Thermal Imaging RPi Zero W

The goal here was to capture images intermittently and reduce power consumption.   The following stats are all for a headless, HDMI disabled, RPi Zero W connected via SSH on Wifi. This is using a Purethermal 2 board and a Lepton 3.5 Here are the results:

• 0.098 A -  Idle and purethermal2 is unplugged 
• 0.175 A   -  Idle, now the purethermal2 is plugged in 
• 0.340 A  - There is always a brief spike when the shutter operates 
• 0.250- 0.300 A- When running script that streams constantly from camera
• 0.185A  for 9 seconds, 0.240A for  less than 1 second @ when running script that takes output every 10 seconds

Using exactly the same setup and a Lepton 2.5, the results are almost exactly the same, except it seems like the peak current is a little less ( ~0.23A) and duration of the higher current for running is also less.

I will do this on a headless Rpi Zero W.  

First I am going to install a headless Raspian Stretech lite.  Directions for this are here:

https://howtoraspberrypi.com/how-to-raspberry-pi-headless-setup/

Next I will setup the software for the Purethermal2 to work with the RPi.  I will first install libusb and then the groupgets version of libuvc (https://github.com/groupgets/libuvc) and then I will try the uvc-radiometry.py script from (https://github.com/groupgets/purethermal1-uvc-capture).

Once I get the image capture to work, we will save power by periodically disconnecting from and turning off the Purethermal board which is a usb device.  There are some forums that discuss generally how this is done:

https://www.raspberrypi.org/forums/viewtopic.php?t=134351

Another approach would be to work on doing a better job at stopping camera streaming when we are done.

https://int80k.com/libuvc/doc/group__streaming.html

General power saving tips are discussed here.