stm8s development (nine) use of EEPROM: use EEPROM to store data!

　　EEPROM is a memory often used in microcontroller application systems. It is mainly used to save some data that needs to remain unchanged after power failure. In previous microcontroller systems, an EEPROM chip was usually added outside the microcontroller. This method not only increases costs, but also reduces reliability. Now, many microcontroller companies have launched microcontrollers with integrated small-capacity EEPROM, which is convenient to use, reduces costs, and improves reliability.

　　The STM8 microcontroller chip also integrates EEPROM, with a capacity ranging from 640 bytes to 2K bytes. The most unique feature is that in the STM8 microcontroller, access to the EEPROM is just like regular RAM, which is very convenient. The address space of the EEPROM is uniformly addressed with the memory, starting from 004000H, and the size depends on the different chip models.

　　For ease of management, define the address of the EEPROM

　　#define EP_HEADER_ADDR 0x4000

　　Operating the EEPROM requires initialization, which is FLASH unlocking. Unlocking requires two keys, and the order cannot be reversed.

　　void EEPROM_init(void)

　　{

　　do

　　{

　　FLASH_CR1=0x00;

　　FLASH_CR2=0x00;

　　FLASH_NCR2=0xFF;

　　FLASH_DUKR = 0xAE; // Write the first key

　　FLASH_DUKR = 0x56; // Write the second key

　　} while((FLASH_IAPSR & 0x08) == 0); // If unlocking fails, try again

　　}

　　There is also a locking function. Generally speaking, lock protection is required after operating the EEPROM.

　　void EEPROM_lock(void)

　　{

　　FLASH_IAPSR=(u8)(~0x08); //Relock

　　}

　　Next are two basic operations of reading and writing.

　　//Write a data to the specified address of EEPROM addr: relative address dat: data

　　void EEPROM_write(unsigned char addr, unsigned char dat)

　　{

　　unsigned char *p;

　　p=(unsigned char *)(EP_HEADER_ADDR + addr);

　　*p=dat;

　　while(!(FLASH_IAPSR&0x04)); //Wait for write operation to succeed

　　}

　　//Read a data from the specified address of EEPROM addr: relative address

　　unsigned char EEPROM_read(unsigned char addr)

　　{

　　unsigned char *p;

　　p=(unsigned char *)(EP_HEADER_ADDR + addr);

　　return *p;

　　}

　　The address given here is an absolute address. There is an offset address operation in the function (offset 4000H).

　　Fried chicken is simple, isn’t it?

　　Introduction to EEPROM and FLASH: http://blog.csdn.net/yuanlulu/article/details/6163106

　　Attached is the project of stm8s in IAR environment, including the initialization code of on-chip hardware such as SPI, IIC, PWM, AWU, USART, EEPROM, etc.

　　http://download.csdn.NET/detail/devintt/9454188