Author Topic: Tiny TH Mote  (Read 10877 times)

TomWS

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Tiny TH Mote
« on: August 25, 2015, 04:47:16 PM »
Well, after all the work that joelucid has done perfecting ListenMode and convincing me that we could, in fact, run for a significant amount of time using CR2032 batteries (see thread https://lowpowerlab.com/forum/index.php/topic,1136.0.html), I've finally got my Tiny TH Mote operational.  This runs from a single CR2032 battery with an overall diameter of just 26 mm.  The device is layered with ATMega328P and Si7021 TH monitor on one side, the RFM69W radio on the reverse side, and then, stacked behind the radio, is the CR2032 battery, for an overall thickness of slightly less than 13mm.

I'll be posting the design files, some code, referencing the new RFM69_ATC library, and showing how I intend to package this cute little thing.  I'll also track battery life data here.  Meanwhile, just to show that it exists, here are a couple of photos...  The second one is the pogo pin board I use to do initial program load into the device.

Enjoy!

Tom
UPDATED: 9/11/15 Added Eagle Design Files.  The only change from the original files is that I increased the size of the pogo-pin holes to accept the pins themselves and make a larger target for the probe.

« Last Edit: September 11, 2015, 05:07:32 PM by TomWS »

joelucid

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Re: Tiny TH Mote
« Reply #1 on: August 25, 2015, 06:49:09 PM »
Looks great! Can't wait for my boards to arrive. I need to send you a copy of the bootloader so you don't need to mess with pogo pins ;)

TomWS

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Re: Tiny TH Mote
« Reply #2 on: August 25, 2015, 08:58:48 PM »
Looks great! Can't wait for my boards to arrive. I need to send you a copy of the bootloader so you don't need to mess with pogo pins ;)
Yes you do!  Been waiting for that...

T

Felix

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Re: Tiny TH Mote
« Reply #3 on: August 25, 2015, 09:43:05 PM »
Nice, if you guys use W then you could just use CW radios which have the RFM12b pinout, and it's 16x16mm instead of 16x19mm.
But I don't carry those :P

TomWS

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Re: Tiny TH Mote
« Reply #4 on: August 25, 2015, 10:08:22 PM »
Nice, if you guys use W then you could just use CW radios which have the RFM12b pinout, and it's 16x16mm instead of 16x19mm.
But I don't carry those :P
Good point!  I hadn't thought of that!  Too bad CR's don't come in 16s...  (UPDATE 2015-08-26 18:13:00: removed goofy comment WRT this being a bad suggestion)

Tom
« Last Edit: August 26, 2015, 06:13:51 PM by TomWS »

gregcope

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Re: Tiny TH Mote
« Reply #5 on: August 26, 2015, 02:57:35 AM »
Lovely little beauty...

joelucid

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Re: Tiny TH Mote
« Reply #6 on: August 26, 2015, 12:57:24 PM »
According to the data sheet it does have listen mode. Isn't this just the same module in another form factor? This could definitely shave off a few millimeters if we use cr2032 with pins and no battery holders.

TomWS

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Re: Tiny TH Mote
« Reply #7 on: August 26, 2015, 06:11:16 PM »
According to the data sheet it does have listen mode. Isn't this just the same module in another form factor? This could definitely shave off a few millimeters if we use cr2032 with pins and no battery holders.
Boy, I don't know what I was looking at when I made the comment (maybe RFM12 datasheet?) but I totally messed up on this one.  My apologies to Felix, yes, this is a good suggestion.  I'm going back to modify my previous post.

Tom

luisr320

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Re: Tiny TH Mote
« Reply #8 on: August 27, 2015, 05:37:48 AM »
Just shut up and take my money!  :)
Where and when will these be available?
If they came with a wireless loading sketch in them, it would be a turnkey solution: get them out of the box, connect the battery, load your new sketch wirelessly and you are all set up and ready to use them.
And how about inserting some kind of probes or prongs and make them soil moister sensors? That would be also very neat.

joelucid

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Re: Tiny TH Mote
« Reply #9 on: August 27, 2015, 07:08:49 AM »
Quote
And how about inserting some kind of probes or prongs and make them soil moister sensors? That would be also very neat.

Luisr, that's exactly why my design (2.5cm square) while not quite as elegant as Tom's has 18 connectors on the side to enable custom projects. And yes, the preinstalled wireless bootloader really helps since you don't need to connect any wires to program it. Either put a CR2540 coin cell on top for 540mAh of capacity (that's about the same as a 9V battery!!!), or use it with 2x aaa or aa lithium if you need even more power for sensors.

TomWS

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Re: Tiny TH Mote
« Reply #10 on: August 27, 2015, 08:59:21 AM »
Either put a CR2540 coin cell on top for 540mAh of capacity (that's about the same as a 9V battery!!!)
Except that, with the CR2540, you get to USE almost all of the 540mAH.  You only get to use 1/3 of the 9V battery's...

Tom

joelucid

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Re: Tiny TH Mote
« Reply #11 on: August 27, 2015, 10:11:03 AM »
Quote
Except that, with the CR2540, you get to USE almost all of the 540mAH.  You only get to use 1/3 of the 9V battery's...

Actually you do get all of the mAh out of the 9V battery - but 2/3rds of the energy heats the room via the voltage regulator. In addition to the higher energy density of lithium batteries that's the reason why the CR2540 can be so much smaller while providing the same battery life.

TomWS

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Re: Tiny TH Mote
« Reply #12 on: August 27, 2015, 10:23:10 AM »
but 2/3rds of the energy heats the room via the voltage regulator.
I suppose, where you live, heating the room is useful   ;D
I should add that that's probably true for Felix as well...
T

luisr320

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Re: Tiny TH Mote
« Reply #13 on: August 27, 2015, 10:30:16 AM »
Quote
And how about inserting some kind of probes or prongs and make them soil moister sensors? That would be also very neat.

Luisr, that's exactly why my design (2.5cm square) while not quite as elegant as Tom's has 18 connectors on the side to enable custom projects. And yes, the preinstalled wireless bootloader really helps since you don't need to connect any wires to program it. Either put a CR2540 coin cell on top for 540mAh of capacity (that's about the same as a 9V battery!!!), or use it with 2x aaa or aa lithium if you need even more power for sensors.

Looks like an opportunity to join efforts and create something Greater than the parts  :). And Felix already have a neat store to sell them. I would buy a lot of them.

Felix

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Re: Tiny TH Mote
« Reply #14 on: August 27, 2015, 11:12:26 AM »
Interesting to say the least :)
I would propose going to the 5x5mm 32-MLF or 4x4mm 28-MLF package. That would leave room for other things or perhaps add FLASH memory for wireless programming :)
I would be curious how well a CR battery can handle the burst transmission required by wireless programming though :P
Probably not extremely well, but transmit power could be decreased and hence shorten range of WP to help the battery. The gain is wireless programming when these sit on top of your house, so maybe worth the effort.