On 24 abr, 04:01, Rich Webb wrote:
Hmmm. May have to sleep on this one.

Does the processor's oscillator stay running while the device is in
standby? The 89S52 does have a sleep mode where it turns the oscillator
off but if it is responsible for waking up the rest of the device then
I'd guess that it must stay running.

If the oscillator stays running, given that the problem behavior also
occurs when it goes to wake up the rest of the system from a state where
it itself has already initialized, then it does sound like a firmware
problem. Might be something like: wait for N timer ticks and if X has
not happened then perform error recovery; but the actual time between N
ticks can range from (N-1) to (N+1) if the waiting started just before
or just after a tick event.

--
Rich Webb * * Norfolk, VA

The oscillator is running all the time. Don't know if it goes to some
idle mode but signals from the IR sensor and buttons change INT0 input
(pin 8 of TQFP package).

I tried to downgrade to an older firmware and the behavior is the
same. I think flashing another firmware only changes the firm for the
video decoder and not the code in the Atmel.

I thought maybe stopping the oscillator for a second or two while in
the wait loop will fix the problem. I tried to manually ground the
crystal output (I can see the dashes stop moving) and when it works it
doesn't reboot, but sometimes will go crazy probably due to poor or
intermittent contact I do with a wire to the crystal solder joint.