david_farrell wrote on Saturday, August 23, 2008:
Sorry about Hijacking the thread, the low power theme is of great interest to me.
What you are describing is more significant than just your low power problem. I think
you are saying that the complete context is not saved and your solution is
overriding this error. You should examine the stack to see what SR is pushed. I suspect
the SR is pushed twice, once by the halt which is the correct one, and once
by the port code which is the SR of the low power state. Maybe a fault is occurring
and the SR of the NMI is somehow being used.
Some of what you are doing is supposed to happen automatically. Maybe errata?
slau056g.pdf p.32 "6) The SR is cleared with the exception of SCG0, which is left unchanged.
This terminates any low-power mode. Because the GIE bit is cleared,
further interrupts are disabled."
For my application (SAM9XE) I can see where the context save and restore may have to
include several hw register to preserve the power state of the instrument I
am designing.
You may want to try contacting Milos Prokic