AT89S52单片机模拟I2C总线协议读写AT24C04 -

标题: AT89S52单片机模拟I2C总线协议读写AT24C04 [打印本页]

作者: 51黑tt 时间: 2016-3-6 13:31
标题: AT89S52单片机模拟I2C总线协议读写AT24C04
   I2C总线是2条线总线.数据线SDA,时钟线SCL.结构简单.
   AT24C04是具有I2C总线接口的EEPROM.大小为512*8bit.单片机AT89S52本身不具有I2C总线结口,所以可编写程序用并行端口模拟I2C总线协议读写AT24C04.
   多个设备通信的重点（１．电平的区别，如串口通信中ＰＣ与单片机通信,PC机[color=#cc0033]串口电平[/color]值为+12V~-12V，单片机为ＴＴＬ电平0V~+5V.，所以要用电平转换芯片转电平．２，通信协议．（串口通信协议））
   具体的协议内容与数据格式可查资料.
代码如下:
#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; //一样P0.0亮

}
else
{
PP = 0;  //不一样P0.1亮
}
write = 0;
  }
}
}

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