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Raspberry Pi Zero W surveillance camera

I needed a camera to take pictures at 10s intervals and I put together something that costs about £30 and gives me full control

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I needed a surveillance camera that would take snapshots at regular intervals. I used a laptop with a webcam for a couple of weeks but I thought this was a technology overkill and decided to build something much smaller to do the job. The process was straightforward to set up but the result is quite neat and I thought it was worth sharing the details. I used a Poundland camera tripod, a junction box from Schneider and a couple of 3d-printed parts.

The mechanical bits

The mechanical arrangement is pretty simple. I drilled three holes on the lid of a junction box, 3.5mm x 2 + a hole of 14 mm diameter. A 3d-printed bracket holds the camera in place using M3 screws. The part prints in some 10 minutes and is good for most camera modules. A different bracked it used to hold the Raspberry Pi Zero W inside the junction box. This part prints in 10 minutes as well. Two more M3 screws are needed there. I drilled an additional hole on the junction box to hold the tripod in place. One of the knockouts was pierced in order to fit the USB cable through the hole.

The software side

The Raspberry Pi runs standard Raspbian. I set it to boot to the terminal using raspi-config and enabled the camera and the SSH service through the applications as well.

You could make the RPi connect to your wifi network but I thought it would be tedious to have to use a keyboard and a screen to log on to the RPi and change the password whenever I changed my router. Therefore, I chose to set the RPi as a wifi hotspot so that I can connect to it from a Laptop and dump the pictures or do whatever I please. The process to set up the system is surprisingly straightforward. You need to install hostapd and dnsmasq. The steps are described here:

https://www.raspberrypi.org/documentation/configuration/wireless/access-point.md

Once I got the wifi setup properly, I was able to get rid of the screen and the keyboard and work on the software from my laptop through a SSH connection. The next step was to set up the camera software. I use fswebcam to capture the snapshots. Detailed step-by-step instructions can be found here:

https://www.raspberrypi.org/documentation/usage/webcams/

When I followed this procedure I faced a little problem: fswebcam complained that /dev/video0 didn't exist. This can be sorted out by loading the proper kernel module by running modprobe bcm2835-v4l2

Most camera modules don't have the ability to autofocus and one needs to adjust the focal length by twisting the lens. This process is tedious if one has to wait to see the snapshots from fswebcam. It is much better to watch a live videostream. This can be done using gstreamer, the best piece of software I discovered in 2017. I believe this is installed in Raspbian by default but one can install it by issuing apt-get install gstreamer1.0 at any time. The TCP video streaming server is started from the RPi by running:

raspivid -fps 26 -h 450 -w 600 -vf -n -t 0 -b 200000 -o - | gst-launch-1.0 -v fdsrc ! h264parse ! rtph264pay config-interval=1 pt=96 ! gdppay ! tcpserversink host=192.168.4.9 port=5000

And from the laptop one can run the following command to watch the video: 

gst-launch-1.0 -v tcpclientsrc host=192.168.4.9 port=5000 ! gdpdepay ! rtph264depay ! avdec_h264 ! autovideosink sync=false

In my case, I made the mistake of pointing the camera upside down, this can be fixed from the client side by adding  "! videoflip method=rotate-180" to the pipeline before autovideosink.

Once the camera is focused properly, one can stop the gstreamer on both the server and the client and set up fswebcam to capture the snapshots. At the moment I'm running this command by manually logging into the RPi but a script can be set up to run automatically on boot by adding the command to rc.local (https://www.raspberrypi.org/documentation/linux/usage/rc-local.md).

Notes about the power consumption of this device

I made a quick measurement of the power consumption of the Raspberry Pi and basically, it takes about 0.08 A when iddle (no streaming), about 0.17 A when running the video stream through wifi as described above and 0.02 A when on halt (after issuing a shutdown command leaving the USB cable connected). This is quite a modest consumption. From my rough estimates, you could easily run the video stream through wifi for about 2 hours by feeding the Raspberry Pi from a £1 USB powerbank (these can fit 0.25 A for about 2 hours). What a time...

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pi_holder.stl

This is the bracket that holds the Raspberry Pi Zero against the case. The model was edited using Solvespace, this is the STL file ready to be passed to any 3d-printing software like Cura.

