Home Monitoring System

Interface Alarm Control Audio

This is a redux of an earlier system(s) I have built using the PICAXE to monitor various sensors and triggers around the house.  In all previous cases, the system grew over time as I added new capabilities, eventually maxing out the I/O pins of the PIXACEs I have used.  In addition, as the systems grew more complex, I became concerned with the fact that most I/O pins were going directly to the remote switch or sensor.  I have had very little problem with remote interference impacting these ICs but, there could always be a first time!  So, the new system is designed in a modular form.

The Interface box is designed to isolate the outside world from the PICAXE alarm circuitry.  The picture below, is the inside view that shows the small reed relays uses to provide output isolation and opto-isolators that provide input isolation. The left side shows the top of the box which includes LEDs and push button switches that simulate inputs for testing.  The right picture shows the closed box.


The schematics for all three units are in the dropdowns above.

The master controller unit is made up primarily of an PIXACE 40x2.  This PIC has the highest I/O configuration and I found that I needed most of them!  The LCD screen is mounted in this box and provides a visual of what is going on.  It could be used to modify system function but, without an UPS to provide constant power, any system reconfigurations would be lost with a power reset.


You may notice all of the connectors.  I use connectors for all wiring so I can remove the board, work on it, and reinstall it more easily.

The audio unit includes a Lm386 audio amp and a digital voice recorder.  The recorder is used to "speak" the actual alarm condition and is wired to speakers in the bedroom and the living-room.  This is the fastest way to convey what is happening.   So, if the driveway detector senses a car or someone walking onto our property, the sensor is detected through the interface and routes a closure on the relay driving the amp and recorder.  The controller will trigger the recorder to step through pre-recorded messages to the correct one and "speak" "driveway alert" or "smoke in garage" etc.  The voice message comes after an audible alert signal that is generated by the PICAXE.


Interesting I had to remove the speaker from the box because it impacted the reed relays on the circuit board!

This system has been working flawlessly for three weeks now.  Again, the beauty of the system is that it is modular and I can work on different sections without disturbing the other parts.