24C02、24C16進行字節、頁讀取、頁存取操作

以下這篇文章是自己折騰了三天存儲芯片後，並且能夠成功進行字節操作、頁操作的一篇應用型文章，不太想研究原理的可以直接採用本文的代碼和注意事項。 

在對24C02或者24C16進行字節、頁讀取、頁存取前，我們需要弄清楚I²C協議、24C02/24C16存儲空間、字節操作和頁操作的時序

• I²C協議:I²C是什麼協議網上進行百度方可知道，以下只寫使用代碼

void i2cStart(void)            //開始時序
{
  SDA=1;
  SCL=1;
  _delay(2);  //延時2μs
  SDA=0;
  _delay(2); 
  SCL=0;
}

void i2cStop(void)            //結束時序
{
  SDA=0;
  _delay(2);
  SCL=1;
  _delay(2);
  SDA=1;
}

void i2cAck_MCU(void)        //應答時序
{
  SDA=0;
  _delay(2);
  SCL=1;
  _delay(2);
  SCL=0;
  _delay(2);
  SDA=1;
  _delay(4);
}


void i2cNoAck_MCU(void)      //非應答時序
{
  SDA=1;
  _delay(2);
  SCL=1;
  _delay(2);
  SCL=0;
  _delay(2);
}

• 24C02/24C16存儲空間大小

24C02就是有2Kbit = 2000/8 = 250個字節，24C16就是有16kbit  = 2000個字節，24C02一頁最多可以寫入8個字節，因此可以分成32頁，24C16一頁最多可以寫入16個字節，因此可以分成128頁。

• 字節寫操作

  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;	//這裏需要看自己使用的芯片設置SDA的IO口爲輸入狀態，我用的是HT45F67芯片，SDA端口設置爲輸入狀態，用於判斷SDA是否接到主機的應答信號
    _delay(2);
    SCL=1;
    _delay(2);
    if(SDA == 1)
    	ack = 0;
    else
      ack = 1;
    SCL=0;
    SDA_CTRL=0;    //此處根據自己所使用的芯片將SDA所在的Io口設置爲輸出狀態
  }
  
  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);
  }

  字節讀操作

• 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);  
  }

  頁寫操作

  Wdata爲輸入數組的首地址，RomAddress爲需要進行存儲的地址，範圍在0~2047之間，cnt爲一次需要寫入的字節個數，建議採用8的倍數的cnt，因爲本函數不採用自動分頁，不是8的倍數會在超出頁寫入最多的字節數之後覆蓋掉原來的數。
  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:連續進行多頁寫操作，需要在WritePage_24LC16B函數後添加150μs以上的延遲，這段時間，24C02內部需要將數據存儲到芯片內部。
  例子:
  D_buffer[8] = {1,2,3,4,5,6,7,8};
  WritePage_24LC16B(D_buffer,0,8);
  _delay(150);        //延遲150μs以及以上
  WritePage_24LC16B(D_buffer,8,8);
  

   

• 頁讀操作

• 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();			//發送完讀地址後，需要應答一下
    }
    *Rdata = ReadByte_24LC16B();
    i2cNoAck_MCU();			//讀取最後一個字節需要非應答
    i2cStop();
    _delay(2000);
  }