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Bootloader int_global information

 
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niccolo.calandri



Joined: 20 May 2016
Posts: 10

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Bootloader int_global information
PostPosted: Thu Jun 15, 2017 1:45 am     Reply with quote

I'm triying to modify the BOOTLOADER in order to update the firmware from an External EEPROM, for OTA.

I almost understand all the CCSC example except for this sentence:
Code:

#int_global                                                                     
void isr(void) {
   jump_to_isr(LOADER_END+5*(getenv("BITS_PER_INSTRUCTION")/8));   //65527 + 10
}

Someone can explain the interrupt?
Ttelmah



Joined: 11 Mar 2010
Posts: 19496

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PostPosted: Thu Jun 15, 2017 3:27 am     Reply with quote

It's the 'revectorer' (created word...). Very Happy

The bootloader sits at the bottom of memory (it has to in order to be called on boot). Problem is that the interrupts call one or two locations immediately above this (one for a PIC16, two for a PIC18). The 'jump_to_isr()' instruction, is a special one, that automatically inserts the jump(s) (both if necessary), 'up' to where the boot code resides in your loaded program.

So it 'revectors' the one or two interrupt calls up to the loaded code. Does nothing else.
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