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

#define	OP_READ	0xa1		// 器件地址以及讀取操作
#define	OP_WRITE 0xa0		// 器件地址以及寫入操作
#define	MAX_ADDR 0x7f		// AT24C02最大地址

unsigned char code dis_code[] = {0x7e,0xbd,0xdb,0xe7,0xdb,0xbd,0x7e,0xff};
				// 寫入到AT24C01的數據串

sbit SDA = P3^4;
sbit SCL = P3^3;


void start();
void stop();
unsigned char shin();
bit shout(unsigned char write_data);
unsigned char read_random(unsigned char random_addr);
void write_byte( unsigned char addr, unsigned char write_data);
void fill_byte(unsigned char fill_data);
void delayms(unsigned char ms);

main(void)
{
	unsigned char i;
	SDA = 1;
	SCL = 1;
	fill_byte(0xff);		// 全部填充0xff

	for(i = 0 ; i < 8; i++)		//寫入顯示代碼到AT24Cxx
	{
		write_byte(i, dis_code[i]);
	}

	i = 0;
	while(1)
	{

		P0 = read_random(i);	// 循環讀取24Cxx內容，并輸出到P0口
		i++;
		i &= 0x07;		// 循環讀取范圍為0x00～0x07
		delayms(250);
	}
}

void start()
// 開始位
{
	SDA = 1;
	SCL = 1;
	_nop_();
	_nop_();
	SDA = 0;
	_nop_();
	_nop_();
	_nop_();
	_nop_();
	SCL = 0;
}

void stop()
// 停止位
{
	SDA = 0;
	_nop_();
	_nop_();
	SCL = 1;
	_nop_();
	_nop_();
	_nop_();
	_nop_();
	SDA = 1;
}

unsigned char shin()
// 從AT24Cxx移入數據到MCU
{
	unsigned char i,read_data;
	for(i = 0; i < 8; i++)
	{
		SCL = 1;
		read_data <<= 1;
		read_data |= (unsigned char)SDA;
		SCL = 0;
	}
	return(read_data);
}
bit shout(unsigned char write_data)
// 從MCU移出數據到AT24Cxx
{
	unsigned char i;
	bit ack_bit;
	for(i = 0; i < 8; i++)		// 循環移入8個位
	{
		SDA = (bit)(write_data & 0x80);
		_nop_();
		SCL = 1;
		_nop_();
		_nop_();
		SCL = 0;
		write_data <<= 1;
	}
	SDA = 1;			// 讀取應答
	_nop_();
	_nop_();
	SCL = 1;
	_nop_();
	_nop_();
	_nop_();
	_nop_();
	ack_bit = SDA;
	SCL = 0;
	return ack_bit;			// 返回AT24Cxx應答位
}

void write_byte(unsigned char addr, unsigned char write_data)
// 在指定地址addr處寫入數據write_data
{
	start();
	shout(OP_WRITE);
	shout(addr);
	shout(write_data);
	stop();
	delayms(10);		// 寫入周期
}

void fill_byte(unsigned char fill_data)
// 填充數據fill_data到EEPROM內
{
	unsigned char i;
	for(i = 0; i < MAX_ADDR; i++)
	{
		write_byte(i, fill_data);
	}

}

unsigned char read_current()
// 在當前地址讀取
{
	unsigned char read_data;
	start();
	shout(OP_READ);
	read_data = shin();
	stop();
	return read_data;
}

unsigned char read_random(unsigned char random_addr)
// 在指定地址讀取
{
	start();
	shout(OP_WRITE);
	shout(random_addr);
	return(read_current());
}

void delayms(unsigned char ms)	
// 延時子程序
{
	unsigned char i;
	while(ms--)
	{
		for(i = 0; i < 120; i++);
	}
}