MCF52233_CFM——Coldfire Flash Module

　　Coldfire的CFM功能是把它的flash当作EEPROM来用。使用起来还是很方便的，只要完成几个小的功能函数就行了：

　　第一个是CFM的初始化CFM_init()，完成时钟的设置；

　　第二个是页擦除CFM_Page_eraser()，完成一页的擦除工作，Coldfire的256K flash被分成128页，每2K为1页，只有在擦除后才能正确地向一个地址中写入数据；

　　第三个是CFM_Write(),完成向某地址写入数据的功能，Coldfire的CFM是按字操作的，以4B为一个最小单位。

　　CFM有5个CMD：Blank Check 、Pageerase verify、 Word program 、Page erase 、Mass erase但只要其中Word program 、Page erase 两个就能满足一般的使用了。

　　在使用CFM功能时对它的地址这块可能会有些迷惑，这里简单介绍下：MCF52233有256K的flash，默认情况下起始地址是0x44000000(#define CFM_IPS_FLASH_ADDR 0x44000000)，我们不能在存有程序的地方擦、写数据，最简单的办法就是在flash的最后面操作，这样就不要考虑烧进去的程序结束的位置了。起始地址加上256K得到最后一个存储单元的地址即#define FLASH_END_ADDRESS　CFM_IPS_FLASH_ADDR+0x40000)，我们就从FLASH_END_ADDRESS 开始往前写我们的数据。

　　最后一点就是怎样读我们写的数据，其实非常简单，用read_data=(*(uint32 *)(address))就将address处的数据赋给了read_data；同样，在写数据的时候会用到(*(uint32*)(address))=write_data来将数据写到address地址处。

程序如下：

/*CFM初始化*/

uint8 CFM_init(unsigned long FlashClk)
{
unsigned char fclk_val;

if ((MCF_CFM_CFMCLKD & MCF_CFM_CFMCLKD_DIVLD)==0)
{
//Initialize FCLKDIV register to ensure we can program/erase */
fclk_val = (unsigned char)(FlashClk/8/200-1);
MCF_CFM_CFMCLKD |= MCF_CFM_CFMCLKD_DIV(fclk_val)

　　　　　　　　　　　 | MCF_CFM_CFMCLKD_PRDIV8;
}

//Disable all protection (if LOCK not set)*/
MCF_CFM_CFMPROT=0;

//Clear any errors
MCF_CFM_CFMUSTAT |=MCF_CFM_CFMUSTAT_PVIOL

　　　　　　　　　　　　|MCF_CFM_CFMUSTAT_ACCERR;
return 0;
}

/*页擦除*/

uint8 CFM_page_erase(unsigned char page)
{
while (!(MCF_CFM_CFMUSTAT&MCF_CFM_CFMUSTAT_CBEIF));

//Clear any errors
MCF_CFM_CFMUSTAT =MCF_CFM_CFMUSTAT_PVIOL

　　　　　　　　　　　　|MCF_CFM_CFMUSTAT_ACCERR;

(*(vuint32*)(FLASH_START_ADDRESS+page*0x800))=1;

MCF_CFM_CFMCMD=MCF_CFM_CFMCMD_PAGE_ERASE;
//Launch CMD
MCF_CFM_CFMUSTAT=MCF_CFM_CFMUSTAT_CBEIF;
//wait for complete and check result
while(!(MCF_CFM_CFMUSTAT&MCF_CFM_CFMUSTAT_CCIF))
{
if(MCF_CFM_CFMUSTAT&MCF_CFM_CFMUSTAT_PVIOL) return 0;
}
if(MCF_CFM_CFMUSTAT&MCF_CFM_CFMUSTAT_ACCERR) return 0;
return 1;
}

/*flash写操作*/

uint8 CFM_write(unsigned int address ,unsigned int data)
{
if((uint32)address&0x00000001) return 0;
//Clear any errors
MCF_CFM_CFMUSTAT=MCF_CFM_CFMUSTAT_PVIOL

　　　　　　　　　　　|MCF_CFM_CFMUSTAT_ACCERR;

(*(vuint32*)(FLASH_END_ADDRESS-4-address))=data;
//launch command
MCF_CFM_CFMCMD=MCF_CFM_CFMCMD_WORD_PROGRAM;
MCF_CFM_CFMUSTAT=MCF_CFM_CFMUSTAT_CBEIF;
//wait for complete and check result
while(!(MCF_CFM_CFMUSTAT&MCF_CFM_CFMUSTAT_CCIF))
{
if(MCF_CFM_CFMUSTAT&MCF_CFM_CFMUSTAT_PVIOL) return 0;
}
if(MCF_CFM_CFMUSTAT&MCF_CFM_CFMUSTAT_ACCERR) return 0;
return 1;
}