<<=1;
  if (SDA_IN != 0)
  {
   read_byte |= 0x01;
  }
  //I2C_DELAY;
  C_SCL;
  I2C_DELAY();
 }
 return read_byte;
}

void I2C_write_Nbyte(unsigned char *pbuf, unsigned char cnt)
{
    unsigned char i = 0;
 I2C_Start();
 I2C_WriteByte(SLAVE_WRITE_ADDRESS);
 I2C_Read_Ack();
 for (i=0; i     {
  I2C_DELAY();I2C_DELAY();
  I2C_WriteByte(*pbuf);
  pbuf++;
  I2C_Read_Ack();
 }
 I2C_Stop();
}

void I2C_read_Nbyte(unsigned char *pbuf, unsigned char cnt)
{
    unsigned char i = 0;
 I2C_Start();
 I2C_WriteByte(SLAVE_READ_ADDRESS);
 I2C_Read_Ack();
 for (i=1; i     {
  I2C_DELAY();I2C_DELAY();
  *pbuf = I2C_ReadByte();
  pbuf++;
  I2C_Send_Ack();
 }
 *pbuf = I2C_ReadByte();
 I2C_Stop();
}