PIC 18F4550 modifying internal eeprom

[otavio_fisica]

Hi everyone,

Here I am for sharing a problem I have with PIC18F4550.
The problem is that when I try to run a large program (typically 97% of the rom memory) the pic starts changing the values from some eeprom memory positions. If I run a smaller version of the same program (typically 80% of the rom memory) the problem doesn't appear anymore.

The test is the following:
1. I program the pic with all the eeprom memory filled with the same random value.
2. The pic program shows in a display the value from two positions of the eeprom memory.
3. Then I put the pic in my circuitry and turn it on and off some times.
4. After some time it changes the values from the memory. I can see it in the display and when I take the pic out of the circuitry and read the eeprom memory, I see that other memory positions changed.
5. I repeat the procedure with the smaller code... the problem is not observed anymore.

What's stranger is that in my code there's no routines for changing these memory values. I don't have any idea why these values change when I do the tests.

I use the CCS compiler version 4.013.

Is that a compiler problem? Has anybody ever had this sort of problem?
Any help will be very useful.

Thanks.
Otavio Gomes.

[PCM programmer]

[otavio_fisica]

Thanks for your ready answer.

I have just made the same tests with the compiler 4.088 from a friend. The problem still persists. Does anybody have any ideas about this?

[PCM programmer]

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