Hello Martin,
I also just read your previous mail on ecos-devel.
Each 12us an IRQ is indeed fast!
Using the FIQ is a good idea, but you should then not use eCos (in
vectors.S). Just write all FIQ handling code yourself in assembly then.
I have had problems with the ARM FIQ
(http://sourceware.org/ml/ecos-discuss/2007-09/msg00099.html).
Also search the mailing list for "FIQ", there are some interesting mails.
Martin Laabs wrote:
Hi,
I've been looking in vectors.S in ecos/packages/hal/arm because I
get a trap when disableing the CYGIMP_HAL_COMMON_INTERRUPTS_USE_INTERRUPT_STACK
option.
There you find the following:
IRQ:
// Note: I use this exception stack while saving the context because
// the current SP does not seem to be always valid in this CPU mode.
ldr sp,.__exception_stack // get good stack
stmfd sp!,{r0-r5} // save some supervisor regs
sub r0,lr,#4 // PC at time of interrupt
mrs r1,spsr
mov r2,#CYGNUM_HAL_VECTOR_IRQ
mov r3,sp
[...]
Does this mean, that every interrupt will use the (much to small)
exception stack if no dedicated interrupt stack is defined?
Then every interrupt will use 1 stack, and the size is determined by
CYGNUM_HAL_COMMON_INTERRUPTS_STACK_SIZE.
Kind regards,
Jürgen
Thank you,
Martin L.
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