PIC18F4550 EEPROM Memory Failure
I have 35 of the same devices with a 18F4550 PIC as its main controller. When new, the devices work fine, they collect data and store it in the EEPROM. However, I have had a few older units where a specific memory location 0x12 will not function correctly.
When attached to the PICKit3, I can see the code addresses (watching EEADR=0x012) the correct memory location and writes the correct data (EEDATA=0x01) but when reading the data back it reads empty (0x00). It only appears to be this memory location as other locations read correctly. Is it heard of that one location can fail? .