Saturday, 14 April 2012

Nano SL5 Alarm Panel

This project came about because my existing alarm system an SL5 Friedland Response Alarm (Honeywell) system had no easy means to interface with it so that I could control it through sms or through the web. It then took off in a direction I wasn't expecting. My initial plan of attack was to interface through the phone port on the SL5 Control panel using an Linksys PAP2. Although I was successful in doing this the interface turned out to be rather clunky as it required a PAP2 plugged to the control panel along with an linux box (O2 Joggler) running asterisk.

So my next (crazy) idea was to see if  I could somehow decode the RF protocol as this would allow me to possible talk to the Control panel or listen to the sensors. Having no experience of alarm systems technology didn't deter me nor the slim chances of dechipering the protocol.

After many months of hardware tracing, constantly staring at bit streams and analysing hex data the dectective work finally paid off. So here is the Nano SL5 alarm panel, possible the smallest alarm panel out there (although not as useful in its current state)! It actually consists of an XRF module reprogrammed with my custom software. This prototype consists of 2 LEDs, the Orange LED indicates the alarm is armed and the Red an alarm is trigged.

As you can see in my test setup I used a Friedland Wireless Keypad to arm/disarm the alarm and a PIR to trigger the alarm. First I have to Arm the alarm using the the Keypad which results in the Orange LED lit.

Next I triggered the PIR, this took some time as the PIR sleeps for 2 minutes between triggers caused by camera movement. This results in the Red LED lighting up to indicate alarm condition.

Finally we can disarm through the Keypad.

Hopefully this now opens up a number of opportunites as the alarm sensors can now be used for other applications. My initial idea is to develop the software so that all sensor information is provide through a serial port. It is also possible to mimic a sensor in order to talk to a real Control Panel. The only downside is that the type of sensors are limited to a PIRs, Door Contacts, Remote Key Fobs, Keypads and an Outside Bell.


  1. So your post on the Raspberry Pi forum, well done must have been hard work cracking the protocol! I suppose the only issue will be the limited appeal with just one manufacturer, but Honeywell are quire large! How does this tie into the Pi then, just over serial and use the Pi as a web interface or something?

  2. My initial plan was just to be able to control my alarm over the web/sms using a cheap board, Raspberry PI fits the bill. So you could either build a Raspi Alarm or just get notification of events. Having developed the interface I think there is probably more uses for example:

    1. Creating new sensors (for example infra-red beam for outside).
    2. Elderly person monitoring, you could detected movement in the house and report if no daily movement.
    3. I also think the Libra+ Door Bell and Spectra PIR (external) could also used although I haven't tried.

    I'd also like to see if I can decoded the following if someones willing to donate sensors:

    1. Visonic PowerMax
    2. FS20/FHZ1000 Conrad Heating controls
    3. Evotouch Heating controls

  3. Would you be willing to share your code?

  4. Will you possibly be making the source code available to the public at all?

  5. where did you get to with this? I'd be dead interested in seeing the source code for the xrf module you wrote as I'm currently trying to learn writing firmware for it myself.