Hi,
I'm using sdcc with an pic18f2550 (with varying success), maybe I can provide
some help (Not for win95 or USART, I don't use them).
On Tuesday 09 January 2007 14:26, Gyorgy Horvath wrote:
> 3. /sdcc/lib/src/pic16/startup
> Since startup code does not reflect to linker script
>
> CODEPAGE NAME=vectors START=0x800 END=0x829
> PROTECTED
> CODEPAGE NAME=page START=0x82A END=0x7FFF
>
> or --ivt-loc=0x800 either we had to do something...
>
> When I am using BRAND USB boot-loader, I have to
> prep the following as a workaround:
>
> /**/
> /* - Special remapping of vectors to 800 - tweaking crt0 */
> /* for AN956 USB boot loader */
> /**/
> #pragma code _reset 0x000800
> void _reset( void ) __naked
> {
> __asm
> EXTERN __startup
> goto __startup
> __endasm;
> }
> #pragma code _high_ISR 0x000808
> void _high_ISR( void ) __naked
> {
> __asm
> retfie
> __endasm;
> }
> #pragma code _low_ISR 0x000818
> void _low_ISR( void ) __naked
> {
> __asm
> retfie
> __endasm;
> }
>
> It seems quite ugly.. Do you have better solution?
Well, one solution would be using a custom initialization, here's how I did
it:
Compiling with --ivt-loc=0x800
Linking with -Wl,-s,bootloader.lkr --use-crt=bootloader_crt0i.rel
bootloader.lkr:
CODEPAGE NAME=boot START=0x0 END=0x7FF PROTECTED
CODEPAGE NAME=vectors START=0x800 END=0x829 PROTECTED
CODEPAGE NAME=page START=0x82A END=0x7FFF
...
bootloader_crt0i.c is just a copy of the original crt0i.c file, it only needs
to be compiled with the --ivt-loc switch.
ISRs etc are defined in main.c just as they would be without a bootloader:
DEF_INTHIGH(high_isr)
DEF_HANDLER(SIG_TMR3, timer3_handler)
END_DEF
SIGHANDLER(timer3_handler) {
...
}
DEF_INTLOW(low_isr)
DEF_HANDLER(SIG_TMR0, timer0_handler)
END_DEF
SIGHANDLER(timer0_handler) {
...
}
and so on.
While the interrupts basically work, their entry code still seems to have some
issues. From time to time the ISRs seem to scramble the results of the
Calculations they interrupt.
I'm not sure yet if its a problem with all the array accesses I'm using (they
seem to fail fairly often), or with the high ISR interrupting the low ISR,
scrambling the data the low isr saved.
(last tried with Version #4497 (Dec 2 2006))
Greetings,
/Ernst
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