Lpc2000

I have some doubts regarding Interrupts.
what is the difference between Vectored and non-vectored interrupts?
what is advantage of vectore interrupt over non vectored interrupt?
please clarify if any body knows

At 11:01 AM 4/8/04 +0000, you wrote:
>I have some doubts regarding Interrupts.
>what is the difference between Vectored and non-vectored interrupts?
>what is advantage of vectore interrupt over non vectored interrupt?
>please clarify if any body knows

Vectored interrupts use some sort of priority scheme and an address table 
to respond to ("vector" ) the incoming interrupt to its corresponding 
interrupt service routine.  Non-vectored interrupts feed multiple 
interrupts into a single interrupt service routine that must then determine 
which interrupts fired and service them appropriately.

The vector interrupt unit in the LPC provides a way to give vectored 
interrupt using what is essentially a non-vectored interrupt setup.  By 
using one instruction at the beginning of the ISR the processor can jump to 
an appropriate routine to service the highest priority pending 
interrupt.  Since not all interrupt sources can be dealt with via the 
vector unit the lowest priority slot is reserved as a catchall for any not 
already serviced (reverting back to a non-vectored type of response).

The advantage of vectored interrupts?  The prioritization takes place in HW 
and is thus faster and less prone to race conditions.  Also for the 
vectored interrupts there is no time and effort spent determining the 
source of the interrupt.

Robert


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