Re: [avr-chat] mega644 resetting continuously

[Joerg Wunsch]

As "Steve Franks" <address@hidden> wrote:

>3) MCUCSR shows 0, so it must be a bug, not Hw, right?  I sure
>thought it was a runaway watchdog for a long time the way the cpu
>reset in the middle of a puts (and yes, it's a 20 char string in a
>128 byte buffer, so it's not that).  Also "WDT always on" fuse shows
>blank in avrstudio

Are you using the watchdog at all?  Please have a look at the
datasheet and the avr-libc documentation about the watchdog module:
for all recent AVRs, the watchdog remains active (with the shortest
possible timeout, i. e. about 15 ms!) across a hardware reset (except
a power-on reset, of course) once it triggered.  Also, as long as the
WDR bit in MCUCSR is set, the watchdog cannot be disabled.  Thus it's
crucial to read out and clear MCUCSR early, and disable the watchdog
immediately.
-- 

J"org Wunsch                                           Unix support engineer
address@hidden        http://www.interface-systems.de/~j/