16

7618C–AVR–07/08

The API are located at absolute addresses in the USB bootloader firmware and accept specific

registers values as parameters. These parameters are compatible with a C compiler calling con-

vention and thus can be called directly with function pointer declared as in the example below:

The full assembly code for the flash API drivers is given in “Appendix-B” on page 20.

C Code Example

#if (FLASH_END==0x1FFFF) //128K bytes parts

#define

LAST_BOOT_ENTRY

0xFFFE

#elif (FLASH_END==0xFFFF)//64K bytes parts

#define

LAST_BOOT_ENTRY

0x7FFE

#else

#error You must define FLASH_END in bytes.

#endif

void (*boot_flash_page_erase_and_write)(unsigned long adr)=(void (*)(unsigned

long))(LAST_BOOT_ENTRY-12);

U8 (*boot_flash_read_sig) (unsigned long adr)=(U8 (*)(unsigned

long))(LAST_BOOT_ENTRY-10);

U8 (*boot_flash_read_fuse) (unsigned long adr)=(U8 (*)(unsigned

long))(LAST_BOOT_ENTRY-8);

void (*boot_flash_fill_temp_buffer) (unsigned int data,unsigned int adr)=(void

(*)(unsigned int, unsigned int))(LAST_BOOT_ENTRY-6);

void (*boot_flash_prg_page) (unsigned long adr)=(void (*)(unsigned

long))(LAST_BOOT_ENTRY-4);

void (*boot_flash_page_erase) (unsigned long adr)=(void (*)(unsigned

long))(LAST_BOOT_ENTRY-2);

void (*boot_lock_wr_bits) (unsigned char val)=(void (*)(unsigned

char))(LAST_BOOT_ENTRY);

// This function writes 0x55AA @ 0x1200 in the on-flash calling flash drivers located

in USB bootloader

void basic_flash_access(void)

{

unsigned long address;

unsigned int temp16;

temp16=0x55AA;

address=0x12000;

(*boot_flash_fill_temp_buffer)(temp16,address);

(*boot_flash_page_erase)(address);

(*boot_flash_prg_page)(address);

}