MSP430模拟IIC总线程序

只看该作者 · 2011-12-8 15:54

P4.7－－－SDA
P4.6－－－SCL
#include "msp430x44x.h"
#define SCL 0X40;
#define SDA 0X80;
#define Ram_addr 0x250;

int R_word;
int Ack_Flag;

void Delay(int m)
{
while(m-- > 0);
}

void Start(void)
{
  P4OUT = 0;
  P4DIR &= ~SCL;
  P4DIR &= ~SDA;//SET HIGH LEVEL
  P4DIR |= SDA;
  P4DIR |= SCL;

}

void Stop(void)
{
  P4DIR |= SDA;
  P4DIR &= ~SCL;
  P4DIR &= ~SDA;
  P4DIR |= SCL;
}

void Send_Byte(char Byte)
{
  int i;
  for (i=0;i<8;i++)
  {
if(Byte & 0x80)
{
   P4DIR &= ~SDA;
}
else
{
   P4DIR |= SDA;
}
P4DIR &= ~SCL;
Delay(50);
P4DIR |= SCL;
Byte = Byte << 1;
  }
}

void Ack(void)
{
  P4DIR &= ~SDA;
  P4DIR &= ~SCL;
  Ack_Flag = 0;
  Delay(10);
  if ((P4IN & 0x80))
  {
Ack_Flag = 1;
  }
  P4DIR |= SCL;
  Delay(10);
}

void NOAck(void)
{
  P4DIR &= ~SDA;
  Delay(10);
  P4DIR &= ~SCL;
  Delay(10);
  P4DIR |= SCL;
  Delay(10);
  P4DIR |= SDA;
}

void Receive_Byte(void)
{

  int j;
  R_word = 0x00;
  P4DIR &= ~SDA;
  for(j=0;j<8;j++)
  {
P4DIR &= ~SCL;
if(P4IN & 0x80)
{
   R_word |= 0x01;
}
else
{
   R_word &= 0xFE;
}
//Delay(50);
P4DIR |= SCL;
R_word = R_word << 1;
}
R_word = R_word >>1;
}

void I2C_Write(int W_addr,int word)
{

  while (1)
  {

Start();
Delay(20);
Send_Byte(0xA0);//write a byte :slave device
Ack();
if (Ack_Flag)
   continue;
Send_Byte(W_addr);// write a byte :e2prom address
Ack();
if(Ack_Flag)
   continue;

Send_Byte(word);
Ack();
if(!(Ack_Flag))
   break;
  }
  Stop();

}

void I2C_Random_Read(int R_addr)
{
  int *paddr;
  paddr = (int*)Ram_addr;
  while(1)
  {
Start();
Send_Byte(0xA0);
Ack();
if(Ack_Flag)
   continue;
Send_Byte(R_addr);
Ack();
if(Ack_Flag)
   continue;
Start();
Send_Byte(0xA1);
Ack();
if(!Ack_Flag)
   break;
}
  Receive_Byte();
  *paddr = R_word;
  NOAck();
  Stop();

}

void main(void)
{
  P4DIR = 0XFF;
  WDTCTL = WDTHOLD+WDTPW;
  while(1)

  {
I2C_Write(0x2A,0x10);
Delay(500);
I2C_Random_Read(0x2A);
}

}