Lpc2000

---- Original Message ----
From: "stefano_m_a" <stefano_mora@...>
To: <lpc2000@yahoogroups.com>
Sent: Thursday, May 25, 2006 2:47 PM
Subject: [lpc2000] Re: Olimex LPC2294H external flash

> is it possible to save some routines into the external flash (but
> boot into the internal one..) ?
> I try to modify my linker script adding an output section to point
> 0x8000.0000 area.
> I receive the following errors:
>
> Linking: main.elf
> arm-elf-gcc -mthumb -mcpu=arm7tdmi -mthumb-interwork -I. -gdwarf-2 -
> DROM_RUN  -O0 -Wall -Wcast-align -Wcast-qual -Wimplicit  -Wpointer-
> arith -Wswitch -Wredundant-decls -Wreturn-type -Wshadow -Wunused -Wa,-
> adhlns=crt0.lst   -MD -MP -MF .dep/main.elf.d crt0.o   lcd.o system.o
> buttons.o LPC_uart.o LPC_Vic.o adc.o armVIC.o ram.o main.o     --
> output main.elf -nostartfiles -Wl,-Map=main.map,--cref -lc  -lm -lc -
> lgcc -TLPC2214-ROM.ld
>
> ram.o: In function `RAM_read':
> /cygdrive/j/Progetti/Lpc/Progetti/FlashExt/ram.c:38: relocation
> truncated to fit: R_ARM_PC24 against symbol `LCDSendCommand' defined
> in .text section in lcd.o
> /cygdrive/j/Progetti/Lpc/Progetti/FlashExt/ram.c:47: relocation
> truncated to fit: R_ARM_PC24 against symbol `LCDSendChar' defined
> in .text section in lcd.o
> ram.o: In function `RAM_read_rev':
> /cygdrive/j/Progetti/Lpc/Progetti/FlashExt/ram.c:55: relocation
> truncated to fit: R_ARM_PC24 against symbol `LCDSendCommand' defined
> in .text section in lcd.o
> collect2: ld returned 1 exit status
> make: *** [main.elf] Error 1

Internal and external flash are further apart than can be spanned by a bl 
instruction, so you cannot call from internal to external flash or 
vice-versa with normal bl instructions.  Try:

/* file1.c */
int ext_flash_function (int i)  __attribute__((long_call));

int int_flash_function (void)
{
  ext_flash_function(1);
}

/* file2.c */
int ext_flash_function (int i)
{
  return i+i;
}


The long_call attribute tells gcc to use an indirect call when calling 
ext_flash_function().  This is larger and slower, but the callee can be 
anywhere in the address space.

Karl Olsen