Standard Tesselated Geometry - 28.01 kB - 10/25/2018 at 13:53

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mount.stl

This is the bracket that holds the camera against the case. The model was edited using Solvespace, this is the STL file ready to be passed to any 3d-printing software like Cura.

Standard Tesselated Geometry - 29.18 kB - 10/25/2018 at 13:53

Download

mount.slvs

This is the bracket that holds the camera against the case. The model was edited using Solvespace

x-solvespace - 273.08 kB - 10/25/2018 at 13:52

Download

pi_holder_assembly.slvs

This is the bracket that holds the Raspberry Pi Zero against the case. The model was edited using Solvespace

x-solvespace - 408.61 kB - 10/25/2018 at 13:52

Download

x-solvespace - 194.80 kB - 10/25/2018 at 13:52

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  • Quick update about real time streaming using gstreamer

    adria.junyent-ferre04/18/2020 at 16:56 0 comments

    The commands I posted in the description of the project work perfectly fine; however, when attempting to stream the video from the camera for a real-time application (e.g. controlling a small vehicle via FPV) I found that piping the output of rapivid into gstreamer added a bit of latency. A much better option is to use the rpicamsrc. This can be obtained from the git page of the project: https://github.com/thaytan/gst-rpicamsrc

    A winning formula that does UDP streaming is the following:

    On the Raspberry Pi side:

    gst-launch-1.0 rpicamsrc preview=false !  'video/x-h264, width=800, height=600, framerate=30/1' ! h264parse ! rtph264pay config-interval=1 pt=96 ! gdppay ! udpsink host=YOUR_PC_IP port=5000

    On the PC side

    gst-launch-1.0 udpsrc port=5000 ! gdpdepay ! rtph264depay ! h264parse ! avdec_h264 ! autovideosink sync=false

     Start the script on the PC side before running the command on the Raspberry Pi.

    I still have to figure out a robust way to handle issues with the connection and restart the video once the link betwen the two works.

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RichardCollins wrote 04/04/2019 at 01:37 point

Adria,

I just wrote to WorstHorse.  I do not know how people cooperate here.  I am just getting started.

And I do not know how to CC comments and messages.  It is a pain to copy things I can barely see.

His SDRs are mostly using USB for sharing the data with the data storage servers. But the chips on the SDRs (an analog radio tuner, and an amplifier/ADC/Usb interface) are readily available and have alternatives, that can be adapted for Pi Zero or ESP, Arduino and other processor boards.

Richard

----------------------------------------------

networked RTL-SDR server - a wifi-based RTL-SDR receiver to cover 1 to 500 MHz

 WorstHorse:

 If you work with adria.junyent-ferre and others who are trying to network sensors and devices, you might be able to rough out some conventions, and share what you have learned. I like her approach. You basically design your SDR as a "sensor", then prepare a data stream that can be shared with others. You might try setting up a nodejs data server somewhere on the network.

 I suggest stick with IP networks to start, as you have done. But it seems ridiculous for you and hundreds of thousands of other developers to keep build the same software hooks just to write your datastream onto some other device.

 I will try to find some framework to make it easier. But you and Adria could at least talk about the broader data sharing needs of sensor data streams.

 Personally, I would like to run ten of your SDRs for several weeks to see what the data is telling me about correlations.
 

 I have been looking for low cost ampliier boards and high sampling rate ADCs (Gsps+). Do you know how to order PCB's? I see them mentioned but do not know where to start. I can probably find and combine amplifier and ADC designs, if I don't have to assemble them myself. From what I hear, they are fairly inexpensive, and I would like to be able to give away some to people who are struggling just go get some data.

 Is there any way I could get you to change the name of your project to read "Zero to 1 GHz"???

 :)

 Richard Collins, The Internet Foundation


  Are you sure? yes | no

RichardCollins wrote 04/03/2019 at 23:55 point

Very nice!  I have many situations where I want to connect basic sensors like cameras, microphones, thermistors, accelerometers and such to a central data storage node. These Zero's could gather the data, communicate wirelessly with host servers to store their results?

  Are you sure? yes | no

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