bit corruption in Atmel AT89C51ED2 internal flash

hi
working with AT89C51ED2 device from Atmel, has anyone encountered a situation in which a single or multiple bit of the internal flash image file get corrupted?
i need a few hints on this phenomena which prevent correct code execution, major suspicion is brown-out scenario?
Best regards

 RE: bit corruption in Atmel AT89C51ED2 internal flash

The first question to ask is always: Do you have a supervisor for the supply voltage, that makes sure the processor is always in reset state if the voltage isn't stable?

Next thing is that the chip requires temperature and voltage to be within range - and the voltage stable - to be able to correctly program the flash.

 clarifying the important point

Do you have a reset supervisor, if not you will occasionally lose the flash. RC reset is NOT sufficient for flash based devices.

Erik

 RE: clarifying the important point

hi
thanks for all the answers, just to clarify more, i currently have a external POR device, one thing i think of is that it can get into contention with the internal POR/WDT/PFD circuits that drive reset out if asserted.
Guy.

 RE: clarifying the important point

I'm having similar problems with an 89C51RC2. I occassionally get the first 128 bytes of flash set to FF. I have no power supply supervisor. Is it likely that an entire half page of memory gets corrupted by a brownout. I don't seem to be able to replicate this on the bench but I have had equipment returned with 'dead' processors which have this fault.

Has the original poster resolved his issue?

 RE: clarifying the important point

i currently have a external POR device, one thing i think of is that it can get into contention with the internal POR/WDT/PFD circuits that drive reset out if asserted.
when using "a external POR device"ith a chip that has "internal POR/WDT/PFD circuits that drive reset out" it is essential not to use a push-pul output supervisor.

I'm having similar problems with an 89C51RC2. I occassionally get the first 128 bytes of flash set to FF. I have no power supply supervisor.
then add one (see note above)

Erik

 RE: clarifying the important point

hi
i haven't resolved this issue yet, another solution to the internal POR contention with the external POR is inserting a series resistor/DIODE between the external Reset pin of the POR device and the reset pin of the 8051.
as suggested in the 8051 HW design guide.
BR
guy