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<>蓝桥杯单片机必备知识-----(11)EEPROM
<>EEPROM
由于EPROM操作的不便，后来出的主板上BIOS ROM芯片大部分都采用EEPROM（Electrically Erasable Programmable
ROM，电可擦除可编程ROM）。EEPROM的擦除不需要借助于其它设备，它是以电子信号来修改其内容的，而且是以Byte为最小修改单位，不必将资料全部洗掉才能写入，彻底摆脱了EPROM
Eraser和编程器的束缚。EEPROM在写入数据时，仍要利用一定的编程电压，此时，只需用厂商提供的专用刷新程序就可以轻而易举地改写内容，所以，它属于双电压芯片。借助于EEPROM芯片的双电压特性，可以使BIOS具有良好的防毒功能，在升级时，把跳线开关打至“on”的位置，即给芯片加上相应的编程电压，就可以方便地升级；平时使用时，则把跳线开关打至“off”的位置，防止CIH类的病毒对BIOS芯片的非法修改。所以，仍有不少主板采用EEPROM作为BIOS芯片并作为自己主板的一大特色。
IIC.H添加
void write_eeprom(unsigned char add,unsigned char val); unsigned char
read_eeprom(unsigned char add);
<>IIC.C中添加
// 写入 void write_eeprom(unsigned char add,unsigned char val) { IIC_Start();
IIC_SendByte(0xa0); IIC_WaitAck(); IIC_SendByte(add); IIC_WaitAck();
IIC_SendByte(val); IIC_WaitAck(); IIC_Stop(); } unsigned char read_eeprom(
unsigned char add) { unsigned char da; IIC_Start(); IIC_SendByte(0xa0);
IIC_WaitAck(); IIC_SendByte(add); IIC_WaitAck(); IIC_Start(); IIC_SendByte(0xa1)
; IIC_WaitAck(); da = IIC_RecByte(); IIC_SendAck(1); IIC_Stop(); return da; }
<>MAIN.C中调用
void delay() //10ms @11.0592MHz { unsigned char i, j; i = 108; j = 145; do {
while (--j); } while (--i); } //数据的读写操作 // write_eeprom(0x00,0x00);
//EEPROM中存储的数据需要进行初始化 reset_cnt = read_eeprom(0x00); //从AT24C02地址0x00中读取数据 delay
(); //延时10ms write_eeprom(0x00,reset_cnt); //向AT24C02地址0x00中写入数据 delay();
<>测试结果：
实现功能：记录开机次数。
<>整个代码粘贴
<>IIC.H
#ifndef _IIC_H #define _IIC_H void IIC_Start(void); void IIC_Stop(void); bit
IIC_WaitAck(void); void IIC_SendAck(bit ackbit); void IIC_SendByte(unsigned char
byt); unsigned char IIC_RecByte(void); void write_eeprom(unsigned char add,
unsigned char val); unsigned char read_eeprom(unsigned char add); #endif
<>IIC.C
#include "reg52.h" #include "intrins.h" #define DELAY_TIME 5 #define
SlaveAddrW 0xA0 #define SlaveAddrR 0xA1 //总线引脚定义 sbit SDA = P2^1; /* 数据线 */
sbit SCL= P2^0; /* 时钟线 */ void IIC_Delay(unsigned char i) { do{_nop_();} while(i
--); } //总线启动条件 void IIC_Start(void) { SDA = 1; SCL = 1; IIC_Delay(DELAY_TIME);
SDA= 0; IIC_Delay(DELAY_TIME); SCL = 0; } //总线停止条件 void IIC_Stop(void) { SDA = 0
; SCL = 1; IIC_Delay(DELAY_TIME); SDA = 1; IIC_Delay(DELAY_TIME); } //发送应答 void
IIC_SendAck(bit ackbit) { SCL = 0; SDA = ackbit; // 0：应答，1：非应答 IIC_Delay(
DELAY_TIME); SCL = 1; IIC_Delay(DELAY_TIME); SCL = 0; SDA = 1; IIC_Delay(
DELAY_TIME); } //等待应答 bit IIC_WaitAck(void) { bit ackbit; SCL = 1; IIC_Delay(
DELAY_TIME); ackbit = SDA; SCL = 0; IIC_Delay(DELAY_TIME); return ackbit; }
//通过I2C总线发送数据 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; }
//从I2C总线上接收数据 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; } // 写入 void write_eeprom(unsigned char add,
unsigned char val) { IIC_Start(); IIC_SendByte(0xa0); IIC_WaitAck();
IIC_SendByte(add); IIC_WaitAck(); IIC_SendByte(val); IIC_WaitAck(); IIC_Stop();
} unsigned char read_eeprom(unsigned char add) { unsigned char da; IIC_Start();
IIC_SendByte(0xa0); IIC_WaitAck(); IIC_SendByte(add); IIC_WaitAck(); IIC_Start()
; IIC_SendByte(0xa1); IIC_WaitAck(); da = IIC_RecByte(); IIC_SendAck(1);
IIC_Stop(); return da; }
<>MAIN.C
#include <stc15f2k60s2.h> #include "iic.h" #define uchar unsigned char #define
uint unsigned char uchar tab[] = {0xc0, 0xf9, 0xa4, 0xb0, 0x99, 0x92, 0x82, 0xf8
, 0x80, 0x90, 0xff}; uchar dspbuf[8] = {10,10,10,10,10,10,10,10}; uchar a1 = 10,
b1= 20,c1 = 0,a2,b2,c2; //uchar s4 = 0,s5 = 0,s8 = 0,s9 = 0; uchar s4 = 0,s5 = 0
,s6 = 0,s7 = 0,s8 = 0,s9 = 0,s10 = 0; uchar s11 = 0,s12 = 0,s13 = 0,s14 = 0,s15
= 0,s16 = 0,s17 = 0,s18 = 0,s19 = 0; void load(); void display(); void read_key(
); void delay() //10ms @11.0592MHz { unsigned char i, j; i = 108; j = 145; do {
while (--j); } while (--i); } void cls() { P2 = (P2 & 0x1f) | 0x80; P0 = 0xff;
P2= 0x1f; P2 = (P2 & 0x1f) | 0xa0; P0 = 0x00; P2 = 0x1f; } void main() { cls();
AUXR= 0xc0; TMOD = 0x00; TL0 = 0xcd; TH0 = 0xd4; TR0 = 1; ET0 = 1; EA = 1; c2 =
read_eeprom(0x04); delay(); c1 = c2 + 1; write_eeprom(0x04,c1); delay(); dspbuf[
4] = c2 / 10; dspbuf[5] = c2 % 10; while(1){} } void time0() interrupt 1 {
display(); } void display() { static unsigned char dspcom = 0; P2 = (P2 & 0x1f)
| 0xe0; P0 = 0xff; P2 = 0x1f; P2 = (P2 & 0x1f) | 0xc0; P0 = 1 << dspcom; P2 =
0x1f; P2 = (P2 & 0x1f) | 0xe0; P0 = tab[dspbuf[dspcom]]; P2 = 0x1f; if(++dspcom
== 8) dspcom = 0; }