Hi to all,

first of all i want to greet all people in this famous forum, where i'm reading some weeks ... but this is my first posting. Maybe someone has some suggestions on this strage effect

We were using an AT91SAM7X256-AU, which is working pretty good. But as we have absolutely no RAM and nearly no FLASH free for our further development, we decided to change to the AT91SAM7X512-AU. This is also working quite good (we managed to buy some first devices for a much too high price, but they are hard to buy at normal distributors at the moment), but one effect costs me more than the half of today.

As soon as i just enable the Watchdog timer (really just enable(!), without any reset or interrupt action on error or timeout), the processor freezes after some tens of milliseconds after startup. I see the first few lines of status output on the debug port, and then it just freezes. This happens only when no debug intetface is connected, as soon as the CPU runs under JTAG, this does not happen (even if WD is enabled also during debug). So, no chance to catch this with a connected debug interface.

The WD timer is set to 5 seconds, so there is no timeout action causing whatever happens after few tens of ms.

Enabling now the WD action to make it a reset after timeout, the same happens: It freezes after some ten of milliseconds, the WD reset fires a reset after 5 seconds, the device restarts, freezes again after the same time, WD reset after 5 seconds and so on.

At this point i really have no idea what is happening here, as it is the same core, the same registers, the WD generally working (it makes the resets after the 5sec timeout) ... but the CPU freezing after a short time after restart.

Any ideas are highly appreciated