AT24C02是一个2K位串行CMOS E2PROM, 内部含有256个8位字节,CATALYST公司的先进CMOS技术实质上减少了器件的功耗。AT24C02有一个16字节页写缓冲器。该器件通过IIC总线接口进行操作,有一个专门的写保护功能。用于存储数据,掉电也不丢失数据。
首先来看蓝桥杯单片机开发板上的原理图部分。
A0-A3:用于调节IIC的硬件地址,用于多个EEPROM连接。
SCL,SDA:IIC时钟线和数据线。
WP:写保护位,高电平时只可读。
接下来看AT24C02的数据手册
由于A0-A2接地,所以地址为0XA0,最后一位用于控制写和读。由于是256个8位字节,所以直接指定要写到哪个字节即可。
按页连续写时序图
下面来看写程序
void IIC_write(uchar hw_address,uchar reg_address,uchar num)
{
IIC_Start();
IIC_SendByte(hw_address&0xfe);
IIC_WaitAck();
IIC_SendByte(reg_address);
IIC_WaitAck();
IIC_SendByte(num);
IIC_WaitAck();
IIC_Stop();
}
#define AT24C02_address 0xA0
使用:IIC_write(AT24C02_address,0,11)
在第零个字节处写11
//连续写
void IIC_write(uchar hw_address,uchar reg_address,uchar num)
{
IIC_Start();
IIC_SendByte(hw_address&0xfe);
IIC_WaitAck();
IIC_SendByte(reg_address);
IIC_WaitAck();
IIC_SendByte(num);
IIC_WaitAck();
IIC_SendByte(num+2);
IIC_WaitAck();
IIC_Stop();
}
//在0写11,在1写13
按页次序读时序
然后看读程序
uchar IIC_read(uchar hw_address,uchar reg_address)
{
uchar num;
IIC_Start();
IIC_SendByte(hw_address&0xfe);
IIC_WaitAck();
IIC_SendByte(reg_address);
IIC_WaitAck();
IIC_Stop();
IIC_Start();
IIC_SendByte(hw_address|0x01);
IIC_WaitAck();
num=IIC_RecByte();
IIC_WaitAck();
IIC_Stop();
return num;
}
#define AT24C02_address 0x90
使用:date=IIC_read(AT24C02_address,0)
读零号字节
//连续读
void IIC_read(uchar hw_address,uchar reg_address)
{
uchar num;
IIC_Start();
IIC_SendByte(hw_address&0xfe);
IIC_WaitAck();
IIC_SendByte(reg_address);
IIC_WaitAck();
IIC_Stop();
IIC_Start();
IIC_SendByte(hw_address|0x01);
IIC_WaitAck();
num1=IIC_RecByte();
IIC_SendAck(0);
num2=IIC_RecByte();
IIC_Stop();
}
//读取第0个字节和第1个字节数据
最后设计一个使用EEPROM保存DS1302的时间,让每次掉电时间保存起来,重新上电从上一次掉电时间开始。代码如下:
#include <STC15F2K60S2.H>
#include "intrins.h"
sbit SDA = P2^1; /* 数据线 */
sbit SCL = P2^0; /* 时钟线 */
sbit SCK=P1^7;
sbit IO=P2^3;
sbit RST = P1^3; // DS1302复位
#define uchar unsigned char
#define uint unsigned int
#define DELAY_TIME 40
#define AT24C02_address 0xA0
bit IIC_WaitAck(void);
void IIC_SendAck(bit ackbit);
void IIC_Stop(void);
void IIC_Start(void);
void IIC_Delay(unsigned char i);
unsigned char IIC_RecByte(void);
void IIC_SendByte(unsigned char byt);
void IIC_read(uchar hw_address,uchar reg_address);
void IIC_write(uchar hw_address,uchar reg_address);
unsigned char Read_Ds1302_Byte ( unsigned char address );
void Write_Ds1302_Byte( unsigned char address,unsigned char dat );
void Write_Ds1302(unsigned char temp);
void get_time(void);
void ds1302_init(void);
void init(void);
void SMG_output(void);
void Delay1ms(void);
uchar tab[]={
0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,\
0x40,0x79,0x24,0x30,0x19,0x12,0x02,0x78,0x00,0x10,0xff,0xbf};
uchar SMG[8]={
20,20,20,20,20,20,20,20};
uint move=0;
uchar time[7]={
0,0,0,0,0,0,0};
void main(void)
{
init();
// IIC_write(AT24C02_address,0x00);Delay1ms();Delay1ms();Delay1ms();Delay1ms();Delay1ms();
IIC_read(AT24C02_address,0x00);
ds1302_init();
while(1)
{
get_time();
IIC_write(AT24C02_address,0x00);
SMG[0]=time[2]/10;SMG[1]=time[2]%10;
SMG[3]=time[1]/10;SMG[4]=time[1]%10;
SMG[6]=time[0]/10;SMG[7]=time[0]%10;
