I'm totally new to this Arduino stuff and I have a some quoestion. I have read a lot of topics and tutorials, so I have a some idea how to program the Arduino and how things generally work.
This is my consept:
The measuring device would have some kind tempature sensor, XBEE transmitter and a 9 volt powersulpy. There would be 5 to 10 pcs of these devices around the house.
Then there would be the dislpay/log device. It would contain Arduino, XBEE, a small screen and some data store device (a small memory card). It would be enough, if the screen could show one tempature at a time. Then there could be a button to toggle between the sensors. I could then do the advanced analyzes at my computer with the logs.
Could it be possible to make something like that? Well I'm pretty shure that the displey/log device is donable, since someone just made similar (see next post) altough it doesn't have a display.
So the real quoestions is what parts to use in the measure device? Is it possible to use just the sensor and a radio device, or does it need more hardware?
Is XBEE the most practical solution for the wireless? Cost is not a real issue, but afcourse if something can be done cheaper and still get the needed functions. I'm also planning to document this project well, that a noob like me could repeat this...
I'm working with a student on exactly that project. We have a protoboard version, with an Arduino connected to a DS1820 temperature sensor, a simple Honeywell humidity sensor and an air pressure sensor, and we're sending the data by XBee. I don't have the base station built yet, but we're getting data on a terminal screen without any trouble. This is definitely a doable project.
There'll be a little more stuff in there - right now I'm adding a second voltage regulator that I seem to have forgotten. You could probably bring the price down a good $10 by using a bare Arduino chip instead of a Pro Mini (which I expect to reuse in other projects). The humidity and pressure sensors are going to run you some money, so you won't get it down too far.
I had some of these parts sitting around already as well, from earlier projects.
I'm not sure if we're talking about the same thing here. I'm not talking about a kit of parts that's available for sale. What I have there is just a list of the parts I'm using to put together into a unit. You'd have to find sources for the parts, and put them together yourself.
You're right about the price - I forgot that you're only measuring temperature. That brings the price WAY down. DS1820s are cheap (yup, $5) - it's the pressure and humidity sensors I'm using that are expensive.
There is one other thing I didn't list that you will need - a board for the XBee. I'm making my own circuit boards for this, so that wasn't a separate part of my costs, but you'll need something to mount the XBee on, some way to power it, and some way to connect the Arduino to the DIN and/or DOUT pins. There are quite a few ways to do that, ranging from the standard XBee shield to various smaller boards that just break out a couple of pins.
It is possible to hook the XBee and a tempature sensor, with out any microcontrollers. Also in the same blog, they have the recieving end built, but it's a bit too simple. Altough the basic components would be the same, Arduino, XBee shield and a XBee.
Do you think that it would be possible to have several of those simple untis and one base unit? Or does the consept of multiple sensor require a microcontroller to the measuring device?
Xbee is definately the most plug and play way to do what you're looking for, but its also one of the most expensive.
you could use an arduino, xbee shield, and xbee module on EACH sensor station AND on the reciever station if money is no issue.
I think i more pratical way might be to use the 315mhz transmitter and 315mhz reciever from sparkfun with an arduino chip, which is what i plan to do with my whole home heating and air zoning project.
your "master" station will send a request for station 1's sensor data and wait for a response. ALL of the stations will recieve this command and analyze the message to see which station it was meant for. when station one sees that the master station's message was meant for it, it will transmit a similar message stating that it is meant for the master, which will then read the message and save the sensor data from station one. Then the masrer will send a request for station 2's data, lather, rinse, repeat =)
the transmitter and reciever will run you $10, a pre-programmed arduino chip and voltage regulator components about $6, and a temp sensor about $6
so that's just over the cost for an xbee alone lol
That sound good. I'l take a look of the transmitters.
Is it so, that I can buy re-programmed chips and then use the Arduino USB Board to program those? And then use the Arduino USB Board as the base station?
If you end up with an Arduino + XBee take a look at the boards I make
that combine an ATmega168/328 and an XBee on a single PCB -- http://wiblocks.luciani.org/ZB1/index.html
The analog sensors can be used with standalone XBees. For longer battery life you
can run the XBees at 3V. Use a Li-ion battery and an LDO. You get about 80%
efficiency during operation and you should be at around 35uA of Icc when
sleeping. I just did a write-up on this. See Loading...
I think I'l try to use the 433mhz units, cause they are cheaper and if I use my own Arduino chip, the cost might stay down and I would have more functionaly.
I red a lot about the ATmega328 and I think my design is ok. Here's a few pics:
Next step is to attach the thermo-sensor, radio transmitter and reciever.
So what pin would be the best for a Dallas DS18B20 digital sensor?
I think I found the right pins for the transmitters. My question is that can I also use ATmega pins to power up the transmitters and the sensor? If I could, then I can preserve power by setting those pins to LOW when they are not needed.
This is my pin configuration:
1 to reset button
2 to RF reciever
3 to RF transmitter
7 to AVCC pin 20
8 to GND pin 22
9 to crystal
10 to crystal
11 power for sensor
15 power for transmitter
16 power for reviever
18 digital for sensor
20 to AREF pin 21
21 to 5v
22 to 5v GND
Can I just use any pin for power, or should I use specific pins? What pin is the correct one for the digital sensor?
I've done some rethinking of the project and I decided to go with three AA-batteries. Those suply 4.5 voltage and around 2500 mAh. This way I can remove some components.
My worry is power consumption. Can you guys provide any power consumption numbers of the Atmega 168 or 328? I didn't fine any from the datasheet or by google.
If I can power the transmitters and sensor from atmega, then I think that their power consumption would be really low, since they would run only when needed.
The digital sensor uses like 2 mAh, but if the update is every 30 sec and the sensor runs only one sec, then the real consumption would be 0,016 mAh. The radious would propaply need to be used longer, so their consumption would be something like 0,2 total.
If the total consumption would be like 0,5 mAh, it would mean that the batteries would last about 6 months. So any idea how much does those atmegas take?