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Author Topic: No frills low cost standalone 1 wire datalogger  (Read 42670 times)
ericw
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« Reply #15 on: October 14, 2010, 10:51:44 PM »

Comments on the various points raised.
Ethernet shield
The driving force behind what was done is mainly my personal requirement. As I have a wireless network and the nearest hardwire connection is on the other side of the house I don't have any real incentive to go in that direction, especially as a wireless bridge would add significantly to the cost. However you might be able to persuade me with what I'm missing out on. Having said that It ought to be possible to replace the card access routines with ethernet access ones to get whatever functionality you are wanting.

Parasitic power.
The software is set to drive parasitic devices by having a low impedance high state during the convert stage, using powered devices would have no adverse effects and there is some evidence around to say for the lager number of sensors its better anyway.

Instructions
From what point would you like me to start?   The standard instructions for installing the Arduino environment seem pretty comprehensive, probably better than I could do them (but I almost certainly have a rather distorted view) and if you got stuck help would be available on the Forum. If you get to that point then I can document the rest quite easily.

As regards cost I agree with KenB that the bits and a DIY board are much cheaper but I'm both lazy and would like to try and benefit a larger audience than the few who can build & debug their own circuits. An off the shelf Arduino seems to be good compromise between cost and convenience bearing in mind that only one per system would be used.

I did seriously consider the Stalker, as the cost is pretty well the same, but as I only have USB ports on my machine, the balance was tipped in favour of the present setup. On the other hand as the Stalker doesn't have the USB interface its supply current could well be low enough to make battery power more feasible.

I'm looking for suggestions on improvements for the MKII version.
The system will start in standalone mode by just turning the power on but it would be reassuring to have some indication that it is working correctly, at least for the first measurement cycle.

I think that maybe linking the sample time with the time per file, eg one file per day @ 1 minute intervals or a monthly/weekly one at 5 min intervals. This would keep the size of the files reasonable for subsequent processing. It could be switched using a jumper on the digital pins to save having to recompile & upload.

I could add the ability to read DS2423's counters but handling more outputs than ROMID's has some implications at the analysis end.
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stephendv
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« Reply #16 on: October 15, 2010, 09:55:06 AM »

Eric, interesting point about the stalker not having USB, I didn't see that.  So you'd need an extra 10 quid adapter to talk to it, which means the nuelectronics shield starts becoming cheaper a option.

Klaus, PoE ethernet shield from down under: http://www.freetronics.com/products/ethernet-shield-with-poe
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KenB
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« Reply #17 on: October 15, 2010, 12:03:57 PM »

Whilst on the subject of 1-wire

I came across Sure Electronics who do a nice stainless DS18B20 temperature probe for about 3.50 on a 1m cable terminated in a 3 way JST female connector.  ( I think that's compatible with NuElectronics shield) - but easy enough to interface to if not.

http://cgi.ebay.co.uk/Digital-Thermal-probe-sensor-DS18B20-/350403450214

They also supply a wide range of electronic components and displays direct from China - at keen prices. Free postage to UK.

Additionally they do a "flexible" low cost pcb prototyping service - check seller's other items for details (some Chinese pcb services were fixed board size).

http://cgi.ebay.co.uk/Low-Cost-2-Layer-PCB-Manufacture-Service-2-25-boards-/350191489301?pt=LH_DefaultDomain_0&hash=item51890a1115



Ken
« Last Edit: October 16, 2010, 10:33:07 AM by KenB » Logged
Baz
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« Reply #18 on: October 15, 2010, 02:46:58 PM »

the nuelectronics connectors are JST-XH like this
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=5469066
Which seem to be used in Radio Control kit and batteries and are rather hard to come by except as made up leads. I can't find the other half on RS at the moment.
Other 2.5mm pitch can fit but it would have been nice if they'd used the more common molex standards.
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Baz
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« Reply #19 on: October 15, 2010, 04:26:12 PM »

found 'em
cable housing is JST XHP-3 and pins SXH-001T-P0.6
http://uk.futureelectronics.com/en/Search.aspx?dsNav=Ntk:PartNumberSearch|jst+xhp%2f-3|1|,Ny:True,Nea:True

although it says uk I thinkit may be shipped from USA so 2p for product and #20 for postage.
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Baz
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« Reply #20 on: October 15, 2010, 04:46:45 PM »

Wonderful what you can do at work while on a conference call,
3 way connector housing RS part 353-1620,
4 way 3531636
crimps 353-1591 ( JST part BXH-001 not SXH as above)

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wookey
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« Reply #21 on: October 19, 2010, 02:28:18 AM »

What makes you think they are JST-XH? (which I agree are a pain to source - the really handy hobby city celllog8M uses the 9-way version too so I had to look recently). The pic at the ebay link Ken gave shows what looks like bog-standard molex 0.1" header to me and says "3-pin 2510 Female Header Housing" which also suggests to me a molex part. Have they changed the description/pics since when you looked?

