Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet

94

SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]

11063K–ATARM–05-Nov-13

The sixth vector, at offset 0x14, contains the size of the image to download. The user must replace this vector with the
user’s own vector. This information is described below.

The value has to be smaller than 24 kbytes. This size is the internal SRAM size minus the stack size used by the ROM
Code at the end of the internal SRAM.

An example of valid vectors follows: 

00

ea000006

B0x20

04

eafffffe

B0x04

08

ea00002f

B_main

0c

eafffffe

B0x0c

10

eafffffe

B0x10

14

00001234

B0x14

<- Code size = 4660 bytes

18

eafffffe

B0x18

This method is the one used on FAT formatted SDCard. The boot program must be a file named “

boot.bin

” written in

the root directory of the file system. Its size must not exceed the maximum size allowed: 24 kbytes (0x6000).

After NAND Flash interface configuration, a reset command is sent to the memory.

The Boot Program first tries to find valid software on a NAND Flash device connected to EBI CS3, with data lines
connected to D0-D7, then on NAND Flash connected to D16-D23. Hardware ECC detection and correction are provided
by the PMECC peripheral (refer to the PMECC section in the datasheet for more information).

The Boot Program is able to retrieve NAND Flash parameters and ECC requirements using two methods as follows: 



the detection of a specific header written at the beginning of the first page of NAND Flash, 

or



through the ONFI parameters for ONFI compliant memories.

31

0

Size of the code to download in bytes