[Tinyos Core WG] button and TEP 112

[Philip Levis]

How does this sound:

Following Gil's observations, the simple interface to a button uses  
SIDs. Notify for state change (with a bool for the state) and Get for  
state querying. So there's something like

component TelosUserButtonC {
   provides interface Notify<bool>;
   provides interface Get<bool>;
}

One difference here is that there is no enable/disable. This would  
assume either the abstraction is dedicated or using generic  
components (with a masking scheme for inactive clients). I'm not sure  
which would be a better approach. In theory, you can always build the  
latter on top of the former.

The ButtonAdvanced is a little tricker. Its exact semantics aren't  
that clear from the source code, but that could be fixed later.   
Again, I think Gil is right that it's for a particular sensor  
processing scheme, in that it allows certain operations and not  
others. It would also be tricker to make into a service (or at least  
more expensive), due to the need for per-instance timers. But that is  
unlikely to be an issue. I could certainly imagine other higher-level  
interfaces, such as one that reports single clock events with the  
duration the button was depressed.

Concrete proposal:

discard Button, use SIDs
bring up ButtonAdvanced at next meeting to discuss whether it should
   1) Exist as is without any changes
   2) Exist as is but be renamed
   3) Be changed but keep the same name
   4) Be changed and be renamed

I personally lean towards 2 or 4; we should either keep it as and  
name it ButtonMulti or perhaps make it a bit more general and name it  
Button.

I hope to get the recommended edits into TEP 112 (and take a look at  
the atm128 timer system wrt McuPowerOverride) early this week so we  
can move forward on it. Apologies for the delay: the past few weeks  
have been spent trying to finish up the last rough edges on the  
release and traveling like mad.

Phil