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picamera minimize power consumption

Posted: Fri Jun 14, 2019 11:21 am
by miky94
hope this is the right forum
I'm developing a timelapse camera using camera module v1, I take a picture every 10 seconds and I was wondering if to use stop_preview() after each shot and then start_preview() 2 seconds before the next could make my battery last longer.
also how can I detect when there's low light? for example reading the value of each pixel to see how many are over a black threshold?

Re: picamera minimize power consumption

Posted: Fri Jun 14, 2019 3:09 pm
by HermannSW
I doubt that you can increase battery lifetime much with that, since no Pi model has any sleep modes like ESPs or Arduinos.

In "1W server challenge" thread I first measured an ESP32-CAM module to use 186mA at 3.3V only:
viewtopic.php?t=238870#p1461306

I was totally surprised that Pi0W with a simple USB webcam only uses 0.253A at 3.3V, which is 0.835W and below 1W:
viewtopic.php?f=36&t=238870&start=50#p1463371

I did not measured Raspberry camera power consumption sofar.

Re: picamera minimize power consumption

Posted: Sun Jun 16, 2019 11:16 pm
by miky94
of course we are talking about a few milliamps, but I think while the preview is stopped the Pi is not elaborating, right?

in fact I read here https://projects.raspberrypi.org/en/pro ... picamera/6 that it is important to sleep for at least 2 seconds before capturing, to give the sensor time to set its light levels.

probably using a 10s lapse it doesn't make much difference but at 30s interval would be more significant

I read here https://www.raspberrypi.org/documentati ... /#pi-power the Camera Module requires 250mA

do you know how to detect darkness?