My Smart Dummy Camera

I would like to share with you my project, building a camera and some other sensors into a dummy camera.


It started with the desire for outdoor sensors for luminosity and temperature for my home automation system. The best place would be the north side of my house. I considered dedicated hardware but could not find something that appealed to me.

A wall box would be vulnerable for passing scum, so the idea arose to put them in a dummy camera. For getting the data to my home automation system wireless would be the only option. So I needed something to get the data wireless, and that’s when the Raspberry Pi Zero W came into the play. And why not invite a camera module to the party? And perhaps use the Bluetooth functionality, e.g. to control garden IT?

Powering with a battery would be easiest but would need quite some batteries. Of course I did some calculation on the need for current to be expected. I have considered a power bank with a solar panel but could not get it all adequately water proof (ex-ante), including the cabling. So I chose the mains, available in a junction box nearby.

The dummy camera

Smartwares dummy camera

Well, on to searching a dummy camera that could hold a power unit, a zero pi, a camera module and two sensors. The market prefers small and cylindrical, but I needed something boxy and spacious. Long story short, I found the Smartwares CS11D. It’s a simple design that is found under many names but this one has the screws for the top cover on the bottom, so I think it will be slightly better weather proof than others.

Not all screws are willing so some tact is necessary. Inside you find a battery box and a kind of a wall, that on the front side mimics a camera lens and on the back has a small circuit board and some extra mounting points. The circuit board has a blinking led and is wired to the battery box. The extra four mounting points seem to be there for a camera module: it matches nicely, though it could use an extra fraction of a millimetre.

The components

The circuit board holds the led nicely, so I kept it. The smallest capacitor on it conflicts with the camera module though, so I had to remove that and power the led directly through one of the GPIO pins and a ground pin.

Talking about power: that is an issue. I could not find a power unit to build in appliances. I ended up with a power adapter with a USB outlet and a 20 cm short USB cable powering the Zero Pi. I had to demolish the plug to solder a power cord to it, of course nicely insulated with heat shrinks. I fixated the adapter with double-sided tape.

Screws are another thing. You need small ones, really small ones. I bought some King micro-screws online, metrical sizes 1.7 x 8 mm and 1.7 x 6 mm button headed black metal screws, and some brass rings to add spacing. The screws fit nicely through 2 mm holes, and fasten themselves in 1.5 mm holes.

The dummy camera is a metal box with a glass window on the front. That means the onboard Wi-Fi antenna is useless and an external antenna is needed. I found a SMA antenna, a RP-SMA to uFL/u.FL/IPX/IPEX RF cable and a uFL SMT antenna connector. That connector is microscopic and thankfully I found a nearby professional to mount it. The antenna is placed on the back side of the casing after drilling a 7 mm hole.

I fixated the Zero Pi vertically with two pieces of plastic angle profile from the DIY store, 10 x 10 mm, and two screws. As the ribbon cable connecting the camera module has quite some length, I mounted the Zero Pi with its SD card slot towards the camera module.

The two sensors must sense the world outside the dummy camera, of course. The luminosity sensor, a TSL2561,  through a 6 mm hole in the bottom I closed with some rigid fully transparent foil coming from a box of pastry and fixated by a ring of glue. The temperature sensor, a SHT31-D, got a same sized window closed with a sample of mosquito bait. The sensors themselves I mounted to the bottom with two screws and some rings.

For the camera I drilled a 9 mm hole in the front ‘wall’. As the connecting ribbon cable fits into the Zero Pi only one way and the Zero Pi has its ISB connectors on top, I placed the camera module so the text is readable upright. I then removed the protective lens covering (the green tab) and mounted the module with two 8 mm screws. It fits great!

Then I soldered the two sensors and the circuit board to the Zero Pi. Keep in mind that too long wiring is less a problem than too short.

Finally I added the adapter and soldered the mains cable on it. I attached the earth wire to a screw and a 20 cm long USB cable to power the Pi. I insulated the mains and – quite important – assured myself with a voltage meter that the casing is not connected to the mains when the Pi is in service.

The software

I mounted Raspbian Lite headless on the camera, and secured it with Clamav, iptables, fail2ban, cron-apt and logwatch.

For the sensors

  • I enabled I2C in raspi-config and installed i2c-tools, and with sudo i2cdetect -y 1 I checked the availability of the sensors on I2C.
  • I use FHEM as basis of my home automation system, so I installed that on the camera too and linked the camera to my home automation server with FHEM2FHEM.
  • I did sudo adduser fhem i2c and sudo reboot.
  • In FHEM on the camera I
    • defined I2C RPII2C 1
    • defined TempHum I2C_SHT3x, attr TempHum IODev I2C, attr TempHum event-on-update-reading humidity,temperature
    • defmod Lux I2C_TSL2561 0x39, attr Lux IODev I2C, attr Lux event-on-update-reading luminosity
  • In FHEM on the server I defined the dummy modules TempHum and Lux.

Now I can use the sensor data in my home automation rules.

For the blinking led

  • I did sudo adduser fhem gpio ; sudo reboot.
  • In FHEM on the camera I
    • defined BlinkingLed RPI_GPIO 21, attr BlinkingLed direction output
    • defined Blinking at +*00:00:10 set BlinkingLed on-for-timer 0.1
    • defined BlinkOnAtSunset at *{sunset()} attr Blinking disabled 0
    • defined BlinkOffAtSunrise at *{sunrise()} attr Blinking disabled 1

Getting the signal from the camera module to my Synology Surveillance Station turned out to be a project on its own, and will be covered in another post.


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