Author Topic: Three Component Data Logger (that works with Moteinos!)  (Read 2014 times)

EdM

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Re: Three Component Data Logger (that works with Moteinos!)
« Reply #15 on: February 13, 2017, 04:17:42 PM »
Thanks!

While I was looking at those, I also spotted this on the vishay site:
http://www.vishay.com/docs/73338/si1499dh.pdf

which quotes Rds down to -1.2v, (although I don't want to solder an SOT-363 adapter by hand). I have not investigated low voltage stuff yet (as the SD card kind of pins me to 3.3v), but it looks like there are mcu controllable Fet options all the way down to the brown out of the 328P.

P.S. What really caught my eye on your site was the TPL5110 Breakout. That looks like an extremely handy board...

ChemE

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Re: Three Component Data Logger (that works with Moteinos!)
« Reply #16 on: February 13, 2017, 05:21:41 PM »
P.S. What really caught my eye on your site was the TPL5110 Breakout. That looks like an extremely handy board...

Yeah, that little gem lets you shave the last 4.4uA down to 35nA plus sensor sleep currents.  A Mote with depowered sensors (I ruthlessly cut the power to everything and it works fine for me) would sleep on 285nA assuming you bypasses the LDO and were running straight on batteries.  How long would your cave pearls last with that kind of sleep current?

EDIT: I swear English is my first language...
« Last Edit: February 13, 2017, 05:52:12 PM by ChemE »

EdM

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Re: Three Component Data Logger (that works with Moteinos!)
« Reply #17 on: February 13, 2017, 05:38:28 PM »
"How long would your cave pearls last with that kind of sleep current?"

....Far longer than my wife has the patience to wait for the data :-) 

But seriously, those kind of sleep current open up other interesting possibilities like cold climate deployments. Even lithium batteries don't like operating in February, in northern Canada.  And then there are sensor warmups. Some CO2 & other gas sensors have significant draw during the periods before they will read, so I am sure I will find other uses for whatever power I can save on the sleeping time.


 

ChemE

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Re: Three Component Data Logger (that works with Moteinos!)
« Reply #18 on: February 20, 2017, 12:12:17 AM »
Getting back to the subject of lower power data logging, I picked up a FRAM chip from Mouser to fool around with and since I've never soldered an SOIC-8 package, I figured it would stretch me a little.  Turns out SparkFun's SOIC-8 BoB makes it really easy, the vias in the middle of each pad are a good idea to me.  So this little chip is impressive from a low power standpoint.  At idle it draws 1.2uA.  During writes it draws around 3mA so it can easily be powered from a GPIO which lets you turn it off when not needed.  It takes 1ms from power up to be able to write data and I am able to read and write at speeds of 2.42us per byte (3.3Mbps).  Since FRAM writes at bus speeds, you can depower it as soon as you finish writing to the SPI bus.  Not sure how much data you log, but FRAM is certainly very interesting.
« Last Edit: February 20, 2017, 12:21:36 AM by ChemE »

EdM

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Re: Three Component Data Logger (that works with Moteinos!)
« Reply #19 on: February 21, 2017, 06:54:39 PM »
It's on the to-do list for when I wrangle the code into something more generic, using struct's to store the variables properly instead of the clunky pstring/ascii method I'm using now.  I can already see the day when I drop SD cards from the system, and opt for some kind of optocoupler system to retrieve data from the loggers. Fram will clearly be the way to go there, and by then I will probably have other people's code examples to follow...

For now though we are well past the one year benchmark even with pokey I2C eeproms, so I spend most of my time adding new sensors to what we've already got...