Electronic Design

EiED Online>> Building A Multimedia Home Control Center, Part 4

It's taken me awhile to get this last article in the series completed and the actual installation job is still not done. This is because it entails wiring the house and that is much more difficult than plugging together a PC.

For this next part of the project, we turned to Elk Products that are distributed through SmartHome, which also supplied the Insteon products used in Part 3 of this series. The package we started with is the M1G Home Control System priced at $649. It includes the M1 Control Panel (Fig. 1) and the M1 Cross Platform Control unit (Fig. 2). The kit also includes a number of other items that we will get to later. This provides the base for the system, but each remote sensor or device such as a smoke and heat detector is an item that is purchased separately. We utilized a number of units but only scratched the surface with all the available the options. Some items we didn't get a chance to look at include intercom-like audio system and wireless key entry systems.

The M1G is the kind of system that professionals install when building a computerized home. It can be part of a sophisticated alarm system, as well as a control system that can manage everything from watering the grass to tracking access in a secure office environment.

Elk Components

The M1G alone supports up to 16 zones. This is expandable to 208 zones. It has voice capability (including announcements capabilities) plus a built-in telephone remote-control system. It can drive audio outputs and sirens. It can control multiple devices and track input from even more devices as well, including multiple devices per zone.

The system is modular and easy to use. For example, terminal blocks (Fig. 3) can be added to the end of regular wire. The blocks plug into the control unit (Fig. 4).

A PC can track and control the system. In this case it is our multimedia PC, which communicates with the M1G control unit using the Insteon PowerLinc Controller V2 USB (Fig. 5). The M1G control unit actually has a serial interface, so a second PowerLinc Controller will be found near the M1G unit. The difference is this PowerLinc Controller has a serial interface instead of a USB interface. The M1G can be controlled by and provide information to a remote PC.

The M1G control unit comes in a rugged metal box that is normally mounted on the wall in an out of the way spot like my basement. It needs to be near a power source, and a 12-V lead acid battery is housed in the box to provide power if external power is lost. The battery is automatically charged when power is available and the system can track the battery's voltage.

The system also provides power for the devices connected to the system. In general, these require little current and the lead acid battery is usually sufficient to keep things running for quite a while, but it is always possible to augment this backup capacity if necessary.

The M1 control unit is a dedicated, embedded microcontroller that can also interface to a standard telephone system, accepting incoming calls for remote management and making outgoing calls if a programmed event occurs.


When you're ready to expand your M1 Gold security/automation control system (sold separately), it will be helpful to know that your system will accept up to 16 M1 LCD Keypads. Each keypad features 6 function keys and a two-line, backlit, large-character LCD of 16 characters per line, which displays the system's diagnostics and settings. The LCD's adjustable intensity and extra-large character fonts improve readability. Between its menu navigation keys and its six programmable function keys, programming the display of time, date and temperature is made easy, especially with the aid of a built-in temperature sensor. On each keypad, one zone input and one output are programmable.

Installation Process

If you are new to this type of system then you will probably want to do what I did: Install it on the floor. Essentially, I laid the system out on the floor and wired it up so all the devices were nearby. I could easily check out the device and make sure the whole system was running and controlled properly by the PC without having to run around the house guessing whether the problem was the system, the device or my wiring.

Once the system was running it was a simple matter to disassemble everything, run the wires to the desired locations, and install the remote devices. This is what takes most of the time. The elapsed time is on the order of a couple days although I spread this across a couple months. Your mileage may vary depending upon the type of house, the units you plan to install and what kind of wiring you expect to do.

The job is not difficult and the only tools you tend to need are a screwdriver or two and some wire cutters or strippers. Other tools may be needed depending upon how and where the wiring goes. I have a ranch-style house that tends to be very easy to work with because the attic provides access to all the rooms. I also have a route from the basement to the attic for other wiring. A multistory house can complicate matters and running some wires outside the walls instead of inside may be the best alternative.

In the future, wireless solutions will be good candidates; but for now, a wired system is the cheapest and most reliable. The 802.15.4 and ZigBee technology will definitely change this in the near future, but stick with the tried and true for the time being. A wired approach tends to be very reliable — especially when it comes to security — and there is no need to worry about power supply issues.

The Rhyme And Reason

The M1G system supports three types of device interfaces. The first uses a single wire pair to connect to one or more sensing devices like the 7309 Smoke and Heat Detector (Fig. 6). At $89, these units are much more expensive than the battery powered units found at a nearby electronics store, but the quality and functionality of the 7309 make it worth the price. This is especially true if it is installed in an area that is hard to get to, such as the top of a cathedral ceiling.

As with most sensing devices used in this type of system, the 7309 can be connected in a daisy chain fashion where each device is connected in parallel to a single wire pair. Sometimes the devices require a second wire pair for power, but in this case the same wire pair can be used for providing power and for sensing. This is done by putting a resistor across the wire. A sensor indicates a change of state by essentially short circuiting the system so the control unit can detect the change in current. Actually, a device does not make a real short, but rather adds another resistor in parallel, thereby reducing the voltage on the line while still providing power to each device.

