/* 實驗四十二 IIC總線24C02讀寫 */
/* C51 */


#include <reg51.h>
#include <intrins.h>

/* **********************************************************
  24C01/02 為IIC總線EEPROM存儲器, 容量為1k位(128 * 8)
************************************************************/


/* **********************************************************
   EEPROM控制字節格式：
   [1, 0, 1, 0, A2, A1, A0, (R/W)], 其中R/W=1讀,R/W=0寫;
   由于實驗儀上的AT24C01A(AT24C02) 的A2/A1/A0全部接地,
   所以讀/寫控制字分別為：0xa1/0xa0
************************************************************/
#define WriteDeviceAddress 0xa0
#define ReadDeviceAddress 0xa1

/******************IIC器件驅動引腳定義**********************/
sbit SCL = P1^0;
sbit SDA = P1^1;

/***********************簡單延時****************************/
void DelayMs(unsigned int number) {
  unsigned char temp = 112;
  while(number--!=0) {
    while(temp--!=0) {
    }
  }
}

/*********************啟動IIC總線***************************/
void Start() {
  SDA = 1;
  SCL = 1;
  SDA = 0;
  SCL = 0;
}

/*********************停止IIC總線***************************/
void Stop() {
  SCL = 0;
  SDA = 0;
  SCL = 1;
  SDA = 1;
}

/***********************請求相應****************************/
void Ack() {
  SDA = 0;
  SCL = 1;
  SCL = 0;
  SDA = 1;
}

/*******************不對IIC總線產生應答*********************/
void NoAck() {
  SDA = 1;
  SCL = 1;
  SCL = 0;
}

/**********************檢查應答位***************************/
bit TestAck() {
  SDA = 1;
  SCL = 1;
  CY = SDA;
  SCL = 0;
  return(CY);
}

/********************向IIC總線寫數據************************/
bit Write8Bit(unsigned char input) {
  unsigned char temp;
  for(temp = 8; temp != 0; temp--) {
    SDA = (bit)(input&0x80);
    SCL = 1;
    SCL = 0;
    input = input<<1;
  }
  return(0);
}


/****************從IIC總線上讀數據子程序********************/
unsigned char Read8Bit() {
  unsigned char temp, rbyte=0;
  for(temp=8;temp!=0;temp--) {
    SCL=1;
    rbyte=rbyte<<1;
    rbyte=rbyte|((unsigned char)(SDA));
    SCL=0;
  }
  return(rbyte);
}

/*******************向EEPROM中寫入數據塊********************/
void AT24C02WriteBlock(unsigned char *Wdata, unsigned char RomAddress, unsigned char number) {
  if(number > 8)
    number %= 8; /*對于24C02, 一個頁為8字節，所以最大的塊寫操作字節數為8*/
  Start();
  Write8Bit(WriteDeviceAddress);
  TestAck();
  Write8Bit(RomAddress);
  TestAck();
  for(;number!=0;number--) {
    Write8Bit(*Wdata);
    TestAck();
    Wdata++;
  }
  Stop();
  DelayMs(10);
}

/**************從EEPROM中讀出數據塊到指定RAM中**************/
void AT24C02ReadBlock(unsigned char *RamAddress, unsigned char RomAddress, unsigned char bytes) {
  EA = 0;
  Start();
  Write8Bit(WriteDeviceAddress);
  TestAck();
  Write8Bit(RomAddress);
  TestAck();
  Start();
  Write8Bit(ReadDeviceAddress);
  TestAck();
  while(bytes!=1) {
    *RamAddress = Read8Bit();
    Ack();
    RamAddress++;
    bytes--;
  }
  *RamAddress = Read8Bit();
  NoAck();
  Stop();
}


/*****************向EEPROM中寫入單字節數據******************/
void AT24c02WriteByte(unsigned char WriteData, unsigned char RomAddress) {
  Start();
  Write8Bit(WriteDeviceAddress);
  TestAck();
  Write8Bit(RomAddress);
  TestAck();
  Write8Bit(WriteData);
  TestAck();
  Stop();
  DelayMs(10);
}

/************從EEPROM中讀出單字節數據到指定RAM中************/
unsigned char AT24c02ReadByte(unsigned char RomAddress) {
  unsigned char ReadData;
  Start();
  Write8Bit(WriteDeviceAddress);
  TestAck();
  Write8Bit(RomAddress);
  TestAck();

  Start();
  Write8Bit(ReadDeviceAddress);
  TestAck();

  ReadData = Read8Bit();
  NoAck();
  Stop();
  return(ReadData);
}



void main(void)
{
  unsigned char i;
  unsigned char WriteBuff[8], ReadBuff[8];

  /* 讀寫緩沖初始化 */
  for(i = 0; i < 8; i++) {
    WriteBuff[i] = 0x55 + i;
    ReadBuff[i] = 0xff;
  }

  /* 從地址0開始按字節方式寫入8個數據'0' */
  for(i = 0; i < 8; i++) {
    AT24c02WriteByte(0, i);
  }

  /* 按字節方式讀出數據 */
  for(i = 0; i < 8; i++) {
    ReadBuff[i] = AT24c02ReadByte(i);
  }

  /* 按寫Page方式從地址0開始寫入WriteBuff指向的8個數據 */
  AT24C02WriteBlock(WriteBuff, 0x00, 8);

  /* 按連續讀取方式讀出從地址0開始的8個數據 */
  AT24C02ReadBlock(ReadBuff, 0x00, 8);
  while(1);

}