Gerard Sequeira wrote:
> I copied armVIC.c armVIC.h and crt0.S into my working directory.

I suggest to copy the linker-script too.

> On compiling with THUMB mode, I get these errors:
> /tmp/ccqbN0BB.s: Assembler messages:
> /tmp/ccqbN0BB.s:715: Error: lo register required -- `sub lr,lr,#4'
> ...

Yes, the macros expand to some inline assembler instructions which are
for ARM mode only so the code has to be compiled in ARM-mode.

> On compiling in ARM mode with -mthumb-interwork, I get these errors:
> crt0.o: In function `_reset':
> crt0.S:166: undefined reference to `_stack'
> collect2: ld returned 1 exit status
> make: *** [srv1.hex] Error 1
>
> Is there a file I'm missing out?

Maybe your "old" linker-script just does not provide the needed
information (address of _stack). Try to compare your linker-script with
the linker-script from my example or just try to use the script from the
example.


Martin Thomas

Thank you so much for your reply.

That got rid of the errors.
Since I'm  loading into RAM,I get a warning:cannot find entry symbol
_start

arm-elf-gcc main.o uart0.o uart1.o iap.o armVIC.o utils.o
startup/libea_startup_thumb.a  -I./startup -mcpu=arm7tdmi
-mthumb-interwork -nostartfiles -T build_files/LPC2106_RAM.ld -o
srv1.elf -Wl,-Map=srv1.map,--cref
/opt/arm-elf-tools/gcc-4.1.1/lib/gcc/arm-elf/4.1.1/../../../../arm-elf/b 
in/ld:
warning: cannot find entry symbol _start; defaulting to 40000000


Though I can copy my hex file, my program wont start, maybe because of
no _start?

Gerard Sequeira wrote:
> Thank you so much for your reply.
>
> That got rid of the errors.
> Since I'm  loading into RAM,I get a warning:cannot find entry symbol
> _start
>
> arm-elf-gcc main.o uart0.o uart1.o iap.o armVIC.o utils.o
> startup/libea_startup_thumb.a  -I./startup -mcpu=arm7tdmi
> -mthumb-interwork -nostartfiles -T build_files/LPC2106_RAM.ld -o
> srv1.elf -Wl,-Map=srv1.map,--cref
> /opt/arm-elf-tools/gcc-4.1.1/lib/gcc/arm-elf/4.1.1/../../../../arm-elf/b in/ld:
> warning: cannot find entry symbol _start; defaulting to 40000000
>
>
> Though I can copy my hex file, my program wont start, maybe because of
> no _start?

To get rid of the warning add a label in the startup-code just above the
reset-vector "ldr pc".
Since you are "loading into RAM": Are the interrupt-vectors in place?
Remapping set correclty? Does the programming software set the PC to the
start-address (usualy the reset-vector execption address)? When using
ISP: check the user-manual the bootloader uses some bytes in RAM, so
maybe user-data gets overwritten. Difficult to help without knowing the
code (what is "libea_startup_thumb.a"?). You may create a minimal
example to reproduce the problem (full code, linker-script, makefile)
pack it and place it on a server than post the URL here.

I managed to compile everything.
As in your example the ISR entry and exit assembly stubs are inserted.
However the processor still resets at times.
Compiled with ARM (no interwork)

Is this the same way the following problem was solved?
http://en.mikrocontroller.net/topic/102252#224743

My routine:
/*Capture1.3/1.2 interrupt*/
void _attribute_ ((interrupt(naked))) captureISR(void){


        asm("sub lr, lr,#4");
        asm("stmfd sp!, {r0-r12, lr}");
        asm("mrs r1, spsr");
        asm("stmfd sp!, {r1}");

        count_int++;
        count_int_poll++;
        //unsigned int x=(PI*DIAMETER*count_int_poll)/TICK;
        //printNumber(10, 8, FALSE, ' ', x);

        T1IR |=         0x80;//|0x40;        //clear T1 CAP1.2 and
CAP1.3 interrupt
        VICVectAddr =   0x00000000;       //Dummy write to signal end of
interrupt
        asm("ldmfd sp!,{r1}");
        asm("msr spsr_c,r1");
        asm("ldmfd sp!,{r0-r12,pc}^");
}

Please define "still resets at times". Maybe you see "spurious"
interrupts which would be not that unusual when using external capture
and a high frequency input signal. Is there an ISR which manages
"unvectored" interrupts (ISR at the VIS's default vector address)? Is
this ISR called? For a test increase a volatile counter in the default
ISR, clear the interrupt in the ISR and check the counter in main-loop.

Just a side-note: I suggest to keep the assembler instructions for a
sequence in a single asm volatile. There are tested macros for this see
i.e. the macros in armVIC.h (created by Bill Knight and included in some
of the examples in WinARM or from my Web-pages).