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Author Topic: Open Source Data Logger Project Using the Arduino?  (Read 34831 times)
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I would think everything but a timer would be powered down between readings if battery drain is a critical factor. Perhaps WHEB could say at what frequency he would like to log readings.
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Hi kg4wsv,

Thanks for the reply. According to the manufacturer's specs (USGlobalsat Inc.) power consumption of the GPS engine board (model EM-406a SiRF III) used in the Sparkfun GPS logger is 44mA. However, Sparkfun list it as 70mA (?). Sparkfun list the total power consumption on the GPS datalogger as 160mA, so I figured that the bulk of the difference was due to logger itself (I could be way off however).

You raise a really interesting idea with the notion of limiting the sentence output. We've discussed the idea here but our utter lack of electronics/programming knowledge meant it was a bit of a pipe dream. Many of the sentences are of little use to us and we really only need date, time, lat/long and HDOP values (possibly satellite number as well to help determine fix quality). Almost all of our projects require reasonably long deployment periods (from two weeks to many months), so fix logging intervals are usually set to between five minutes and one hour, with the unit being in sleep mode the rest of the time. Intermittent operation obviously boosts battery life/deployment (although we're finding some interesting results in terms of the benefits of longer intervals - - i.e. there doesn't seem to be many), but do you think reducing sentence output would have much of a positive impact? Would certainly make things easier when transferring data over at the end of deployment, regardless.

I am wondering how difficult it would be to interface the same GPS engine board above with an Arduino board to play around with sentence output etc? I realise this is all a bit ambitious for a newbie, but I am happy to jump in and try, particularly if there are other people interested.

Cheers
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Hi Mem,

I probably covered fix rates a bit in my last post, but to clarify, we're definitely keen on hourly (or less) fixes. Our static tests are revealing some intriguing battery life projections for five minute fixes, which seem to be the best of both worlds in terms of accuracy (very good average DOP values & Sat #) and operational time (~8secs - 10secs to get a fix with a hold-off value of five). We've run the logger for 7 days at a five minute fix rate using two Duracell DL123 batteries in series (~1550mA capacity) and voltage only dropped from 6.4v to 5.89v. The SF GPS logger tolerates voltages between 4v and 7v, so we were very pleased with these preliminary results, as we might get a couple of weeks of deployment at least out of this set-up. Sleep draw of the SF logger really seems to be the major limiting factor (1.5mA) in deployment projections.

Cheers
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WHEB,

Does the thing you're measuring ever stop moving???  If so, you can wire things up to power down with no movement.  Your last GPS reading would be the location that the thing stopped.  If there is constant motion, then this wouldnt help.  I just did something similar and it seems to be working great so far.  
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If you're talking about report intervals to something on the order of tens of minutes to hours with the GPS asleep between events, reducing GPS sentences won't help enough to be noticeable.  When I mentioned it, I was thinking of a continuous (e.g. a report on the order of once a minute).

I would check out the GPS start time.  Especially with 5 minute intervals, you may be running the GPS a majority of the time, as 5 minutes to first fix from a cold start is not unreasonable to expect.

I like the 123As for physical size, but the Energizer AA lithiums actually have more capacity, if you can stand the four AA form factor to get 6V (compared to the two 123As).

-j

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I am a biologist from a wildlife research group in Australia.
There are a number of Australians that hang out here, you might want to be more specific about where you're based--you might be living next door to one. (Although I don't think Aussie Arduino users are required to be registered yet... smiley-grin )

On the subject of battery life, you might want to look at:

  http://www.faludi.com/projects/arduino-and-xbee-battery-test-results/

Keep in mind that if your processing needs are low you have the option of using lower-power and/or frequency parts.

--Phil.
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WHEB,
I gave it some more thought and if your project can withstand an hour or even a half hour between gps pings, then powering down might not be a bad option, even if there is constant motion.  Also,  you might want to check out batterys like http://www.megabatteries.com/item_details2.asp?id=14282&cat_id=404&uid=1638.  You can regulate the voltage and get a lot more mAh out of them.  Food for thought.
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Hi everyone,

I have to say this is a great forum and thanks for all the responses. I've found little interest in some other non-Arduino forums. I'll try to reply to each point separately.

fornsix
We're tracking dingoes and wild dogs, which are always on the move just about. I guess it would depend on how sensitive the movement "switch" was in terms of extending battery life. For example, if it switches on with head movements, it might never get a rest. If it can be tailored to trigger upon a certain degree of movement, it may well result in some savings. Thoughts?

kg4wsv
I should have qualified my earlier point that the SF logger actually already allows NMEA sentences to be partially restricted to pretty much only those sentences that you want. As far as we can tell, it's not possible to only store parts of sentences though (i.e. it's either a whole sentence or nothing). There are also some issues with the way the data is stored when it comes to importing into something like a spreadsheet app., but this is more of a pain then a major problem. It would be great if we could chop and change individual sentences to get exactly what we want without a lot of messing around, but it is probably easier to do this at the end of a given deployment using existing GPS applications rather than trying to program the board to do it in the field. You're right that the Energizer AAs have more capacity than the 123s, but weight is a bit of an issue for some of our projects. The case we're using in an upcoming project is too small to fit AAs, or even three/four AAAs, but the stocky nature of the 123s, coupled with the fact that we only need two, means we can "cheat" a little and embed the batteries on the side of the case using epoxy and still keep the weight down. The case has to be top-mounted to the collar because the SF loggers have an integrated antenna. Even if they didn't though, I actually like the top-mount, because trying to fit/adjust collars in the field and dealing with a length of coax (or something similar) leading to an antenna is a nightmare. To stop the collar from spinning around, we mount a collar drop-off device and a few other components near the bottom side, which all adds to a little more weight than the GPS case.

