(转)Cortex-M3 (NXP LPC1788)之EEPROM存储器

EEPROM是一种非易失性存储器，主要用于存储相对少量的数据，如存储一些系统的配置信息。通过系统的EEPROM控制模块可以轻松的进行EERPOM的存储控制。

        要正确使用EPPROM需要配置掉电寄存器EEPWRDWN确定EEPROM的工作模式，配置EEPROM时钟分频器寄存器，使EPPROM工作在375KHZ。下面对EPPROM的读和写数据进行介绍。

        EEPROM存储器的访问有三种操作方式：读、写、擦除/编程。对EPPROM中写数据分成两个单独的操作：写和擦除/编程。第一步写操作并不是真正把数据写入EPPROM的存储介质中，而只是更新被称作“页寄存器”的临时数据寄存器。只有执行下一步”擦除/编程“操作才会真正地更新非易失存储器。LPC1788共有4K的片内EPPROM，其中EPPROM的每一页等于页寄存器大小为64Byte，总共有64页。大小正好是64*64=4096Byte=4K。首先我们指定的位数，如8、16或者32位，将数据写入页寄存器，页内的地址偏移由EEPROM地址寄存器的第6位决定。如果需要往页寄存器写入一串数据，写完第一个数据后，页内的偏移地址会自动增加，我们只需把要操作的下一个数据填入EEPROM写数据寄存器即可。当页寄存器的64个字节被写满，必须进行编程操作，将数据写入到EEPROM的存储介质。然后更新页寄存器的偏移地址。

        对于EEPROM的读操作，首先要向地址寄存器写入一个12位的地址，高6位为页的偏移，即我们需要读哪个页寄存器。低6位为页内的偏移，即我们需要读当前页的哪个字节。读操作也可以自动的对地址寄存器做后递增，这样就可以对EEPROM存储器进行连续的操作而无需每次读数据都写入一个新地址。

        下面的程序将信息写入EEPROM后读出通过串口打印显示

#include "LPC1788_REG.h"
#include "uart.h"

#define rEECMD          (*(volatile unsigned*)(0x00200080))
#define rEEADDR         (*(volatile unsigned*)(0x00200084))
#define rEEWDATA        (*(volatile unsigned*)(0x00200088))
#define rEERDATA        (*(volatile unsigned*)(0x0020008C))
#define rEEWSTATE       (*(volatile unsigned*)(0x00200090))
#define rEECLKDIV       (*(volatile unsigned*)(0x00200094))
#define rEEPWRDWN       (*(volatile unsigned*)(0x00200098))

#define rEEINTEN        (*(volatile unsigned*)(0x00200FE4))
#define rEEINTCLR       (*(volatile unsigned*)(0x00200FD8))
#define rEEINTSET       (*(volatile unsigned*)(0x00200FDC))
#define rEEINTSTAT      (*(volatile unsigned*)(0x00200FE0))
#define rEEINTSTATCLR   (*(volatile unsigned*)(0x00200FE8))
#define rEEINTSTATSET   (*(volatile unsigned*)(0x00200FEC))

#define EEPROM_PAGE_SIZE 64
void Init_EEPROM(void);
void Write_EEPROM(unsigned char page_num, unsigned char page_offset, char* data, unsigned int count);
void Read_EEPROM(unsigned char page_num, unsigned char page_offset, char* data, unsigned int count);

char read_buffer[];
char write_buffer[] = {"\n\r\
\t - Name: Nuncle.lee \n\r\
\t - QQ: 23610603 \n\r\
\t - Email: nuncle.lee@gmail.com\n\r"};

int main(void)
{
    Init_Uart2();
    Init_EEPROM();


    Write_EEPROM(0, 0, write_buffer, sizeof(write_buffer));
    Write_EEPROM(sizeof(write_buffer)/64, sizeof(write_buffer)%64, '\0', 1);

    Read_EEPROM(0, 0, read_buffer, sizeof(write_buffer)+1);

