24C02、24C16进行字节、页读取、页存取操作

以下这篇文章是自己折腾了三天存储芯片后，并且能够成功进行字节操作、页操作的一篇应用型文章，不太想研究原理的可以直接采用本文的代码和注意事项。 

在对24C02或者24C16进行字节、页读取、页存取前，我们需要弄清楚I²C协议、24C02/24C16存储空间、字节操作和页操作的时序

• I²C协议:I²C是什么协议网上进行百度方可知道，以下只写使用代码

void i2cStart(void)            //开始时序
{
  SDA=1;
  SCL=1;
  _delay(2);  //延时2μs
  SDA=0;
  _delay(2); 
  SCL=0;
}

void i2cStop(void)            //结束时序
{
  SDA=0;
  _delay(2);
  SCL=1;
  _delay(2);
  SDA=1;
}

void i2cAck_MCU(void)        //应答时序
{
  SDA=0;
  _delay(2);
  SCL=1;
  _delay(2);
  SCL=0;
  _delay(2);
  SDA=1;
  _delay(4);
}


void i2cNoAck_MCU(void)      //非应答时序
{
  SDA=1;
  _delay(2);
  SCL=1;
  _delay(2);
  SCL=0;
  _delay(2);
}

• 24C02/24C16存储空间大小

24C02就是有2Kbit = 2000/8 = 250个字节，24C16就是有16kbit  = 2000个字节，24C02一页最多可以写入8个字节，因此可以分成32页，24C16一页最多可以写入16个字节，因此可以分成128页。

• 字节写操作

  void WriteByte_24LC16B(unsigned char input)
  {
    unsigned char bit_count;
    for(bit_count=8;bit_count!=0;bit_count--)
    {
      _delay(2);
      SDA=(_Bool)(input&0x80);
      _delay(2);
      SCL=1;
      _delay(2);
      SCL=0;
      input=input<<1;
      _delay(2);
    }
    SDA=1;
    SDA_CTRL=1;	//这里需要看自己使用的芯片设置SDA的IO口为输入状态，我用的是HT45F67芯片，SDA端口设置为输入状态，用于判断SDA是否接到主机的应答信号
    _delay(2);
    SCL=1;
    _delay(2);
    if(SDA == 1)
    	ack = 0;
    else
      ack = 1;
    SCL=0;
    SDA_CTRL=0;    //此处根据自己所使用的芯片将SDA所在的Io口设置为输出状态
  }
  
  void Write_24LC16B(unsigned char Wdata,unsigned int RomAddress)
  {
    unsigned char block;
    WriteDeviceAddress=0B10100000;
    block=RomAddress/256;
    RomAddress=RomAddress%256;
    WriteDeviceAddress=WriteDeviceAddress|(block<<1);
    i2cStart();
    WriteByte_24LC16B(WriteDeviceAddress);
    WriteByte_24LC16B((unsigned char)RomAddress);
    WriteByte_24LC16B(Wdata);
    i2cStop();
    _delay(5500);
  }

  字节读操作

• unsigned char ReadByte_24LC16B()
  {
    unsigned char bit_count,rbyte=0;
    SDA=1;
    SDA_CTRL=1;
    _delay(10);
    for(bit_count=8;bit_count!=0;bit_count--)
    {
      rbyte=rbyte<<1;
      _delay(2);
      SCL=1;
      rbyte=rbyte|((unsigned char)(SDA));
      _delay(2);
      SCL=0;
      _delay(2);
    }
    SDA_CTRL=0;
    return(rbyte);
  }
  
  
  unsigned char Read_24LC16B(unsigned int RomAddress)
  {
    unsigned char output,block;
    ReadDeviceAddress=0B10100001;
    WriteDeviceAddress=0B10100000;
    block=RomAddress/256;
    RomAddress=RomAddress%256;
    WriteDeviceAddress=WriteDeviceAddress|(block<<1);
    ReadDeviceAddress=ReadDeviceAddress|(block<<1);
    i2cStart();
    WriteByte_24LC16B(WriteDeviceAddress);
    WriteByte_24LC16B((unsigned char)RomAddress);
    i2cStart();
    WriteByte_24LC16B(ReadDeviceAddress);
    output=ReadByte_24LC16B();
    i2cNoAck_MCU();
    i2cStop();
    _delay(2000);
    return(output);  
  }

  页写操作

  Wdata为输入数组的首地址，RomAddress为需要进行存储的地址，范围在0~2047之间，cnt为一次需要写入的字节个数，建议采用8的倍数的cnt，因为本函数不采用自动分页，不是8的倍数会在超出页写入最多的字节数之后覆盖掉原来的数。
  void WritePage_24LC16B(unsigned char *Wdata,unsigned int RomAddress,unsigned char cnt)
  {
    unsigned char block;
    WriteDeviceAddress=0B10100000;
    block=RomAddress/256;
    RomAddress=RomAddress%256;
    WriteDeviceAddress=WriteDeviceAddress|(block<<1);
    i2cStart();
    WriteByte_24LC16B(WriteDeviceAddress);
    WriteByte_24LC16B((unsigned char)RomAddress);
    while(cnt--)
    {
    	WriteByte_24LC16B(*Wdata++);
    }
    i2cStop();
  }
  
  注意:连续进行多页写操作，需要在WritePage_24LC16B函数后添加150μs以上的延迟，这段时间，24C02内部需要将数据存储到芯片内部。
  例子:
  D_buffer[8] = {1,2,3,4,5,6,7,8};
  WritePage_24LC16B(D_buffer,0,8);
  _delay(150);        //延迟150μs以及以上
  WritePage_24LC16B(D_buffer,8,8);
  

   

• 页读操作

• void ReadPage_24LC16B(unsigned char *Rdata,unsigned int RomAddress,unsigned char cnt)
  {
    unsigned char block;
    ReadDeviceAddress=0B10100001;
    WriteDeviceAddress=0B10100000;
    block=RomAddress/256;
    RomAddress=RomAddress%256;
    WriteDeviceAddress=WriteDeviceAddress|(block<<1);
    ReadDeviceAddress=ReadDeviceAddress|(block<<1);
    i2cStart();
    WriteByte_24LC16B(WriteDeviceAddress);
    WriteByte_24LC16B((unsigned char)RomAddress);
    i2cStart();
    WriteByte_24LC16B(ReadDeviceAddress);
    while(cnt>1)
    {
    	*Rdata++ = ReadByte_24LC16B();
    	cnt--;
    	i2cAck_MCU();			//发送完读地址后，需要应答一下
    }
    *Rdata = ReadByte_24LC16B();
    i2cNoAck_MCU();			//读取最后一个字节需要非应答
    i2cStop();
    _delay(2000);
  }