SMG_output();
}
}
void IIC_write(uchar hw_address,uchar reg_address)
{
uchar i;
IIC_Start();
IIC_SendByte(hw_address&0xfe);
IIC_WaitAck();
IIC_SendByte(reg_address);
IIC_WaitAck();
for(i=0;i<3;i++)
{
IIC_SendByte(time[i]);
IIC_WaitAck();
}
IIC_Stop();
}
void IIC_read(uchar hw_address,uchar reg_address)
{
uchar i;
IIC_Start();
IIC_SendByte(hw_address&0xfe);
IIC_WaitAck();
IIC_SendByte(reg_address);
IIC_WaitAck();
IIC_Stop();
IIC_Start();
IIC_SendByte(hw_address|0x01);
IIC_WaitAck();
for(i=0;i<3;i++)
{
time[i]=IIC_RecByte();
IIC_SendAck(0);
}
IIC_Stop();
}
void ds1302_init(void)
{
uchar i,j=0x80;
Write_Ds1302_Byte(0x8e,0x00);
for(i=0;i<7;i++)
{
Write_Ds1302_Byte(j,time[i]);
j +=2;
}
Write_Ds1302_Byte(0x8e,0x80);
}
void get_time(void)
{
uchar i,j=0x81;
Write_Ds1302_Byte(0x8e,0x00);
for(i=0;i<7;i++)
{
time[i]=Read_Ds1302_Byte(j);
j +=2;
}
Write_Ds1302_Byte(0x8e,0x80);
}
void Write_Ds1302(unsigned char temp)
{
unsigned char i;
for (i=0;i<8;i++)
{
SCK=0;
IO=temp&0x01;
temp>>=1;
SCK=1;
}
}
void Write_Ds1302_Byte( unsigned char address,unsigned char dat )
{
RST=0; _nop_();
SCK=0; _nop_();
RST=1; _nop_();
Write_Ds1302(address);
Write_Ds1302(((dat/10)<<4)|(dat%10));
RST=0;
}
unsigned char Read_Ds1302_Byte ( unsigned char address )
{
unsigned char i,temp=0x00;
RST=0; _nop_();
SCK=0; _nop_();
RST=1; _nop_();
Write_Ds1302(address);
for (i=0;i<8;i++)
{
SCK=0;
temp>>=1;
if(IO)
temp|=0x80;
SCK=1;
}
RST=0; _nop_();
SCK=0; _nop_();
SCK=1; _nop_();
IO=0; _nop_();
IO=1; _nop_();
return (((temp/16)*10)+(temp%16));
}
//
void IIC_Delay(unsigned char i)
{
do{
_nop_();}
while(i--);
}
//
void IIC_Start(void)
{
SDA = 1;
SCL = 1;
IIC_Delay(DELAY_TIME);
SDA = 0;
IIC_Delay(DELAY_TIME);
SCL = 0;
}
//
void IIC_Stop(void)
{
SDA = 0;
SCL = 1;
IIC_Delay(DELAY_TIME);
SDA = 1;
IIC_Delay(DELAY_TIME);
}
//
void IIC_SendAck(bit ackbit)
{
SCL = 0;
SDA = ackbit;
IIC_Delay(DELAY_TIME);
SCL = 1;
IIC_Delay(DELAY_TIME);
SCL = 0;
SDA = 1;
IIC_Delay(DELAY_TIME);
}
//
bit IIC_WaitAck(void)
{
bit ackbit;
SCL = 1;
IIC_Delay(DELAY_TIME);
ackbit = SDA;
SCL = 0;
IIC_Delay(DELAY_TIME);
return ackbit;
}
//
void IIC_SendByte(unsigned char byt)
{
unsigned char i;
for(i=0; i<8; i++)
{
SCL = 0;
IIC_Delay(DELAY_TIME);
if(byt & 0x80) SDA = 1;
else SDA = 0;
IIC_Delay(DELAY_TIME);
SCL = 1;
byt <<= 1;
IIC_Delay(DELAY_TIME);
}
SCL = 0;
}
//
unsigned char IIC_RecByte(void)
{
unsigned char i, da;
for(i=0; i<8; i++)
{
SCL = 1;
IIC_Delay(DELAY_TIME);
da <<= 1;
if(SDA) da |= 1;
SCL = 0;
IIC_Delay(DELAY_TIME);
}
return da;
}
void init(void)
{
P2=(P2&0X1F)|0XA0;
P0=0X00;
P2=(P2&0X1F)|0X80;
P0=0XFF;
P2=(P2&0X1F)|0XC0;
P0=0XFF;
P2=(P2&0X1F)|0XE0;
P0=0XFF;
}
void SMG_output(void)
{
uchar i;
for(i=0;i<8;i++)
{
P2=(P2&0X1F)|0XC0;
P0=(1 << i);
P2=(P2&0X1F)|0XE0;
P0=tab[SMG[i]];
Delay1ms();
}
P2=(P2&0X1F)|0XC0;
P0=0XFF;
P2=(P2&0X1F)|0XE0;
P0=0XFF;
}
void Delay1ms(void) //@11.0592MHz
{
unsigned char i, j;
_nop_();
_nop_();
_nop_();
i = 11;
j = 190;
do
{
while (--j);
} while (--i);
}
值得注意是,第一次需要进行一次写操作,然后注释掉重新下载即可。
效果如下
不懂可以评论和私信。