    Uart2SendS(read_buffer);

    return 0;
}

void Init_EEPROM(void)
{
    unsigned int val=0;

    rEEPWRDWN = 0;  //不处于掉电模式
    rEECLKDIV = (CCLK/375000)-1;    //设置一个375KHZ的EEPROM时钟

    val  = ((((CCLK / 1000000) * 15) / 1000) + 1);      //配置等待状态时间
    val |= (((((CCLK / 1000000) * 55) / 1000) + 1) << 8);
    val |= (((((CCLK / 1000000) * 35) / 1000) + 1) << 16);
    rEEWSTATE = val;
}
void Write_EEPROM(unsigned char page_num, unsigned char page_offset, char* data, unsigned int count)
{
    unsigned int i;

    rEEADDR = (page_offset&0x3f);   //确定开始写的页内偏移地址
    for(i=0; i<count; i++)
    {
        rEECMD = 0x3;               //8位写操作
        rEEWDATA = *(data+i);
        while(!(rEEINTSTAT & (0x1<<26)));   //等待写操作完成
        page_offset++;

        if(page_offset >= EEPROM_PAGE_SIZE)     //如果当前页写满了64Byte 则启动 编程操作
        {
            rEEINTSTATCLR = 0x1<<28;
            rEEADDR = (page_num&0x3F)<<6;
            rEECMD = 0x6;   //擦除编程
            while(!(rEEINTSTAT & (0x1<<28)));   //等待编程完成

            page_offset = 0;
            page_num++;     //写满一页，准备写下一页
            rEEADDR = 0;    //写满一页，从页的开始写
        }
        elseif(i==count-1)                 //如果要写入EPPROM的数据写完成，启动编程操作
        {
            rEEINTSTATCLR = 0x1<<28;
            rEEADDR = (page_num&0x3F)<<6;
            rEECMD = 0x6;   //擦除编程
            while(!(rEEINTSTAT & (0x1<<28)));
        }
    }
}

void Read_EEPROM(unsigned char page_num, unsigned char page_offset, char* data, unsigned int count)
{
    unsigned int i;
    rEEADDR = (page_num&0x3F)<<6|page_offset&0x3F;      //确定读数据的起始位置，包括页偏移和页内的偏移
    rEECMD = 0x1<<3;                                    //8位读，地址自动递增模式
    for(i=0; i<count; i++)
    {
        while(!(rEEINTSTAT & (0x1<<26)));               //等待上一次读数据完成
        *(data+i) = rEERDATA;
        page_offset++;

        if(page_offset >= EEPROM_PAGE_SIZE)             //如果当前页64Byte读完，准备读下一页
        {
            page_offset = 0;
            page_num++;
            rEEADDR = (page_num&0x3F)<<6|page_offset&0x3F;
            rEECMD = 0x1<<3;
        }
    }
}

#include "LPC1788_REG.h"
#include "uart.h"

#define rEECMD          (*(volatile unsigned*)(0x00200080))
#define rEEADDR         (*(volatile unsigned*)(0x00200084))
#define rEEWDATA        (*(volatile unsigned*)(0x00200088))
#define rEERDATA        (*(volatile unsigned*)(0x0020008C))
#define rEEWSTATE       (*(volatile unsigned*)(0x00200090))
#define rEECLKDIV       (*(volatile unsigned*)(0x00200094))
#define rEEPWRDWN       (*(volatile unsigned*)(0x00200098))

#define rEEINTEN        (*(volatile unsigned*)(0x00200FE4))
#define rEEINTCLR       (*(volatile unsigned*)(0x00200FD8))
#define rEEINTSET       (*(volatile unsigned*)(0x00200FDC))
#define rEEINTSTAT      (*(volatile unsigned*)(0x00200FE0))
#define rEEINTSTATCLR   (*(volatile unsigned*)(0x00200FE8))
#define rEEINTSTATSET   (*(volatile unsigned*)(0x00200FEC))