And I can't see a diameter listed either which is tiresome. Will they fit in the 8mm ID holes in chinese ET panels? Nice format though - they are the first encapsulated _powered_ 1-wire sensors I've seen. Every other encapsulated device to date has been 2-pin, which is a deal-breaker for me. And a good price.
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Wookey
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« Reply #22 on: October 19, 2010, 06:50:54 AM »

Wookey,

Since my first posting about the stainless sensors - please note that +5V and 0V would need to be reversed to make them compatible with the NuElectronics board.

Diameter <5mm.



Ken
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StBarnabas
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« Reply #23 on: November 12, 2010, 01:14:56 PM »

Eric

As you may be aware Desp is staying at StBC,  plumbing in my 1000 Litre thermal store FOC. In return I have offered my expertise (such as it is) in data logging.

It looks as if he is only interested in measuring temperatures and would prefer not to tie up a PC but still be able to log data and look at readings.

Most of this is already there with your Mark I version but with the addition of a Nuelctronic LCD shield:  http://www.nuelectronics.com/estore/index.php?main_page=product_info&products_id=12   one could display the temperatures and scroll down through the sensors using the joystick. For an extra 10.00 this would be a very useful addition and I may well have a go at doing this over the next few weeks. Does this sound like a good plan?


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ericw
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« Reply #24 on: November 12, 2010, 04:02:15 PM »

Sean,

Yes I think you can just stack the LCD shield on top to both display the results and datalog them for later. They are using digital10 as the LCD chip select which is probably why the SD shield CS was moved to digital5.

'Greenbeast' has previously described a similar display here http://www.navitron.org.uk/forum/index.php/topic,9852.msg109978.html#new

The real challenge is link the displayed value to a meaningfull description of the sensor. You could store a list of the the names at programming time and index down them as you printed the readings.

My cheapskate solution would be to display 12 temperatures on the screen and have the names/position of the sensors on a written on a frame around the display.

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Greenbeast
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« Reply #25 on: November 12, 2010, 07:55:55 PM »

You can write/get an arduino sketch that will give you the 1wire sensor address which means to can specify exactly which temperatures you are reading.
I've not bothered, i just display them in the sequence determined by the arduino, then a little juggling round at installation time has given me 5 temp readings that are relative to their position on the tank and you can code that position into the sketch if you need to (i needed to save screen real estate for other information)
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StBarnabas
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« Reply #26 on: November 13, 2010, 10:50:17 PM »

Hi
I have modified Greenbeast's sketch code to display upto 12 readings and Desp has left StBC with an Arduino, a Nuelectronics LCD shield and 1/2 dozen sensors. Hopefully I will be able to integrate Eric's code next week.
I havn't had a chance to look at the libraries in detail but it looks as if sensor 7-12 display a copy of the reading on sensor 6. Code naturally available if anyone is interested (needs to be comment coded up a bit better).



A close up of the display

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Greenbeast
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« Reply #27 on: November 13, 2010, 11:13:17 PM »

Glad you got Desp sorted with something.

I wanted to sort him out earlier in the year but had other things on (also why i've only just picked up my own project again)

One of the problems i was looking to overcome for him was the length of cable usable for the 1wire network.
My network is 2m in length but then i tried using 10m+ cat 5 and it failed.

Is this purely down to the pull up resistor size or the fact i was using parasitic power?


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desperate
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« Reply #28 on: November 13, 2010, 11:16:10 PM »

Hi Sean,
It was a real pleasure to meet you, Mrs StB and your lad, give him a high five from cactusville  genuflect
Thank you again for your hospitality and patience for explaining to me how to set up the monitoring and logging system, also a big thank you to Mr Greenbeast and Mr ericw for your input to this endeavor, it truly will be a miracle on earth to get cactusville electronically monitored.


Desperate
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Greenbeast
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« Reply #29 on: November 13, 2010, 11:17:01 PM »


I havn't had a chance to look at the libraries in detail but it looks as if sensor 7-12 display a copy of the reading on sensor 6.

Yes this does happen all the while you not got a full number of sensors on the network
The sketch addresses the sensors sequentially
Quote
Code naturally available if anyone is interested (needs to be comment coded up a bit better).

yeah, i didn't write it from scratch, just adapted some other sketches/examples and should have notated a little more as i went)
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