EEPROM changes at 16F84

[biga]

I am having serious problem with EEPROM in PIC16F84. It seems that some EEPROM adresses changes when circuit is plugged on. I used some kind of filtration on Vdd and Vss pins with 2 inductor and one capacitor. That thing worked with PIC12C519 and its EEPROM, but now it seems that it doesn't work. Can anyone help me with this?
Igor Bigic
R&D engineer
Belgrade
Serbia and Montenegro

 

[kinjalgp]

What do you mean by address changes? I am sure you don't mean there are physical address changes. I guess you mean to say the EEPROM data is getting corrupted everytime you power up. On of the reason of this may be supply voltage surges. Use adequate filtering in your power supply. Use 10uF and 100pF capacitors in parallel at the output of 7805 regulator.
Also use decoupling capacitor of 0.1uF just near the supply pin of 16F84.

If you are working in too noisy envionment then a 2.5 turn ferrite bead inductor is also recommended in the supply rail.

 

[biga]

Yes,
I meant that data on some adresses has been changed when I turn the power on. I will try with these capacitors, but I have 0.1 uF near the Vdd pin, and I also have two inductors of 47uH.
Thanks.