Alarm system and SmartHome

Reading time 3 minutes

Updated – January 20, 2023

The topics of alarm systems and SmartHome are often found together today. Whether Alexa wakes you up, reminds you of an appointment, turns down the heating when a window is open or you lock the door remotely, these are all actions of SmartHome technologies.

So why not use SmartHome as an alarm system?!

Whether a window contact controls the heating valve, initiates an email or activates a loudspeaker announcement ultimately remains the same.

Components

What components do you need to implement an alarm system using SmartHome and how do you plan it?

First, create a list of all the windows and doors that need to be monitored, including basement or roof windows.

Then you think about whether a silent or acoustic/visual alarm or cell phone notification should be triggered.

If necessary, it makes sense to provide an emergency power supply in order to prevent sabotage, for example by short-circuiting the neutral and earth conductors in order to trigger the FI switch.

Where is the burglar?

If you are at home at the time of the uninvited visit, perhaps simply asleep in bed, you might want to know where the uninvited visitor is, if the worst comes to the worst.

Motion detectors installed in the corner of the room near a window, opposite the room entrance door, are suitable for this purpose. So if he comes through a window, he has already been recognized and reported; if he comes through the door, he is also already detected as soon as he has noticed the motion detector.

This makes it possible to track where the perpetrator is either on a cell phone, tablet or by email. After all, who wants to unexpectedly find themselves face to face with the person in their pajamas?!

Shopping List

• Window and door contacts (optical, battery operation possible)
• motion detector (with crawl-under protection, battery operation possible)
• speaker as a siren, doorbell or status indicator (operated via 2x mono cells)
• Dialer (Emergency call, 10 numbers each SMS / call)
• Raspberry Pi4 Model B
• Case for Raspberry Pi4 (incl. power supply)
• SD card 32GB for Raspberry Pi4
• Homematic transmitter module for the RaspberryPi (finished device, not a kit!)
• Emergency power supply APC 900 VA (UPS for Raspberry Pi4, dialer, etc.)
  
  

software

In order to be able to put all components into operation, you still need the constantly updated RaspberryMatic software from Jens Maus in the current version for the Raspberry Pi4. This can be downloaded for free here receive.

Clicking on the Download button leads to the download overview. You can find the section below Download and the different versions available. The version required is the one for Raspberry Pi4 Model B, which is provided in the form of a ZIP file.

Additional software to create the image file for the SD card is required and will be here for Windows and here also available for download free of charge for Mac OS.

Software installation

The installation via one of the two imagers is self-explanatory. First you select the image file (included in the ZIP file), then you select the SD card to which the image should be copied, finally you start the copying process and wait until the image is written to the SD card and it was ejected.

The image contains the boot partition and the RaspiMatic program, through which all of the above components can be integrated, managed and programs created.

The SD card is now pushed into the SD card slot of the Raspberry Pi4, with the contacts facing the board until it clicks into place.

Hardware installation

The Raspberry Pi4 circuit board is installed in the housing and the Homematic radio module is plugged flush into the front of the Raspberry Pi4 post strip.

The fan supplied with the case is screwed onto the top cover of the case from the outside so that it transports the air out of the Raspberry Pi4.

The plugs of the fan connection cable are cut off directly above the plugs. The cable ends are stripped of about two millimeters of insulation and tinned. Before ventilation, both cables are routed inside through the narrow housing cover slot. The black antenna cable finds its way out the same way, or more elegantly via a 2 mm hole in the bottom right corner of the fan housing.

The red cable is soldered to pin 1 + 3.3 V (the first internal pin) on the radio module, and the black cable is soldered to pin 6 - ground (the fourth external pin). This is seen from the SD card slot.

connections

For commissioning, only the power supply cable and the network cable need to be connected. After switching on the cable switch coming from the power supply, the Raspberry Pi4 boots, which can be seen by the red and green flashing status LED of the Raspberry Pi4.

access

The Raspberry Pi4 starts in DHCP mode, which means the IP address is assigned by the router. The assigned IP must first be found on the router's website and then entered in the address bar in the browser.