Evolution of a Blog

This blog has evolved as I have as a maker. It starts at the beginning of my journey where I began to re-tread my tires in the useful lore of micro electronics and the open-source software that can drive them. While building solutions around micro-electronics are still an occasional topic my more recent focus has been on the 3D Printing side of making.

Thursday, April 4, 2013

RPi as a CritterCam - Ultimately Remoting a DSLR

I have made some progress on a CritterCam based on one of my RPi's.   Here are a couple pictures of the device:

  • The base is a four battery holder for 3.7v 1850 Lithium Ion flashlight batteries with an output of 14.8v.
  • At the top is an adjustable power regulator that drops the 14.8v to 5v and delivers it via a 5.2mm power plug.
  • The power regulator is sitting on a powered USB hub that provides power to the RPi and also supports a Wi-Fi dongle (and a keyboard during debugging).  The hub is a cheap one but compatible with the RPi and is smaller than the more expensive ones I find on Amazon.
  • As mentioned above the Hub supports a USB Wi-FI dongle.   The one shown in the picture is an Edimax (larger of the two that I have).  I also have the small one but have been having some issues with dropped packets that I will discuss elsewhere.
  • In front of the USB Hub is the a 720p WebCam that is compatible with the RPi...but in my case only if plugged directly into the RPi.
  • Inside the Adafruit case is, of course, the Raspberry Pi that drives the CritterCam and it's web interface.
My goal is to use some Python code to detect motion in front of the webcam and trigger a shot by the DSLR which will be connected to the CritterCam.   The CritterCam will also support a web server running a little PHP application that will provide a preview of what the CritterCam sees.   I will talk about all of this a little later.

Right now I have a couple of issues.  First is one of power, on a couple of fronts, one being that I am using four Lithium Ion batteries to power the CritterCam and one of them has turned itself off!  I guess this is a good feature but I only have four right now but am waiting for an order from China for some more.  The other power related issue is that while I had a good test run with the Lithium Ion batteries driving the RPi for almost three hours...since then I can't get the power regulator to reliable support the RPi when connected to wall power of a variety of voltages.   The power does not seem sufficient to drive both the Hub and the RPi.   I am baffled as it worked so well with the batteries but can not retest with batteries again as I am missing one!

The other issue relates to driving the DSLR.   I have the Python code working well with the webcam on its own.   It detects motion and saves the current image.   Alas, when I try to trigger a DSLR capture at that point using the code I discuss here, it fails.   More work to do here but first I want to get the power issue sorted.

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