I have a bootloader residing at locations 0x0000 to 0x0fff on an 8-bit PIC18F. How do I tell the XC8 compiler to output a hex file which starts at 0x1000?
With a CCS compiler my friend is using, he's using the following code:
#define LOADER_SIZE (0xFFF)
#define LOADER_START (0)
#define LOADER_END (LOADER_SIZE)
#define APPLICATION_START (LOADER_SIZE+1)
#define APPLICATION_END (getenv("PROGRAM_MEMORY")-1)
#define APPLICATION_ISR (APPLICATION_START+8)
#ifdef _BOOTLOADER
//in the application, this moves the reset and isr vector out of the bootload
//space. it then reserves the loader space from being used by the application.
#build(reset=APPLICATION_START, interrupt=APPLICATION_ISR)
#org 0, LOADER_END {}
#endif
Digging around the Microchip Libraries for Applications (MLA), I found this for the C18 compiler, however the XC8 compiler does not recognise "#pragma code".
#define REMAPPED_RESET_VECTOR_ADDRESS 0x1000
#define REMAPPED_HIGH_INTERRUPT_VECTOR_ADDRESS 0x1008
#define REMAPPED_LOW_INTERRUPT_VECTOR_ADDRESS 0x1018
extern void _startup (void); // See c018i.c in your C18 compiler dir
#pragma code REMAPPED_RESET_VECTOR = REMAPPED_RESET_VECTOR_ADDRESS
void _reset (void) {
_asm goto _startup _endasm
}
#pragma code REMAPPED_HIGH_INTERRUPT_VECTOR = REMAPPED_HIGH_INTERRUPT_VECTOR_ADDRESS
void Remapped_High_ISR (void) {
_asm goto YourHighPriorityISRCode _endasm
}
#pragma code REMAPPED_LOW_INTERRUPT_VECTOR = REMAPPED_LOW_INTERRUPT_VECTOR_ADDRESS
void Remapped_Low_ISR (void) {
_asm goto YourLowPriorityISRCode _endasm
}
#pragma code HIGH_INTERRUPT_VECTOR = 0x08
void High_ISR (void) {
_asm goto REMAPPED_HIGH_INTERRUPT_VECTOR_ADDRESS _endasm
}
#pragma code LOW_INTERRUPT_VECTOR = 0x18
void Low_ISR (void) {
_asm goto REMAPPED_LOW_INTERRUPT_VECTOR_ADDRESS _endasm
}
Best Answer
A quick search led me to this Microchip forum discussion where the solution appears to be specifying --CODEOFFSET as one of the linker arguments.
The forum also has a link to a webinar on the same topic.
Command line:
You can pass the offset when compiling with the command line by passing
--codeoffset=<location>
during linking (i.e.--codeoffset=0x1000
).MPLABX IDE
Specify the code offset by accessing project properties -> XC8 global options -> XC8 linker, changing the Option categories: to Additional options, and entering the offset in the Codeoffset field: