[Tinyos Core WG] Re: [Tinyos-devel] micaz (atm128?) serial problem in 2.x

[Philip Levis]

On Oct 2, 2006, at 9:12 PM, eweddington at cso.atmel.com wrote:

> Hi Phil,
>
> I would rule out a stray memory bug causing the watchdog to be  
> enabled.
> On the mega128, it requires a specific code sequence to enable the
> watchdog, which a stray memory bug probably won't be able to do.

Agreed. But looking at the reset conditions, I'm hard pressed to come  
up with an alternative explanation. There are five causes:

Power-On Reset
External Reset
Watchdog Reset
Brown-out Reset
JTAG AVR Reset

I first encountered the problem on motes that were plugged into EPRB  
boards so had power over ethernet. It only happens when they are put  
under significant load. I've had it happen on nodes that were battery  
powered as well.

> IIRC, there is a register in the m128 that allows you to discover the
> source of a reset. Sorry, I don't have the datasheet in front of  
> me, so
> I don't know the specific register. But I would suggest putting in  
> some
> debug code to take a look at that and see if that provides any further
> clues.

Good point: the MCUCSR. I'll take a look.

This is a weird one, and I'm hard pressed to come up with a  
reasonable explanation for it. But hopefully the MCUCSR will tell the  
story...

Phil