16 volts, 10 watts AC (yep, AC, not DC) to 5 volts DC 

I have a project, to replace my doorbell

i finished my project and it works perfectly but i have one problem how can i save my code in the sd card (memory) to not lose the data if the power gose off. (bittrey gose out or power cut e.x.) The code i use is:






can enyone help me tis this problem please.