AVR Freaks

Umm ok so I am getting a weird side-effect of adding -Wl,-section-start=.text=0x7000 to the linker...

It will now only once fire the ISR(USART_RX_vect){} interrupt.

I have commented out all code  to do with the bootloader to the point all the interrupt does is toggle an LED.

If I remove -Wl,-section-start=.text=0x7000 the interupt goes of everytime i hit a key in putty when the compile flag is set it only goes off once? 

From reading the data sheet I think it is something to do with:

Notes: 1. When the BOOTRST Fuse is programmed, the device will jump to the Boot Loader address at reset, see ”Boot Loader Support
– Read-While-Write Self-Programming, ATmega88PA, ATmega168PA and ATmega328P” on page 277.
2. When the IVSEL bit in MCUCR is set, Interrupt Vectors will be moved to the start of the Boot Flash Section. The address of
each Interrupt Vector will then be the address in this table added to the start address of the Boot Flash Section.

So the vector should now be 0x7000 + 0x024(RX complete interupt)... But I don't understand how to refelct that in my program.

ISR(0x7024) gives a compile error.

So I solved this was super easy in the end just combing through the data sheet Doh.

Just run :

void Move_interrupts(void)
{
/* Enable change of Interrupt Vectors */
MCUCR = (1<<IVCE);
/* Move interrupts to Boot Flash section */
MCUCR = (1<<IVSEL);
}

Yeah im not actually using interrupts from within the bootloader code I have written :)

Sooo I have found that using -Wl,-section-start=.text=0x7000 is putting my whole program in the bootloader section hence why I needed to change my ISR locations... this is not ideal. I really just want the function from my code :

void boot_program_page(uint32_t page, uint8_t *buf){

to be in the bootloader section so it is able to write my image file to program memory then return to the normal program. How do I tell the compiler/ linker to do this?

OK how do I assign a specific section to the function? i though i had by doing :

void boot_program_page (uint32_t page, volatile uint8_t *buf) BOOTLOADER_SECTION;

/*image start page should always be 0x2000 giving:
 * 0x0000 -> 0x1FFF Application memory (16KB)
 * 0x2000 -> 0x3680 Image Data (11520 Bytes)
 * 0x3681 -> 0x37FF Free space
 * 0x3800 -> 0x4000 BootLoader (4KB)
 *
 * NOTE page is a byte address the above example uses word addressing.
 * Requires compiler flag: -Wl,-section-start=.text=0x7000
*/
void boot_program_page(uint32_t page, volatile uint8_t *buf){
	uint16_t i;
	uint8_t sreg;
	
	//disable interupts
	sreg = SREG;
	cli();
	
	eeprom_busy_wait ();//ensure eeprom is not busy as SPM cannot operate while an eeprom operation is taking place.
	boot_page_erase (page);
	boot_spm_busy_wait (); // Wait until the memory is erased.
	
	for (i=0; i<SPM_PAGESIZE; i+=2)
	{
		// Set up little-endian word.
		uint16_t w = *buf++;
		w += (*buf++) << 8;
		boot_page_fill (page + i, w);
	}
	boot_page_write (page); // Store buffer in flash page.
	boot_spm_busy_wait(); // Wait until the memory is written.
	// Reenable RWW-section again. We need this if we want to jump back
	// to the application after bootloading.
	boot_rww_enable ();
	// Re-enable interrupts (if they were ever enabled).
	SREG = sreg;
	//sei();///Maybe remove from here
}

-Wl,-section-start=.text=0x7000 is what I am currently giving the linker, I am assuming this is not actually what I want