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[on:]

I'm just getting started using Arduino.

I upload my program to the board and it runs. But if the board loses power the program is gone next time I supply power. How can I keep the program on the Uno and be able to turn it off and on? Or do I need to keep power to the board so that it is always 'on'? If so how much current would the Uno typically draw if the program were in standby mode and not really doing anything?

[Reply #1 on:]

But if the board loses power the program is gone next time I supply power

Are you sure? That is not how the arduino works.

It retains the program until you replace it, whether it is powered or not.

[Reply #2 on:]

Are you sure? That is not how the arduino works.

It retains the program until you replace it, whether it is powered or not.

Hmmm...

You're right. It does still work after a power loss. That's going to make things a whole lot easier.

Thanks for the prompt help.

[Reply #3 on:]

Just to expand a bit in case you were not aware, the program is stored in flash memory, like in a USB flash drive, SD flash memory card, etc. -- no power required once it's stored. The datasheet says the data will be retained for 20 years at 85°C or for 100 years at 25°C.