Issues with a bootloader

[Scampy]

I wiped the PIC and loaded the bootloader, read back a screen dump and showed FF for all blocks apart from the 1st four. The PC app fond the pic and uploaded the main code - You can see that the first 4 blocks remained the same so I'm guessing it didn't overwrite the bootloader (see the diagram attached)

My PicFlash application has tick boxes for code protect sections of PIC memory - is it worth enabling this for 0x00 ??



Sorry guys the forum resizes the image - here's a link to the full sized one http://www.micro-heli.co.uk/screendump.png

[HenrikOlsson]

Scampy,
Try adding

DEFINE LOADER_USED 1

And see if that makes it any better.

/Henrik.

[Art]

Surely a boot loader can’t be written in a few instructions...
Have you scrolled right down the bottom of your hex file when only the boot loader is loaded?
I think it would be written to the last locations it could fit.

[Scampy]

Art, I think the bootloader contains the "goto" section at the start, and then the actual loader is at the end of the code space as shown below and confirmed in the attachment.



@Henrik, Line added to the main code - thanks

[Scampy]

It's still flakey, but seems to work 8 out of 10 times !

Cheers guys

[Art]

If the boot loader can write your program over serial the pic must support program memory read/write.
So you should be able to check if the loader exists with your own pic program.
If you think you're overwriting it with your program you'd only need to check the first word is correct.

pword var word
index var word

index = $7F40
LCDOUT ... clear screen and home command
READCODE index,pword
IF pword = $700E THEN
LCDOUT “  Loader exists   "
ELSE
LCDOUT “Loader Overwrite"
ENDIF