Subject :  RE: 80CL580 sleep mode
  From    :  Scott May <scott@smartdata.com.au>


> Does anyone out there have any experience using
> sleep mode?  I am using external 2 to wake up
> the micro.  However, the spec sheet (80CL580)
> says that the oscillator is unavailable for
> roughly 1600 oscillator periods after the
> interrupt is received.  I'm using
> an 8 MHz oscillator, so this corresponds to
> about 200 microseconds.  What I am seeing is
> that the the time between the interrupt and
> the oscillator being available is actually
> about 800 microseconds.

There'll be 200uS delay from when the oscillator actually oscillates.  The startup time for any crystal oscillator can vary between less that what you have, to up to up a second in very low power designs.  To improve on what you have, try looking for crystals with different characteristics, in particular, drive level required.  Also, the caps you have hanging off the crystal, if any, may be varied, to see what you get.