Atmel 328 ext. interupts

comp.arch.embedded
Atmel 328 external interupts

	I'm debugging an Atmel AVR 328 that won't generate an external #0 
interupt. At present, the timer1 is generating an overflow interupt as would 
be expected. The input for the #0 ext. interupt (pin 4, d port #2) has been 
set to generate a mimic signal on another pin, which worked well.
	The setup for interupt 0 is:
  ldi areg, 2			; external interupt #0 occurrs on fallling edge
  sts EICRA, areg
  ldi areg, 1			; enable interupt #0
  sts EIMSK, areg
	The possibly of a "power management" bit needing attention exists or maybe 
a variation between the 328 and the 168 device that I've missed. 

Anyone have a suggestion?

Hul