Temperature Monitoring

[desperate]

Still stumped

Desp

[Greenbeast]

desp - i've figured out enough of the technical stuff to set you up

i've got an arduino with LCD showing temperatures from 5 1wire sensors, but i could easily show more sensors

[desperate]

GB

Cool, maybe you would be good enough to show me how to set it up

Thanks

Desp

[Greenbeast]

yeah no problem

I'll just get the details together and i'll post it up

[Greenbeast]

The hardware used for this project is:
-   An arduino – i bought a freeduino (http://www.nuelectronics.com/estore/index.php?main_page=product_info&cPath=1&products_id=1)
-   LCD screen – i used this one (http://www.nuelectronics.com/estore/index.php?main_page=product_info&cPath=1&products_id=12)
-   A number of 1wire sensors  - i bought 5 of these (http://www.nuelectronics.com/estore/index.php?main_page=product_info&cPath=4&products_id=5)
-   A resistor around the 4.5-5kOhm range ( i had a couple of 10k that i put in parallel)
I also used a breadboard and some jumper wires with pins to get it set up, but you shouldn’t need to.

Software needed
-   The arduino development environment (http://arduino.cc/en/Main/Software)
-   This 3310 LCD library (http://blog.thiseldo.co.uk/wp-filez/nokia_3310_lcd.zip)
-   This dallas 1wire library (http://download.milesburton.com/Arduino/MaximTemperature/DallasTemperature_350.zip)
-   This code example (http://goldengolf.pwp.blueyonder.co.uk/Temp.rar) - i’ve modified and stripped down the original example code to just show the result from 5 x 1wire (D18B20) sensors

-   Install the development environment and extract the libraries to the arduino\libraries folder.
-   Extract the code example to the arduino\examples

-   Hook the sensors up using post 2 of this thread (http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1233882140)

-   Plug the lcd shield onto the arduino
I currently have the sensor wires wedged into the same holes on the arduino headers as the lcd screen but i’m using pins that aren’t used by the screen.
This isn’t my long term solution, i’ll probably snip the unused lcd pins off and use some right-angled header pins to connect my sensors

Open the development environment and import the new libraries, open the code example and upload it to the arduino.
It should reset and run automatically

I’ll try and answer any questions i can!

[mpooley]

I wonder has anyone tried these EZ430-RF2500 thingies?

 http://gb.mouser.com/ProductDetail/Texas-Instruments/EZ430-RF2500/?qs=sGAEpiMZZMuIes%252bYBRf57doByqsimH2mSXkc1d38WKU%3d

looks a very easy setup and not Tooooo exspensive.

I believe you get the master that connects to the PC and one target board with battary box in a kit.
This is wireless so much easier to install and each new target board (eg the actual temp sensor) is only £15 which seems very reasonable to me, for a wireless sensor.
AS I understand it the target board comes allready kitted out with two temp sensors and you can more or less add any other type of sensor to it. ( I dont understand it all that well  yet!)
so you could set up a complete home temperature network with no wires!

can someone with more brains than me have a look at this and tell me if i'm right?

I am very seriously thinking of splodging some ackers on this 

Mike

[Greenbeast]

Video evidence of my above post:

http://www.youtube.com/watch?v=t8GXNnWMUec

[marktime]

I ordered one of these as Eric suggested it was so cheap it would have been rude not to. It arrived a few days a go and is being put to use checking that the fridge & freezer are set correctly it will then go in to monitor hot water tank temps. clearly it's a manual process but it's a start.

For a really cheap solution try a whole bank of this type of thing

 http://cgi.ebay.co.uk/Digital-LCD-Thermometer-for-Refrigerator-Freezer_W0QQitemZ320433266103QQcmdZViewItemQQptZUK_Gadgets?hash=item4a9b4f9db7

If you were short of display space, you could cut off the sensors from all but one and connect via a switch to the remaining display. As I expect they use themistors (large resistance change with temperature) you would be able to extend the sensor cables without too many problems.
Stupid as it seems I bet the replacement batteries would cost you more than the whole item.

Stop press the price has gone up by 3p, now £1.72!

[Froggs]

Video evidence of my above post:

http://www.youtube.com/watch?v=t8GXNnWMUec

Impressive! I'm new to this forum, stumbled across it via google. I'm not an electronics expert, OK with electro mechanicals & engineering & plumbing etc..  I have been trying (researching) wanting to do do much the same as 'desperate' and had concluded that given my requirements and limited knowledge (of electronics & no prior experience of PIC/ microcontrollers) that I would have to resort to using PICAXE and DS18B20s and LCD multiple displays... (I can just about cope with the basic....although in days back I was something better at RPG!).. for some reason in my original research I had discounted the arduino;   I had also experimented with the cheap thermistors... but extended leads presented too great resistance...

