Awesome! But until they are for sale for cheap, I’ll have to continue designing my own.

This would be useful to people who have wine cellars, green houses or anything else that requires monitoring.

This could also help reduce heating/cooling costs in your home. Don’t know about anyone else but there is always some part of my place that is either too cold or warm and I don’t always notice it right away, this would help.

@johannes burgel:
ehh- right. it’s only useful once the information is used to actually *do* something. for example having an actuator open a basement window based on in- and outside humidity and temperature.

I’m currently also working on something like this.

I’m using mainly attiny45s’ and attiny13s’ for the sensors and an arduino for the main controller (hey its still in the prototyping phase!).
I’m using hopeRF 868mhz radio modules for comnmunication, so my 4 AAA batteries are only expected to last 3 years.

My main incentives are:
- Restart my server if it doesn’t respond to ping for more than 10 minutes.
- Being able to start/stop servers when i’m travelling and need to access some files.
- Having an “all off” switch next to the door, if i have to leave in a hurry
- Being able to switch off the various home entertainment equipment from my bed
- Adjusting the temperature over night to have a comfortable environment (my bed is relative far from the radiator, and since i’m using long distance heating, my radiators heat varies over time)
-Generally monitoring my energy usage, room temperature, etc over time

I’m also able to control various devices (lights, fans, monitor, computer) via a small infrared remote, and one goal is to integrate my self build alarm clock into the system to have it start a few devices automatically when i get up.

At my url you can see a preliminary web frontend for the system, not everything is done yet. And you will only be able to switch on two lights, to avoid irritating me.

Hello NsN,
your project appears really interesting.

- do you have an ongoing thread / wiki / homepage?
if not,
- can you give further information regarding the hardware / rough schematic or used parts
- cost? again, just an estimate
- did you publish any code?

I would be willing to help you in improving the attiny45′s firmware. I already did some projects with the attiny25 and the powermanagement can be quite tricky.

The explosion in DIY home automation will happen when the Bluetooth Low Energy single-mode chips to appear – they’re insanely low current draw, have the same range as Bluetooth, and will have all the features of current non-wireless micros…

@avion23

Thanks, it’s nice to get positive feedback.
I haven’t really published anything yet (code, schematics, etc) since everything is still pretty much work in progress.
Especially the code is still very ugly. But i can post the schematic / board layout for the sensors and the arduino shield later today.

Cost:
I try to keep everything cheap. The most expensive part are the RF modules at ~5 EUR, i would love to replace those with something cheaper, but haven’t found any good alternative so far.

Rough Estimates
Temperature Sensor:
Attiny45 (a Attiny25 would also be enough) – 1.50 EUR
RF module – 5.00 EUR
a NTC Resistor, a diode, a few resistors… – 1.50 EUR
= 7.00 EUR in total

Arduino shield:
RF – Module – 5.00 EUR
IR Parts – 2.00 EUR
Opto Couplers – 2.00 EUR
Bits and Pieces – 3.00 EUR
= 12 EUR in total

Arduino + Ethernet shield = 58.00 EUR

Remote controlled outlets:
3 for 9.99 EUR

IR Universal Remote:
9.99 EUR

RF Radiator knob:
25.00 EUR

Just some rough overview, my aim is to have the base module with a few temperature nodes and a couple of outlets below 100 EUR.

In the future i want to transition from the Arduino to a bare atmega 644 and then probably to an beagle board. this way i could have the server run on the controller directly.

If i ever become satisfied with the current state, i will definetly make a writeup / explanation page and submit it to hackaday and post it on the arduino forums.

@Andy
I agree that my system is currently vulnerable to all 3 of your points, but it doesnt have to be.
There are currently only 3 reasons holding me back from using a full public key encryption on the protocoll:

Cost:
I’m using cheap remote controlled outlets that are not encrypted, because building my own would be at least twice as expensive, and wouldn’t have such a nice enclosure.

Time:
My protocoll is still very basic because it is still in the prototype phase, i only have a crc16 checksum at the moment.

Ease of debugging:
It is very usefull to be able to read the data transfered by just starting a rf reciever and dumping the output straight into putty.

There are optimized cryptography routines / libraries out there for microcontrollers. Since a wireless sensor usually spend 99% of its time sleeping, i imagine that it would be possible to encrypt the traffic for anything but extremly low power devices.

I believe the bigger danger lies in the webfrontends. If people use simple passworts, even the best encryption won’t help them.

One other “issue” 27MHz sits in one of the HAM bands, one of the reason BPL was fought hard against. Even low power can cause problems not to just HAMS but to EMS services as well. Those frequencies go out over the power lines and radiate from there, it doesn’t take a lot of power to cause interference.
Also unless you install bandpass filters to block the signals what’s to stop someone from hacking backwards through your own wiring as well.

