標(biāo)題: AT89S52單片機(jī)模擬I2C總線協(xié)議讀寫AT24C04 [打印本頁]

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作者: 51黑tt    時(shí)間: 2016-3-6 13:31
標(biāo)題: AT89S52單片機(jī)模擬I2C總線協(xié)議讀寫AT24C04
      I2C總線是2條線總線.數(shù)據(jù)線SDA,時(shí)鐘線SCL.結(jié)構(gòu)簡(jiǎn)單.  
      AT24C04是具有I2C總線接口的EEPROM.大小為512*8bit.單片機(jī)AT89S52本身不具有I2C總線結(jié)口,所以可編寫程序用并行端口模擬I2C總線協(xié)議讀寫AT24C04.
     多個(gè)設(shè)備通信的重點(diǎn)（１．電平的區(qū)別，如串口通信中ＰＣ與單片機(jī)通信,PC機(jī)[color=#cc0033]串口電平[/color]值為+12V~-12V，單片機(jī)為ＴＴＬ電平0V~+5V.，所以要用電平轉(zhuǎn)換芯片轉(zhuǎn)電平．２，通信協(xié)議．（串口通信協(xié)議））
      具體的協(xié)議內(nèi)容與數(shù)據(jù)格式可查資料.
代碼如下:
#include <reg52.h>
#define WriteDeviceAddress 0xa0
#define ReadDeviceAddress 0xa1
sbit SCL = P3^4;
sbit SDA = P3^5;
sbit DOG = P0^0;
sbit PP = P0^1;
sbit DOG1 = P0^7;
void DelayMs(unsigned int number)
{
  unsigned char tmp;
  for(;number!=0;number--,DOG1=!DOG1)
  {
   for(tmp=112;tmp!=0;tmp--)
   {
   }
  }
}
void Start()
{
  SDA = 1;
  DelayMs(1);
  SCL = 1;
  DelayMs(1);
  SDA = 0;
  DelayMs(1);
  SCL = 0;
  DelayMs(1);
}
bit Write8bit(unsigned char input)
{
  unsigned char tmp;
  for(tmp =8;tmp!=0;tmp--)
  {
   SDA = (bit)(input&0x80);
   DelayMs(1);
   SCL = 1;
   DelayMs(1);
   SCL = 0;
   DelayMs(1);
   input = input << 1;
  }
  return 1;
}
bit TestAck()
{
  bit ErrorBit;
  SDA = 1;
  DelayMs(1);
  SCL = 1;
  DelayMs(1);
  ErrorBit = SDA;
  DelayMs(1);
  SCL = 0;
  DelayMs(1);
  return(ErrorBit);
}
void Stop()
{
  SCL = 0;
  DelayMs(1);
  SDA = 0;
  DelayMs(1);
  SCL = 1;
  DelayMs(1);
  SDA = 1;
  DelayMs(1);
}
void WriteI2C(unsigned char *Wdata, unsigned char RomAddress, unsigned char number)
{
  Start();
  Write8bit(WriteDeviceAddress);
  TestAck();
  Write8bit(RomAddress);
  TestAck();
  for(;number!=0;number--)
  {
   Write8bit(*Wdata);
   TestAck();
   Wdata++;
  }
  Stop();
  DelayMs(1);
}
unsigned char Read8Bit()
{
unsigned char tmp,rbyte = 0;
for(tmp=8;tmp!=0;tmp--)
{
  SCL = 1;
  DelayMs(1);
  rbyte = rbyte << 1;
  DelayMs(1);
  rbyte = rbyte|((unsigned char)(SDA));
  SCL = 0;
  DelayMs(1);
}
return(rbyte);
}
void Ack()
{
SDA = 0;
DelayMs(1);
SCL = 1;
DelayMs(1);
SCL = 0 ;
DelayMs(1);
SDA = 1;
DelayMs(1);
}
void NoAck()
{
SDA = 1;
DelayMs(1);
SCL = 1;
DelayMs(1);
SCL = 0 ;
DelayMs(1);
}
void ReadI2C(unsigned char* RamAddress,unsigned char RomAddress,unsigned char bytes)
{
Start();
Write8bit(WriteDeviceAddress);
TestAck();
Write8bit(RomAddress);
TestAck();
Start();
Write8bit(ReadDeviceAddress);
TestAck();
while(bytes != 1)
{
  *RamAddress = Read8Bit();
  Ack();
  RamAddress++;
  bytes--;
}
  *RamAddress = Read8Bit();
NoAck();
Stop();
}
void main()
{
unsigned char writeByte[8] = {0xC0,0X34,0X12,0X22,0X11,0X01,0X00,0X00};
unsigned char readByte[8];
unsigned char *addw;
unsigned char *addr;
unsigned char i;
unsigned char ok = 0;
bit write = 1;
DOG = 1;

while(1)
{
  if(write == 1)
  {
   addw = writeByte;
   addr = readByte;
   WriteI2C(addw,0x00,8);
   ReadI2C(addr,0x00,8);
   for(i=0;i<8;i++)
   {
    if(writeByte[i] == readByte[i])
    {
     ok++;
    }
   }
   if(ok == 8)
   {
    DOG = 0;   //一樣P0.0亮
   
   }
   else
   {
    PP = 0;  //不一樣P0.1亮
   }
   write = 0;
  }
}
}

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