RM0319 datasheet(43/368 Pages) STMICROELECTRONICS

43 / 368 page

RM0319

BootROM

Doc ID 022640 Rev 3

43/368

BootROM code reads the device ID code and looks for it in a table which contains all

supported device codes. Then, it fills a device description structure for page_size,

block_size, memory size and spare command according to this ID code.

After that, it searches for X-Loader in the first page of every block of the Flash starting from

the 1st block to the 4th block. Before reading the block, it checks the sanity by reading the

1st word of the spare area of each block which should be 0xFF. If it not 0xFF, it skips to the

next block.

Read the whole page in a buffer (buffer size equals page size) and search for X-Loader.

If found, return to the start address.

Find the transfer size from the header. Calculate the number of pages and start reading

the pages from the Flash copying them into the shadow memory.

Authenticate X-Loader. If authenticated, jump to the start address, otherwise jump to

USB boot.

While reading, check ECC for every page, read ECC from the NAND memory spare

area and from the FSMC controller. If there is an error of 1 bit, fix it, otherwise you will

get a “Boot failed” message.

RM0319 数据表(PDF) 43 Page - STMicroelectronics