Lpc2000

--- In lpc2000@yahoogroups.com, "mgiaco82" <mgiaco82@...> wrote:
>
> I found this on the Page from Rowley.
> 
> >>I'm trying to use vectored interrupts on the LPC2000. I've 
> programmed >>up the VIC but when the interrupt occurs the program 
> jumps to >>the "irq_handler" label/function, not the ISR I have 
> configured using >>the VIC.
> 
> >>How do I make the LPC2000 jump to my vectored ISR when the 
> interrupt >>occurs? 
> 
> Answer:     
>  
> You need to have the instruction "ldr pc, [pc, #-0xFF0]" located at 
> the IRQ exception vector for vectored interrupts to work.
> 
> To do this make sure you have the preprocessor definition 
> VECTORED_IRQ_INTERRUPTS defined when you compile the 
> Philips_LPC210X_Startup.s file.
> 
> This mean i have to define anything before i can use the vic?
> Can anybody explain pleas.
> 
> thanks mathias
>

Yes, you have to do 'something' to alter the way in which the startup
file is assembled.  Look at the Philips_LPC????_Startup.s file. 
Somewhere (maybe around line 86) you will find:

#ifdef VECTORED_IRQ_INTERRUPTS
  .word 0xB9205F84                    /* boot loader checksum */
  ldr pc, [pc, #-0xFF0]               /* irq handler */
#else
  .word 0xB8A06F60                    /* boot loader checksum */
  ldr pc, [pc, #irq_handler_address - . - 8]    /* irq handler */
#endif

One way to get VECTORED_IRQ_INTERRUPTS defined is to put, at the top
of the .S file:

#define VECTORED_IRQ_INTERRUPTS

Maybe put that just before:
  .section .vectors, "ax"

If you do it that way, you will want to import the .s file to the
specific project rather than linking to a modified master copy.  Right
click on the file name in the Project Explorer dialog and select
Import.  Put the copy with the other source files for the project.

There is probably a much better way to do this.  At the moment, I
can't find it.

Richard