2012-04-11, 09:29:22
Apologies, I exported the program memory from MPLAB without first reading back all the bootloaded code into MPLAB. Here's another try.
I've been trying to work out how and when the bootloader writes the start address. The protected goto code appears to overwrite the bootloader start address whenever the GUI/hex file tries to write to block zero, which makes sense in case of an incomplete download, but does the GUI add a line at the end to rewrite the goto address to the user code's address? If so, this seems to be what's missing. Whatever I do, with or without the goto protection, the first 4 bytes read "goto <bootloader address>" from very early in the bootloading process (if I interrupt it) to the very end. I even manually added a line at the very end of the hex file to write the correct address but either this didn't get written or was subsequently overwritten by the GUI.
I've been trying to work out how and when the bootloader writes the start address. The protected goto code appears to overwrite the bootloader start address whenever the GUI/hex file tries to write to block zero, which makes sense in case of an incomplete download, but does the GUI add a line at the end to rewrite the goto address to the user code's address? If so, this seems to be what's missing. Whatever I do, with or without the goto protection, the first 4 bytes read "goto <bootloader address>" from very early in the bootloading process (if I interrupt it) to the very end. I even manually added a line at the very end of the hex file to write the correct address but either this didn't get written or was subsequently overwritten by the GUI.