Why is the stop3 condition on the S08QG8 so elusive?

[sauz22]

We are still having trouble with our CW & PE development of the battery supported application because we do not know, clean and clear, how to get the low power regime the application is intended to work with. We need to wake up the device with a KBI interrupt but the sad truth is that sometimes that wake up does not occurr at all, and sometimes it seems the clocks are disturbed after the wake up. What are the real factors to work with stop3? What modules may work after leaving the condition? What is the effect the pull ups produce? We need to program it using assembly instead? Are 65 microAmps a good consumption in stop3? May we use an interrupt from a timer after the wake up?

[tonyp]

65uA in STOP3 is certainly over the specification's maximum of 6, unless you're measuring your whole circuit's current draw, not just the MCU's.

Regardless, whether this is good or not depends on your design's average consumption, the battery's mAh rating, and the minimum acceptable battery charge/replacement intervals for your design.  We've found (with a different chip) that if we follow the (manufacturer's) recommendation to tie all unused pins (assuming there are any) to either ground or Vdd (as inputs, of course) that we get very close to the specifications.  Also, shut down all but the necessary internal/external peripherals before entering STOP (e.g., A/D module, if not expected to exit STOP via A/D interrupt).

Hope this helps.