Home automation system. design ideas.

[toftat]

Oh, sorry about that! The main benefit of x10/Insteon is their ability to reuse the powerlines for communication, it is also the source of the reliability problems too (noise in the zero crossing)

If you are using serial communications you should be OK, the only recommendation I would make would be using a balanced protocol on twisted pair (rs-422 or rs-485 I think) to help with interference.

The other thing of course would be to be careful if you are interfacing with the mains voltage. In the US my biggest fear would be fire, but with 220v I think I would be equally concerned with taking a shock. I only mention it because 220v into your hand makes for an unpleasant surprise

[PeterG]

For now, i don't see me needing to switch mains power. I hope the system will run off a couple of low voltage power supplies. I have started on the RGB light inserts for the garden lights. These will be run by a PIC Micro with a 3 channel PWM to control the 3 colors running off a serial line.

I am thinking i may make the light modules addressable so i can select the color of individual lights.

[TechGuy]

Hi,
   I came across this site on a google hit searching for something unrelated. I saw this topic and joined to share some information.

I have slowly been working on a HomeAutomation\Alarm\Sensor system based upon RS-485. I choose RS-485 because if it differential signaling that that isn't sensitive to electronic noise and interference. I've based my design on the PIC 18F6722 MCU. The system is designed to be connected using a four conductor connection; two for power and two for the RS-485 communication. So far I have two modules designed; a Dual Zone Fire-alarm controller and a 4 port relay board. All of the modules will be addressable and can be monitored from a central location. Some of the modules and operate independently with out a master controller (such as a the fire-alarm module)

The Dual Zone Fire Alarm Controller support four wire commerical smoke dectectors (two for power and two for signal alert). The alarm controller supports the commerical remote alarm signalling by reversing the power voltage polarity to force the smoke detector to sound the alarm (this can be used to activate all of smoke detector sounders when smoke is detect on one). Each Zone can be used to narrow down where smoke was detected. I've also included support for combusible vapor sensors that can set of the fire alarm if significant amounts of a flammable vapor is present in the air (proactive fire detection).

The four port relay module always you to control four devices up to 125V @ 5As. The relays are latched so they remain on or off without the module applying significant current to constantly energize the relay coil.

All modules can operate from 18VDC to 55VDC and are designed to use very low power. All modules include system monitor tools to monitor voltages (ie Input voltage, 5V for the MCU and other digital logic, and 12V/15V if the module used either of these voltages). It also has a built in temperature monitor. All modules include overvoltage\surge protection, using TVS avalanche diodes and Gas discharge tube devices. RS-485 Speed can be set from 4800bos to 230Kbps. (Slow speed are required for long distance connections that over hundreds to thousands of yards. Data will be transfered using a simplied packet protocol, where each device is assigned its own unique address.

Other modules are planned but I haven't started them. I just finished the four port relay module last week. Future modules will include a general alarm module to detect intrustion, from PIR, glass breakage detector, door & window switches, etc, Door strike\RFID card swipe (WIEGAND Protocol)\Keypad module, AC power sensor to monitor AC voltage and current, perhaps remote camera controller using an inexpensive SPI\I2C camera, and other sensors. I would also like to add a device switch\hub that can be used to connect multiple ports to a central controller that functions simialar to an Eithernet switch, but using RS-485. I've chosen RS-485 because it can work over much longer distances (up to about a mile) and is much better operating in high electric noise enviroments, where ethernet is limited to about 100 meters, and ethernet can't tolerate a lot of electrical noise.

i've attached a schematic of the 4 Port Relay design and PCB layout for your reference. I am not sure if this project is of interest to anyone. Schematic and PCB was created using Diptrace.

[microherb]

"Wilmot as in Captain Cook Drive, near Resolution Av."

Wow, your close to me Darkman1969, I'm just up the Rd in Crammond Blvd off Captain Cook Drive.

Did you know there is an Electronics design company in Resolution Av, if you worked there you'd be able to walk to work in seconds!

[PetrosA]

I'm going to side with the pessimists. If all you're looking to do is just a few automated things here and there like landscape lights and a driveway sensor, go for it. If you want to do the whole house, talk to a company that install automation systems for a living - if something fails later on, you want to be able to call a technician who knows a system, not second guess a custom design. I definitely agree with Saturation that they can be real headaches - no standards, older systems not supported anymore without a complete upgrade, etc. As an electrician, I'm willing to install some limited automation from well established companies, but mostly I wouldn't want it in my house.

[PeterG]

@Microherb: I didn't know there was a company that close. Good to know.

The system i am looking at building is not very complex. All i am looking for is a couple of temperature sensors and external lighting. I am also playing with the idea of a driveway car detector to trigger a "Door bell type device".

[DrGeoff]

This is something I've been doing for 20 years now. I've always designed my own system, since that's half the fun. If you install it in a modular fashion it is pretty easy to remove when you sell/move.

The first design was a low speed (9600bps) repeated RS232 design, no microcontrollers and simple 8 inputs and 8 outputs per RTU module. I used a COM8017 UART backwards. It was running in a house for over 7 years (then we moved).

Next I went for an 80C51 design with 16 inputs and 8 outputs on an RS485 link at 19200 bps. This worked well for about 6 years until the heat stresses in the roof started to selectively erase the Atmel devices I was using. Re-flashing them brought them back to life. Made a note not to use Atmel devices in this type of system again.

Then I used a PIC16F877 for an RTU with 8 inputs and 8 outputs, 4 analogue inputs and a temperature sensor using the same RS485 link and protocol, which replaced the RTu's using Atmel devices. These sat in the roof of the house for about 5 years, until the house was demolished (yes, I took them out before the dozers came through). The design for this one is available online (http://www.axtsystems.com/index.php?option=com_content&view=article&id=68:rtu401&catid=41:projrtu4&Itemid=73) for those that are interested.

Current design is a PIC18F8722 device and ENC28J60 on a 10baseT ethernet network. These RTU's have 16 inputs, 16 outputs, 4 analogue inputs, temp sensing, 1-wire, counter inputs and 2 serial ports. 5 of these sit on a network (both in the roof and under the house). They connect back to a Linux server which houses the event management system, database and web interfaces.

[DJPhil]

. . . an RS485 link . . .

I've got a warm spot in my heart for RS485.

This sounds like too much fun, I've really got to learn to program in some language or another so I can party with micros.
Right after I finish this project . . .

[PeterG]

DJPhil, i feel i should warn you, when you start to play with micros it will become an addiction. I started several years ago and my life has never been the same......LOL
Now days i look at everything and say to myself 'I can make that work better with a Micro or two'
My wife keeps me from going crazy with it tho...

Regards

[gbowne1]

There are things better than the X10 system.

Consider using a PLC system.. complete with all of the HMI panels, switches, relays, sensors, motors, etc.  There are so many options when you use a PLC for home automation, especially when it comes to HVAC.

They are selling for reasonable prices on eBay.

Consider using the GE FANUC 90-30 system or something like the AllenBradley Micrologix 1500.. or one of the Siemens or even something else.

I'm using a GE FANUC 90-30 complete with a large system but will be switching to the Micrologix.

Greg