27 is a bad choice. Not because it’s an amateur radio band, but is used For Citizens Band. When propagation is hot those flea power transmitters wouldn’t stand a chance. Anyway why use RF at all? Mount the sensors next to a receptacle and use the house wiring to carry the data directly. The low data transmissive rates shouldn’t cause interference or very low RF frequencies could be employed to keep operation from more used RF spectrum

car car redundancy oops =/

sorry error, using powerlines as an antenna is as old as power lines and radio

problem is it turns your house into a small noise transmitter that hacks off the grumpy old ham down the street (who are strong and old enough that when they gripe FCC listens and we don’t reap the benefits)

otherwise it would be 100% common place, and IS common place in certain areas (tv antenna’s bug be gone ect), and as grumpy old hams loose more “get off my lawn” space you will be seeing much more of it, such as ultra broad band internet, which is 15 years old but JUST NOW coming into service in select areas (like over 1000mb both ways for less than 400$ a month)

and yea its not that complicated of a board, though the exact mathematics of the specific system may be (just due to the fact that radio is a pita)

@Osgeld

The same authority that protects the “grumpy old ham down the street” protects the spectrum space (and therefore the functionality) of YOUR cell phone, YOUR garage door opener, YOUR wifi, YOUR digital broadcast television, YOUR AM and FM radio stations, YOUR wireless alarm system, YOUR Sirius radio, YOUR bluetooth headset, YOUR GPS, your FRS radios, YOUR wireless keyboard, on and on…

YOU enjoy the “benefit” of these services only because agreements have been made with regard to the frequencies they will operate on, and penalties have been established for those who don’t observe the rules.

You want to eliminate the ability of the “grumpy old ham” to complain about interference to the ham bands? Go for it. I guess you won’t mind then when I disable your wireless router by keying up on top of it. Imagine trying to call an ambulance on behalf of someone you love and find that you can’t– because someone else’s carrier is stomping all over yours?

I strongly suspect that you would suddenly find that you have a lot in common with the ham and his perspective.

Honestly, there are a lot of signs of the impending collapse of western civilization, but the unabashed advocacy of carelessness and selfishness seems to rank among the most prolific.

MOST of the wireless automation systems, like one mentioned here, do lack security implementation.

I for one do not want to let some script kiddies to hack my house.

“Let me consider your post script. 600,000 licensed radio amateurs, and to a lesser extent, 3 million hams world-wide, should abandon a century-old communications medium because you are “pissed to no end” that your porn downloads too slowly?”

and we should not progress cause 3million hams want to broadcast 9600 baud packet radio, crap tv, and think its neat to talk to someone in England? all the while sucking up MOST of the spectrum doing it?

“Like I said… selfishness.”

exactly

@osgeld said:

“and we should not progress cause 3million hams want to broadcast 9600 baud packet radio, crap tv, and think its neat to talk to someone in England? all the while sucking up MOST of the spectrum doing it?”

You claim that you are a life-long subscriber to QST. Helpful hint number one: “Subscribing” is not the same thing as “reading.” If you had actually read QST over a “life-long” interval, you might have learned something.

On the contrary, it is apparent that you know nothing about frequency allocations, RF propagation, transmission lines or antennas, and more importantly, you know absolutely zilch about information theory.

Ok, suppose you’ve waved your magic fairy wand and all hams have disappeared. Just how many gigabit broadband channels do you figure you are going to fit into the 500 kHz wide 80 meter band? How many in the 300 khz wide 40 meter band?

All of the HF ham spectrum space *combined* is less than the bandwidth of a *single* channel of analog video. Sorry, that’s not “most” of the spectrum. It’s not even a tiny sliver of the spectrum. But then, don’t let me burden you with facts.

Seriously, dude, if you have some obsessive hatred for hams, that’s your business… more power to ya. Your arguments, on the other hand, display a fundamental ignorance of the subject.

If you have a relatively new AC unit (made after 2k8) then its probably able to monitor the weather conditions in your house and set the temperature accordingly or dehumid the air etc. only impressive thing about it is its able to work for 10 years.

Also you can get loads of alarm clocks under 50$ with temperature sensors.

@error404: thanks, I was about to say the same thing. I don’t know where you people live, but in my area basements definitely don’t have the required equipment to build a custom silicon chip.

heck I remember when that tiny little cable coming into my tv would only provide 13 channels and I still needed an antenna

now that same wire allows me to stream dvd quality movies while my wife plays a online game and streaming cd quality music while the kid watches HD TV in the other room over a few hundred channels

its called progress, Imagine if we still did things like we did a century ago, it would take a month to make a 20 min drive, that is what you argue for, for the sole reason of “that is how we did it a CENTURY ago and 3 million people world wide still choose to do it that way

sorry but I moved on a long time ago, go spin your own yarn and ride your 2 horse carriage

@ Eirinn.. the actual question is , was there ever ham in spam?