DEFINE RESET_ORG and DT Instant Interrupt

[Marcick]

Hi Pedja, thanks for your confirmation.
Yes, I was trying as you say placing the bootloader in the high memory, but then I faced with a "limit" of PBP that requires the library routines (assembly language for high-level commands like HSEROUT) be in memory below 64K.

Here I was asking help to Melabs http://support.melabs.com/forum/picb...modifier-issue

It can works if the code is very basilar, but not for instructions like Hserout, ArrayRead etc (and I need them).

[Marcick]

I'm experimenting this method:

Bootloader code uses DEFINE RESET_ORG 80h and Main program uses DEFINE RESET_ORG 3000h

When the main app need to call bootloader, I disable Interrupt, then remap vectrors, then @ RESET:

	Madr=$EF40: WriteCode 0,Madr		' --> GoTo $80 at address 0	
	Madr=$F000: WriteCode 2,Madr		
	Madr=$EF42: WriteCode 4,Madr		' --> GoTo $84 at address 4
	Madr=$F000: WriteCode 6,Madr		
	Madr=$EF44: WriteCode 8,Madr		' --> GoTo $88 at address 8
	Madr=$F000: WriteCode 10,Madr
	For Madr=12 to 126 step 2			' fill 128 bytes block for PIC18 to complete WriteCode
		WriteCode Madr,$FF
	Next Madr

When the bootloader has finished, same logic above to restore vector at 3000, 3004, 3008, then @ RESET

Not sure if it is a smart solution, but in my mind it should works .....

[pedja089]

Code for bootloader, generally need to be very basic. Then there is little space to make mistake.
My biggest bootloader is around 1,2K, smalest 278B.
I usually use 64K+ to store received HEX. So when I verify download in main code, check checksum, etc. Then I call bootloader, just to copy from 64K+ to 0-64K.
I also used I2C, and SPI flash to store hex.
Comm is handled by main code, sometimes I download hex from FTP, sometimes is over serial, or bluetooth(same as serial)...

[pedja089]

Not good solution at all. Because you need to erase FLASH before writing.
That code need to be in bootloader, as I explained in few post above.
GOTO need to be placed in while assembling, not at runtime.
EDIT:
Try this in bootloader

DEFINE RESET_ORG 80h
@ ORG 0
	@ GOTO 80h
@ ORG 8
	@ GOTO 3008h
@ ORG 4
	@ GOTO 3004h

[Marcick]

Yes, I have to erase just a 128 byte block before.
Well, you are right, but I have not enough resources to use your method. My main program is around 80K, I have not enough space in the external EEprom so I have to manage FTP communication to download the new HEX in the bootloader code. Get a block, flash, Get a block, flash .... no crc controll at all.
I agree there is much risk something goes wrong this way, but if it works I can try remotely update a firmware without having the device back to my lab from the customer as I'm doing now.

Anyway I have space in the GSM module to save a copy of the actual firmware before starting update and manage a restore if some check fails during the update process. It is a heavy bootloader, I know.....