Atmel ARM-Based Evaluation Kit for SAM4S16C, 32-Bit ARM® Cortex® Microcontroller ATSAM4S-WPIR-RD ATSAM4S-WPIR-RD Data Sheet

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SAM4S Series [DATASHEET]

Atmel-11100G-ATARM-SAM4S-Datasheet_27-May-14

The IAP feature is a function located in ROM that can be called by any software application.
When called, this function sends the desired FLASH command to the EEFC and waits for the Flash to be ready 

(looping while the FRDY bit is not set in the MC_FSR register).
Since this function is executed from ROM, this allows Flash programming (such as sector write) to be done by 

code running in Flash.
The IAP function entry point is retrieved by reading the NMI vector in ROM (0x00800008).
This function takes two arguments in parameter: the EFC number and the command to be sent to the EEFC.
This function returns the value of the MC_FSR register.
IAP software code example:

(unsigned int) (*IAP_Function)(unsigned long);

void main (void){

unsigned long FlashSectorNum = 200; // 

unsigned long flash_cmd = 0;

unsigned long flash_status = 0;

unsigned long EFCIndex = 0; // 0:EEFC0, 1: EEFC1

/* Initialize the function pointer (retrieve function address from NMI vector) 

*/

IAP_Function = ((unsigned long) (*)(unsigned long)) 

0x00800008;

/* Send your data to the sector here */

/* build the command to send to EEFC */

flash_cmd =  (0x5A << 24) | (FlashSectorNum << 8) | 

AT91C_MC_FCMD_EWP;

/* Call the IAP function with appropriate command */

             

flash_status = IAP_Function (EFCIndex, flash_cmd);

}