Has anybody noticed that EEPROM can be faulty?
First I suspected bad coding. Then I suspected RAM overfill, so I deleted all RAM hungry parts, so that RAM usage was left at only 550bytes.
Still nothing. EEPROM gets Written at locations that code never uses, and gets read back false values. Randomly and seldom. I could not determine any pattern how errors occur. Reading of false values made me think that it could be a EEPROM fault. As during the next read from the same EEPROM location value is correct. Actually most of the times. And code is the same. It is not changed between the reads.