It is a simple and effective approach. Wiring is very simple and usually an external resistor is added at the end of the line as shown here (Fig. 7). Any type of device can be cascaded in this fashion, but there is no telling what device may be signaling an event like a fire. This is why the system supports multiple zones. Often a zone will have one or just a few devices such as multiple smoke detectors for a large or adjacent set of rooms. In this case it does not matter which device signals an event, since it will eventually affect the entire area.

The other type of two-wire interface is simply voltage detection, which is used for devices such as temperature sensors. Only a single device can be handled per line. An extra set of wires is often run to provide power to the device if necessary.

The third type of connection uses a multidrop RS-485 serial interface. This is a low speed interface compared to Ethernet but it provides enough bandwidth for sensor and system control and it allows multiple devices to be individually recognized and managed. A typical system includes the Thermostat RCS (Fig. 8) and the M1 Control Panel. Both have built-in temperature sensors.

Opening the Thermostat RCS reveals the four-wire interface (Fig. 9). One set of connections goes to the upstream system and the other to the downstream system.

Control panel units are only some of the devices that can be in the chain. Expansion units like the ELK-M1XSP 3-Way Interface for M1 Panel: Lights, Thermostats, and Serial Port Expander (Fig. 10) can be used to place interfaces like its RS-232 serial port at a remote point in the system. It can also handle remote voltage-based temperature sensors as well.

There are standard home-control protocols that work over this interface, but you need to make sure that the device you want to connect will work with the control system you have. Some devices, like the ones used here, have jumpers to select different protocols.

Some of the other sensors used in the system included the PIR/Microwave motion sensor (Fig. 11). This one has built-in pet immunity that can detect movement while ignoring small animals like cats. The motion sensors can be used for security purposes or for handling other chores like automatic lighting. In this case it is handy to have Insteon light controls.

One of the other sensors was the carbon monoxide alarm (Fig. 12). It is wired like a smoke alarm but it includes its own controls so it can operate in a standalone mode as well.

Wiring the Home

The first step was to set up the power supply and battery system in the main unit. The next step was to connect it to the serial Insteon PowerLinc Controller V2 and hence to the PC through its USB PowerLinc unit. This allowed the ElkRP software to access the system. I won't get into all the details — the system tends to be rather complicated because of the number of different options available. The documentation is good but it takes a couple of readings and some patience to master everything. That's one reason installers can charge so much, because it does take a level of expertise to do this quickly. Once you have the process down it can be easily installed without doing the gyrations I did to learn how to set up the system. I found it easiest to work on the system at intervals since it was relatively new to me.

The next step can vary depending upon the devices you have and what you want to work with first. I started with the M1 Control Panel and then the RS-485 thermostat since I planned on hooking in my HVAC (Heating, Ventilating and Air Conditioning) system. I already had a three zone system, so it took some time to trace all the wires. Working incrementally, I first tried controlling one of my zones and then eventually replacing the thermostat unit with the M1 Control Panel, which was now wired through the main control system. This entailed some programming through the software so the controls and interface to the HVAC system were linked. The system is not hard to work with but you want to make sure things are configured according to the documentation or you might be a little cold at night. Don't forget to check all the HVAC options or you might wind up needing to do some troubleshooting when the weather changes.

The HVAC support actually turned out to be the easiest aspect of the change since the wires for the existing system could be used for the new M1G-based system. Likewise, the Insteon links made connection to the PC a no brainer.

The hard part showed up when working with the other wired devices. This is what takes a good deal of time since you need to run wires from the M1G control unit to the remote devices. As noted before, having ceiling mounted devices like the smoke alarms was relatively easy with a ranch house where all the ceilings are accessible from the attic.

The carbon dioxide control/sensor is going to be the hard one and I have not done that yet because it must be mounted on a wall about shoulder height. This means getting inside the wall or running the wire up the wall. This is one place where a wireless solution would be very useful.

Over all, doing a dry run on the floor paid off. It was simply a matter of disconnecting a working device and then reconnecting it using the longer wire routed up the wall, through the attic...

You get the idea.

Elk Software

The ElkRP management program (Fig. 13) comes with the system. It is rather sophisticated and can handle multiple homes, control panels and zones. The system can be set up for remote management of a house. Likewise, it can be used once to set up the interface used via the control panels, allowing the system to be used without any PC attached.

The use of the management program does provide flexibility and additional information that cannot be accessed via a simple LCD control panel.

The ElkRM remote management software (Fig. 14) provides a simpler interface than ElkRP, but the two are complementary. ElkRM is designed for the average user while ElkRP is for setting up and configuring the system. ElkRM is priced at $149. Given the cost of the rest of the system, the cost of ElkRM is quite reasonable.

The interface presented by ElkRM is also available via a Windows CE-based flat panel that mounts on the wall. It is priced at $1279 and it has a 7-in. backlit LCD touchscreen.

It has an Ethernet connection and requires a $215 Ethernet port expander for the M1G. The built-in web browser can access the Internet if a gateway is available on the network.

Elk Products is not the only supplier of home control systems but it does have an impressive array of hardware and software. It has dealer programs, training, and a host of other services you can check out at their website. SmartHome provides most of their products to end users.

Investment in a system like this will depend upon a number of factors, like how long you expect to stay in a house. It was definitely the most extensive investment of time I have made for projects I have done for the EiED Online column. The result is well worth the effort. Just make sure you document your wiring and configuration.

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Elk Products


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