Could somebody help me or give me some idea with following problem:
I am using microcontroller AT89S8252 (dip 40) (24 PI; 0544), and AT45DB041B (SO8) data flash on my board(name of the board is: Konzola; just for understanding). Board is control unit in automotive environment (it is board which controls LCD display and communicates by RS485 (without optoisolation) with display unit in wehicle, those display units also have AT89S8252 (but PLCC44), display units didn't have problem of that kind. Board has DC-DC buck converter 24V to 5V.
The problem is:
Flash of microcontroller and data flash were erased after some period of time, there are no other visible problems on the board.
When I reprogram flash of the mcu and dataflash everything works fine for a few days or weeks, but both flashes are again erased. I have changed circuits on board (AT89S8252 (dip 40), and AT45DB041B (SO8)) but problem wasn't solved.
I would be grateful if you could help me to solve that problem. If you have some questions please be free to contact me.


Thank you in advance.