#define EEPROM_PAGE_SIZE 64
void Init_EEPROM(void);
void Write_EEPROM(unsigned char page_num, unsigned char page_offset, char* data, unsigned int count);
void Read_EEPROM(unsigned char page_num, unsigned char page_offset, char* data, unsigned int count);

char read_buffer[];
char write_buffer[] = {"\n\r\
\t - Name: Nuncle.lee \n\r\
\t - QQ: 23610603 \n\r\
\t - Email: nuncle.lee@gmail.com\n\r"};

int main(void)
{   
    Init_Uart2();
    Init_EEPROM();
    
    
    Write_EEPROM(0, 0, write_buffer, sizeof(write_buffer));
    Write_EEPROM(sizeof(write_buffer)/64, sizeof(write_buffer)%64, '\0', 1);
    
    Read_EEPROM(0, 0, read_buffer, sizeof(write_buffer)+1);
    
    Uart2SendS(read_buffer);

    return 0;
}

void Init_EEPROM(void)
{
    unsigned int val=0;
    
    rEEPWRDWN = 0;  //不处于掉电模式
    rEECLKDIV = (CCLK/375000)-1;    //设置一个375KHZ的EEPROM时钟
    
    val  = ((((CCLK / 1000000) * 15) / 1000) + 1);      //配置等待状态时间
	val |= (((((CCLK / 1000000) * 55) / 1000) + 1) << 8);
	val |= (((((CCLK / 1000000) * 35) / 1000) + 1) << 16);
    rEEWSTATE = val;
}
void Write_EEPROM(unsigned char page_num, unsigned char page_offset, char* data, unsigned int count)
{
    unsigned int i;
    
    rEEADDR = (page_offset&0x3f);   //确定开始写的页内偏移地址
    for(i=0; i<count; i++)
    {
        rEECMD = 0x3;               //8位写操作
        rEEWDATA = *(data+i);
        while(!(rEEINTSTAT & (0x1<<26)));   //等待写操作完成
        page_offset++;
        
        if(page_offset >= EEPROM_PAGE_SIZE)     //如果当前页写满了64Byte 则启动 编程操作
        {
            rEEINTSTATCLR = 0x1<<28;
            rEEADDR = (page_num&0x3F)<<6;
            rEECMD = 0x6;   //擦除编程
            while(!(rEEINTSTAT & (0x1<<28)));   //等待编程完成
            
            page_offset = 0;
            page_num++;     //写满一页，准备写下一页
            rEEADDR = 0;    //写满一页，从页的开始写
        }
        else if(i==count-1)                 //如果要写入EPPROM的数据写完成，启动编程操作
        {
            rEEINTSTATCLR = 0x1<<28;
            rEEADDR = (page_num&0x3F)<<6;
            rEECMD = 0x6;   //擦除编程
            while(!(rEEINTSTAT & (0x1<<28)));
        }
    }
}

void Read_EEPROM(unsigned char page_num, unsigned char page_offset, char* data, unsigned int count)
{
    unsigned int i;
    rEEADDR = (page_num&0x3F)<<6|page_offset&0x3F;      //确定读数据的起始位置，包括页偏移和页内的偏移
    rEECMD = 0x1<<3;                                    //8位读，地址自动递增模式
    for(i=0; i<count; i++)
    {
        while(!(rEEINTSTAT & (0x1<<26)));               //等待上一次读数据完成
        *(data+i) = rEERDATA;
        page_offset++;
        
        if(page_offset >= EEPROM_PAGE_SIZE)             //如果当前页64Byte读完，准备读下一页
        {
            page_offset = 0;
            page_num++;
            rEEADDR = (page_num&0x3F)<<6|page_offset&0x3F;  
            rEECMD = 0x1<<3;
        }
    }
}

 

程序的执行结果如下图

程序中，sizeof关键字计算出字符数组的大小，并不包含字符串的结束标志‘\0’。因此还需在sizeof(write_buffer)的位置写入字符串的结束标志。读取时读sizeof(write_buffer)+1个字节，才能正确的通过串口打印数据。当然，也可以自己指定串口打印字符的个数，而不用字符串结束标志去判断。