I like greenbeasts video evidence & the detailed posting instructions... I'll study them a bit more. But along either greenbeasts approach or my original thinking what  I want to achieve from an outcome perspective  is:

> Multiple remote sensors (probably 8 pairs (flow/ return) ie 16 in all
> Each pair of sensors output displayed (with constant) on top/bottom row of 2*16 lcd display (ie 8 lcd displays in all)


I don’t want to reinvent the world by adding to this post.. but if someone could point me to better understanding how to link multiple DS18B20s with outputs displayed 2 per LCD.. either using PICAXE (or arduino) that would help.

Thanks.

[Greenbeast]

Using my method you could easily show 16 temperatures.
The 1wire bus should with that many slaves although i'm no expert

The solution i use could be used to display as many temperatures as you like. If you were to go that route i'd have a menu showing two options, you can then select to view the firs 4 pairs and then the other option can show the final 4 pairs.

check out the actual project i'm working on :
http://www.youtube.com/user/Greenbeast999?feature=mhw4#p/a/u/1/Bzjp8KM3nvc
this shows something closer to what you might want

i can easily help you knock up the code for it

[Froggs]

Using my method you could easily show 16 temperatures.
The 1wire bus should with that many slaves although i'm no expert

../ ~
i can easily help you knock up the code for it

Thanks. Agree that your method will work! I am just keen to ensure that I achieve 2 things.. the end result AND an understanding of how I got there (intellectual stimulus)  perhaps that is why I steered towards picaxe.. it just seemed easier?

Many thanks for helping to knock up the code... it will probably be required. I guess if anything is not basic oriented... then I would have severe limitations. I'll investigate your previous posts & reply back here... but any other idaes or approaches always welcomed.

Thanks again

[ericw]

Froggs,

I don't think your idea would offer the best practical solution.

To read 16 sensors you have basically 3 options
 a) use 16 i/o pins with one sensor per pin
 b) use an external multiplexor - 5 i/o pins
 c) Put all the devices on one bus and address them individually via their ROMID address.

I'm not familiar with the built in functions available in Picaxe basic but its possible there is already coded a function to read a single sensor you could use for a) & b).  For c) you could either hard code in the ROMID's or code up a Search ROM routine (algorithm is on the Maxim-ic website) to scan them.

To drive multiple 16x2 displays again you would need a large number of I/O pins even if you used an external multiplexor to select the appropriate display.
I would suggest that a more complex display would be a much better option - you could squeeze in 16 readings on a 20x4 display (just) which uses essentially the same driver code as the 16x2. You could alternatively scroll a smaller display, or you could go to a pixel orientated display similar to that used by Greenbeast.

If you want to stick with Basic and PIC's then the Basic compiler from Oshon has built in functions to read DS18B20's and drive LCD displays, but as it doesn't have the Picaxe 'self programming' environment you would need a programmer.
 
An alternative is to do as Greenbeast did and go to the Arduino environment which is pretty Lego like for both hardware and software.
 If you compare the total cost, rather than the pure chip cost, then I suspect there would not be a huge difference.

[Froggs]

Ericw

Thanks for your input. I’m learning fast.

Inputs. With regard to approach my understanding was that (c). ie one wire bus & addressable devices; I had assumed hard coded addresses, but useful thoughts about searching.. more research for me!

Outputs. I had appreciated that I would need multiple i/o pins..and could utilise i2c and slave chip (is that the correct terminology) although I still don’t understand quite how to construct the code to do this [output wise]; or alternatively there appears to be use of Picaxe firmware FRM010 at c£5 a pop http://www.rev-ed.co.uk/docs/FRM010.pdf and http://81.134.141.187/epages/Store.storefront/?ObjectPath=/Shops/Store.TechSupplies/Products/FRM010 which given my illustration would require a [summary] kit list of picaxe chip, 8*frm010, 8*lcds.

Or am I missing a trick? I still have to research Greenbeasts solution further as while you remark its lego like; ive not got to grips with it yet. From another perspective while there appear to be a number of approaches that will actually display the temperatures (eg using menus, scrolling, squeezing to fit etc) my conception was to be a ‘nice’ box with clear ready to read displays.. no user intervention/ interpretation.

Thanks both for your contributions. Any more ideas (or help expand continuing thinking) welcome. It’s the weekend now… so more research now & I’ll post back soon.

[Greenbeast]

i'm close to finishing mine off in a project box with my sensor on looms.
I will post some pics when i'm done.

Your project could be in a nice box and like i said you could display 2 (or more, it'd be expandable both in terms of code and number of sensors) pages of temperatures with a simple menu, i think this would be quite a clean install and interface

[Froggs]

I'll keep watching.. thanks!