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Author Topic: Is remote temperature sensing feasible?  (Read 1605 times)
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Greetings everyone:

Have head of this lovely world you have all been playing in for years now but have been too busy at the day job to dabble...  Now I have a personal "agenda" with the day job that I am thinking could be the perfect place for mixing Arduino into my office gig for the short term to collect some data that I need.  Seems the forum search deamon is not working right now (or maybe I'm such a new user it isn't enabled for me yet but that seems a little ridiculous)

I want to setup a Arduino to monitor temperatures from a building boiler system (one local and two remote) and using a 3 x 16 LCD display all three temperatures and possibly do some calculations on it (energy used - estimated costs etc).  From what I can tell a Lenardo with a 3 x 16 display is probably all I need for the functions (I need three AI's and the serial display output, and maybe a DO for a buzzer), but the wireless wish for the two remote senders is where I'm confused. Wireless temp sending for the two remote points (50 feet away) would be nice - wireless update interval isn't critical as long as it more than say once every 30 seconds or so.  Has anyone seen a project that is cheap and effective with these obstacles?
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Värmland, Sweden
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That's a very common project.
This kind of modules are probably the cheapest option for small amounts of wireless data over short distances:
http://www.electrodragon.com/?product=433m-rf-wireless-module-a-pair-of-receiver-and-transmitter
There are extra transmitters available separately so you can buy that extra transmitter that you'll need.
There's a library called VirtualWire that is quite simple to use.

Search the forum (when it's working again) for virtualwire and temperature and you'll probably find plenty of threads.

Edit: Or use Google smiley
« Last Edit: February 17, 2013, 03:31:10 pm by perhof » Logged

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Thanks for the speedy reply.  While floundering about the web I came across:
http://yourduino.com/sunshop2/index.php?l=product_detail&p=341

Now what I am trying to figure out is if I need Arduino controllers at the transmitting end as well as the receiving (processing) end, or if I only need a micro controller receiving the data and storing / displaying it.  If I can take a digital temp sensor like at DS18B20 and stuff it straight into the transmitters data input would that suffice?  To save battery power I could setup a 555 to power that transmitter every 30 seconds for 5 seconds or something.

Reading up more on the DS18B20 it looks like it needs to be queried to report a temp, which is great for power saving when connected locally... but if I as a total n00b understand this then I would need a transmitter and receiver on each end to close the loop.

So I'll go do some more googling but if I understand this at all if it is at all possible to only use one Arduino I'll need a digital temp sensor that skips that greenie power saving stuff and reports a temp on power up, or every few seconds or something.  Am I way out in left field with this thinking?  If I can keep the remote transmitters to only run on smallish battery and last a while that would be nice.
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Quote
Seems the forum search deamon is not working right now (or maybe I'm such a new user it isn't enabled for me yet but that seems a little ridiculous)

Alternative forum search methods in sig line below.
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Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   smiley-cool

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Reading up more on the DS18B20 it looks like it needs to be queried to report a temp, which is great for power saving when connected locally... but if I as a total n00b understand this then I would need a transmitter and receiver on each end to close the loop.
That's correct, you would need a microcontroller on each end, on that queries the DS18B20 and sends the data and another one that receives and display the data.

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So I'll go do some more googling but if I understand this at all if it is at all possible to only use one Arduino I'll need a digital temp sensor that skips that greenie power saving stuff and reports a temp on power up, or every few seconds or something.  Am I way out in left field with this thinking?  If I can keep the remote transmitters to only run on smallish battery and last a while that would be nice.
I haven't seen any ready-made temp sensors that sends wireless data that can be received by some standard receiver module but that doesn't mean that they don't exist.

I would have built my sensor/transmitter around a standalone ATmega328p running straight from a few AA batteries. The 328p is not expensive and it has some nice power saving modes that consumes very little power. The same is not true for a full blown Arduino since there are other components onboard that consumes power even when the 328 is powered down.
The transmitting microcontroller would be powered down most of the time and you only have to take it out of sleep mode as often as you want to query the sensor and send data so the batteries would last a while.
But building something like that would require soldering and maybe also flashing the bootloader on the new ATmega chip so it might not be ideal as a beginners project.
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Dee Why NSW
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Thanks for the speedy reply.  While floundering about the web I came across:
http://yourduino.com/sunshop2/index.php?l=product_detail&p=341

Now what I am trying to figure out is if I need Arduino controllers at the transmitting end as well as the receiving (processing) end, or if I only need a micro controller receiving the data and storing / displaying it.  If I can take a digital temp sensor like at DS18B20 and stuff it straight into the transmitters data input would that suffice?  To save battery power I could setup a 555 to power that transmitter every 30 seconds for 5 seconds or something.
 
Reading up more on the DS18B20 it looks like it needs to be queried to report a temp, which is great for power saving when connected locally... but if I as a total n00b understand this then I would need a transmitter and receiver on each end to close the loop.
 Am I way out in left field with this thinking?  If I can keep the remote transmitters to only run on smallish battery and last a while that would be nice.

I think you should check the power requirements. A lot of this stuff consumes so little that the 555 may be more expensive. You may find that sufficient control is available from the Arduino anyway.

The radio links you allude to are separate transmitter and receiver. The same source also has the nrf24L01 which is a 2.4 GHz transceiver.

You might also consider using an SD card in order to ensure continued data logging in the event of radio failure. It may even be a power saving dodge!


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