Best approach to make arduino sleep, then wake up and take a measurement

Projects General Guidance
1

Hi all, I'm working on a project that i only want to work in the dark - I would like the arduino to sleep for a set period of time (5 minutes maybe), then wake up and take a reading from a LDR - then decide if it needs to stay awake or not.

I'm struggling with the sleep part at the moment. I read somewhere that the arduino can only sleep for 8 seconds using the internal timer to wake itself up, is that correct? I would rather not use an external trigger if I don't have to so I can keep the hardware to a minimum

Thanks!

2

Take a look at Nick's page on power.

Also take a look at this example called Nightingale

3

thanks :slight_smile: having a quick look, it does not seem possible to make the arduino sleep for any longer than 8s on the internal clock - is that a correct assumption? thanks

4

Quote from the link
"Note that the smallest is 16 mS and the longest is 8 S.

You could arrange longer sleep times by having a "counting" loop and sleep/wake/sleep/wake for x times."

So you have to nurse it like a baby and put it to bed many times. But putting it back to sleep wouldn't take long / a lot of power.

5

dtokez:
thanks :slight_smile: having a quick look, it does not seem possible to make the arduino sleep for any longer than 8s on the internal clock - is that a correct assumption? thanks

maybe Nick needs to up-date his page.
http://forum.arduino.cc/index.php?topic=330138.0

6

dave-in-nj:
maybe Nick needs to up-date his page.

Why? All I can find in that topic is putting it to bed many times....