We might still end up using AAs for medium term deployments however.

follower
We are based in Brisbane so it would be great if there were a few Arduino aficionados nearby who might be interested in helping. Thanks heaps for those battery life test results as well. Like the SF GPS datalogger I imagine getting the most out of sleep modes could have a lot of impact in terms of battery life.

fornsix
Thanks for the link. We've looked at using similar batteries for long-term deployments, and we still hope to, but there have been some issues relating to the max. current rating of these large capacity D- and C-cells. We were hoping (read pushing our luck) that a single cell would cut it, but the voltage drop/draw when the GPS was operational ended that idea. Using two cells in series seems to work, but we're yet to do proper bench tests to ensure they're going to last in the field. We're just using a diode to drop the voltage of the pack, which seems to work ok.

Cheers everyone, much appreciated.

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We are based in Brisbane so it would be great if there were a few Arduino aficionados nearby who might be interested in helping.
Hi
I am your local Arduino expert. smiley-wink
AFAIK I'm the only one in Brisbane.

You can use a single cell and boost it to 5v fairly easily.
Maxim has a chip which does this which I'm currently using in a project.
It gives a stable 3.3v or 5v from as little as 0.8v.
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Hi Cheater,

I can't believe you're in Brisbane! Small world huh?

The voltage booster sounds like an interesting idea. Would there still be a potential problem with the max. current of the large capacity lithium batteries, as they're only rated to 200mA continuous (some only 100mA) and 400mA pulse? Given that the GPS logger is supposedly using 160mA when active, I guess it shouldn't be a problem for 200mA+ batteries. Would the Maxim chips be much of drain on batteries? We've also been messing around with some mini solar panels (http://www.powerfilmsolar.com/products/oem_components/modspecs/sp337.htm) in the hope of trickle charging collar batteries and these chips might be perfect for boosting voltage.

Another question I have in relation to GPS and the Arduino boards is whether it might be possible to set up something to trigger a small wireless camera on a collar when a collared animal gets close to waypoints? We tested a prototype wireless camera collar last year with great success, and since then I've been looking to develop the camera collar idea further. I've been interested in GPS controlled devices on-board collars for ages, but my lack of electronics knowledge has left me day dreaming about such ideas.

I am due for some fieldwork within the next couple of weeks, which will see me away for about six weeks, but if you were keen, it'd be great to follow up on some of these ideas upon my return.

Cheers
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I can't believe you're in Brisbane! Small world huh?
Its a very small world. smiley

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Would the Maxim chips be much of drain on batteries? We've also been messing around with some mini solar panels (http://www.powerfilmsolar.com/products/oem_components/modspecs/sp337.htm) in the hope of trickle charging collar batteries and these chips might be perfect for boosting voltage.
The Maxim chip doesnt use much power but you do want to be careful.
It boosts the voltage by drawing more amps. They are over 90% efficent but I'd still be looking at using two of those batteries in parallel.

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Another question I have in relation to GPS and the Arduino boards is whether it might be possible to set up something to trigger a small wireless camera on a collar when a collared animal gets close to waypoints? We tested a prototype wireless camera collar last year with great success, and since then I've been looking to develop the camera collar idea further. I've been interested in GPS controlled devices on-board collars for ages, but my lack of electronics knowledge has left me day dreaming about such ideas.
Thats pretty straight forward. Its just a matter of comparing the current position to a list of waypoints.

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I am due for some fieldwork within the next couple of weeks, which will see me away for about six weeks, but if you were keen, it'd be great to follow up on some of these ideas upon my return.
Sure. smiley
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In this thread http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1199737337/15#15

one of the arduino members is storing GPS data to an SD card using arduino. It might be helpful to ask him about his project and how its going.
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I have been following this thread and was delighted when I read about this the other day:

http://www.ladyada.net/make/gpsshield/

Will order one of these soon. Has anyone made anything interesting with it yet? I'd be interested to know how many i/o pins it uses and if there's enough 'code space' to add 1wire temperature stuff or other sensors. One idea I had was to use it for geo-tagging. If I simply added a push-button that would timestamp co-ordinates on the SD card I could just link them to the photos.

Regards,

Till


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More ladyada -
she does some analysis of the uses of MAX756 as a voltage booster as part of the design of her MintyBoost. The whole page is quite fascinating from a 'following the thought processes in getting from problem to solution' point of view.

http://www.ladyada.net/make/mintyboost/process.html

You're in Brisbane?! smiley
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Cheers,

PeterV in Canberra

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The DateTime library in the playground keeps time with no additional parts.  I am using Adafruit's resonator based USB boarduino with no time accuracy issues.

A hardware real-time clock to handle power loss would be required if not using batteries.

The new alarm library has the potential to simplify programming of a data acquistion system.

The ethernet library in release 012 would allow long cable lengths 100 meters and web based communication.

In summary, the Arduino platform has lots of potential in this area.
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