Puzzling issue with I2CWRITE to 24LC512

[sayzer]

You should post the code in which you read EEPROM back and display on LCD.

Also, write cycle time for 24LC512 is stated to be 5ms max. in datasheet but I would make it 10ms.

Also, if your circuit powered by less then 5V then you should slow down the lines to EEPROM.

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[aberco]

Thanks for your reply!

"Also, write cycle time for 24LC512 is stated to be 5ms max. in datasheet but I would make it 10ms."

Yep I know, I actually used 10ms at first, even changing it to 500ms for test purposes. Doesn't make any difference: when I use the subroutine alone it always work, but not in my main program.

My circuit is powered by regulated 5V also...

I have attached the complete code where the I2CWRITE routines are not working. I'm still working on it so it may not be the cleanest and needs a bit of tweaking, but everything else work.

The part of the code where I read the eeprom is the subroutine "read_mode". This is also where I added lines to output the variables to LCD for debugging (they are now removed, but it worked as I could read correct values that I programmed manually with an I2C memory programmer).

Still investigating on my side...

[aberco]

Haha!!! got it!!

Erratic operation lead me to think it was a software problem, but good think you takled about VCC!!

I actually put my ajustable regulated powersupply and checked again... VCC was 7.5V!!! but everything else was working fine!

I will have to check what's going on with my 7805, but in any case, when VCC = 5V, the EEPROM works, and i can retrieve the correct values :-)

Well, as always it is super simple when you find it out! (took me 3 days though!!!).

[aberco]

Project is done and working perfectly!

It certainly have helped getting your opinion.
Many thanks!