IO模拟I2C

#include "reg52.h"

#define SDA P1^0

#define SCL P1^1

//延时函数，根据MCU时钟不同调整到1ms
void delay_ms(u16 x)
{
u8 i;
for(;x>0;x--)
{
  for(i=217;i>0;i--);
}

}

static void set_sda(u8 lev){

if(lev)
SDA = 1;
else
SDA = 0;
}
static void set_scl(u8 lev){


if(lev)
SCL = 1;
else
SCL = 0;
}

static void sda_input_mode(void){

// TODO  

}

 static void SomeNOP(void)
  {
  u16 i=14;

  while(i--);
  }
    
/*--------------------------------------------------------------------------------
I2C start
---------------------------------------------------------------------------------*/
static void I2CStart(void)
{
set_sda(1);
set_scl(1);
SomeNOP();//INI
set_sda(0);
SomeNOP(); //START
set_scl(0);
}

/*--------------------------------------------------------------------------------
I2C stop
---------------------------------------------------------------------------------*/
static void I2CStop(void)
{
set_sda(0);
SomeNOP(); //INI
set_scl(1);
SomeNOP();
set_sda(1); //STOP
}

/*--------------------------------------------------------------------------------
 check ACK
---------------------------------------------------------------------------------*/
static u8 WaitAck(void)
{
u8 errtime=255; //ACK timeout count
set_sda(1);
SomeNOP();
set_scl(1);
SomeNOP();
sda_input_mode();
SomeNOP();
while(SDA)
 { errtime--;
 if(!errtime)
 {  I2CStop();
return 1;
 }
 }
set_scl(0);
return 0;
}
/*--------------------------------------------------------------------------------
 send no ACK
---------------------------------------------------------------------------------*/
static void SendNotAck(void)
 {
set_scl(1);
SomeNOP();
set_sda(1);  
SomeNOP();
set_scl(0);
 }
 /********************************************************
 send ACK
 *********************************************************/
static void SendAck(void)
 {
set_sda(0);
SomeNOP();
set_scl(1);
SomeNOP();
set_scl(0);
SomeNOP();
set_sda(1);
 }

/*--------------------------------------------------------------------------------
 write byte
---------------------------------------------------------------------------------*/
static void I2CSendByte(u8 ch)
{
u8 i=8;
while(i--)
{
set_scl(0);
SomeNOP();
if(ch&0x80)
set_sda(1);
else
set_sda(0);
ch