Help with Amtel at89c52 hardware question.

Thread Starter


Joined Feb 4, 2009
Hi All,

I have a back to the future time circuit box that displays as in the Back To The Future movie.

All three lines can be programmed but when power is removed the unit defaults back to its original power on settings and i have to punch the details in again.

Is there any way to maintain the memory of the at89c52 so when power is applied to the unit the last settings are still there?


Fred/New Zealand


Joined Aug 15, 2007

You will need some type of non-volatile memory (N-V M) such as an EEPROM. You should also have a brown-out detector so you do not write to the EEPROM as your disconnected power supply is dying. The software should write the time to the N-V M every time it updates the smallest time unit displayed, withing the constraints of the N-V M.