Help with Do-It-Myself automation..


I am a 2nd year electronics engineering student and am very interested in the idea of home automation. I have been toying with various ideas that I have come up with and I recently purchased a Phidget 8/8/8 interface board to start putting some of my ideas to use.

I would like to use LabView as the interface for the automation system and have been playing with some magnetic door contacts and some LM19 temperature sensors, trying to get values showing up in LabView. Everything seems to be working just fine but with only 8 digital outputs, I am fairly limited with the devices I can control.

I have come up with one idea that I would like to try out but I am having trouble figuring some things out. What I would like to do is use the Phidget as a simple interface between the PC and a microcontroller and use the microcontroller to control some of the lighting in the house (on/off and intensity).

If I can develop a communication protocol to send serial data from one of the digital outputs to the input of the microcontroller, then the idea would be I could send a 8+ bit signal that contains an address (ie the light I want to control) and some control bits that contain the light intensity (for dimming lights). For example, to start with, I could have 2 or 3 bits for the intensity which would give me 4 or 8 levels of brightness, and 5 or 6 bits for the address which would give 32 or 64 control lines. The microcontroller would output the intensity as an analog voltage along with the address bits to a demultiplexer that would fire the voltage off to the correct light.

What I would like to find out from you guys is:

1) Does this seem too complicated? Would there be an easier way (still encorporating the Phidget)

2) What is the safest way to actually control the lights? I've been toying with the idea of using a voltage controlled Triac circuit. Could this be installed in the existing light switch boxes?

The reason I am doing it this way and not going with a prebuilt system is mainly about the money but I think I would also learn a lot building it myself. I have not had the power electronics course at school yet but I have programmed Microchip microcontrollers and Alterra CPLDs and have lots of experience with multiplexing, ADCs, DACs etc.

Sorry if this is too long but I have all of these ideas and I figured you guys would know best ;) . Any help you can give would be wonderful. I love this website!
Hi Squiddy, welcome to CocoonTech!

Is there any reason you aren't interested in using X10/Z-wave/UPB to control your lights? One other solution I would look at is the Ocelot, it is a stand alone hardware device which has a rs485 bus, so you can add more modules (such as a SECU16 which provides analog/digital inputs and outputs), and also supports the X10 protocol. I like the phidget stuff as well, but I am not sure if it is the best tool for the job in this case.
Welcome to the board!

I hate to sound so somber, with this being your first question posted and all. But, I have to say, I agree with Electron here.

As an electronic student, I can see where the fidgeting and being able to completely do it all your self is inticing.

On the other hand, you are talking about creating your own protocol, coils and devices to dim ect. Sometimes re-inventing the wheel is not always the best option.
Biulding your own light switches is possible, but it would also involve running wire to every switch in the home to control the switch via serial as you mentioned.

As for saving money, you might be supprised just how low cost you can get into controlling your lights. X10 devices are pretty inexpensive. You can get hardware to control 9 devices by both your computer and with a remote for around $50. Check It Out Here Which is probably less than you would pay for the parts needed to build your own system.

Its hard to beat the reliability of many of the off-the-shelf products. For instance, purchase any X10 / Zwave wall switch, and within a minute, you can control the light with a multitude of different remotes. With a computer controller (X10 CM11a, USB Zwave and a host of others) you now have complete control of your light from the computer. Such as scheduling, dim levels, and in many cases 2 way communication so the computer knows what the status is, off, on, dim level ect. All capable of controlling upwards of 256 devices.

I currently use a program called HomeSeer. With it I have touch screens, portable tablet PC's, remotes and computer control, motion activation ect, of all the lights, phone, security ect.
He stated:
The reason I am doing it this way and not going with a prebuilt system is mainly about the money ...

When I was in college I couldn't have afforded an X10 switch let alone a z-Wave one. ;)
I assume by prebuilt he means systems such as Creston. The phidget hardware isn't cheap either, and neither will be the hardware components needed to build your own switches.