Author Topic: Combining ListenMode with Noise Wakeup Timer  (Read 2604 times)

joelucid

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Combining ListenMode with Noise Wakeup Timer
« on: February 14, 2016, 05:23:08 AM »
I'm currently waiting for some PCB's to arrive for a TH Mote which I've based on the RFM69CW radio and the CR2032 battery, thus significantly reducing size over the Tino (https://lowpowerlab.com/forum/index.php/topic,1269.0.html). I've also adopted Tom's more attractive round design (https://lowpowerlab.com/forum/index.php/topic,1254.0.html), coming out at a 11mm radius - it looks a lot smaller than both the Tino and Tom's TH Mote.

However the CR2032 gives me only around 1/3rd of the capacity of the CR2450 I had used in the Tino. And I still want to solder the battery on for tightest form factor. Finally I did't want to add a tpl5010 or the am1805 because I want to create many of these and I want my home "manufacturing process" to have a good yield.

In short better battery life than with listen mode alone was needed. I still wanted some of the benefits of listen mode: interactive access to the mote when needed, synchronized collision free updates and no updates unless server active.

Kobuki had an idea some time back (https://lowpowerlab.com/forum/index.php/topic,1325.0.html) which I had previously prototyped but not yet in deployment. It occurred to me that this method could be combined with listen mode (https://lowpowerlab.com/forum/index.php/topic,1136.0.html) to yield a very efficient mode of operation while mostly preserving my requirements:

When the gateway sends the wakeup burst it includes a sleep time in the burst command. Nodes send their update and then sleep for the specified time using Kobuki's method. When they wake from sleep they switch on listen mode again - just in time for the next wakeup burst from the gateway.

As you can see this preserves the synchronized updates. When the gateway is down motes don't try to send anything (although they will fall back to the more expensive regular listen mode during that period). And when I'm about to configure/update my motes I just change the sleep interval to 0 seconds in my crontab to switch to normal listen mode at next wakeup burst.

I measure current consumption of 1.2uA during sleep - which is probably as good as it gets without additional HW. Add maybe 500nA for the actual updates (this could still be optimized) and you end up with around 15mAh per year. Given that the CR2032 has a capacity of 225mAh this satisfies my requirement of multi-year battery life.

Tom has my code so with some luck this will appear (together with the noise robustness changes) in his library at some point.

Joe

WhiteHare

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Re: Combining ListenMode with Noise Wakeup Timer
« Reply #1 on: February 14, 2016, 03:43:23 PM »
What about the "lifetime" mote you had referred to that won't ever require new batteries?   Is that a different thing, or will this be the platform for that as well?

joelucid

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Re: Combining ListenMode with Noise Wakeup Timer
« Reply #2 on: February 14, 2016, 04:19:17 PM »
Quote
What about the "lifetime" mote you had referred to that won't ever require new batteries?   Is that a different thing, or will this be the platform for that as well?

Oh no, I hope my lifetime will be much longer than a decade ;-)

WhiteHare

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Re: Combining ListenMode with Noise Wakeup Timer
« Reply #3 on: February 14, 2016, 04:38:15 PM »
If you ever change your mind, it might be worth mentioning that I was able to solder some  tpl5010's without too much trouble, even though I've had almost no prior experience with soldering surface mount.  There's plenty of space between the pins. 

I can't yet comment on the am1805's, as I'm still waiting for the adapter boards to arrive.

I once found a vendor who would solder parts for free (using a microscope) if you purchased your parts from him.  I think there may be other prototype oriented places that may do similar.  Anyhow, I'm tempted to revisit the idea, because in general I'd rather not be the one doing it.

« Last Edit: February 14, 2016, 05:06:19 PM by WhiteHare »

joelucid

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Re: Combining ListenMode with Noise Wakeup Timer
« Reply #4 on: February 14, 2016, 05:21:17 PM »
That's good to hear. I'm waiting for other PCBs that do include the am1805 and other logic to enable really long battery life. The TH mote project was really just a quick side project to be as simple and small as possible. It's just the 328p, the rfm69cw, the si7021 and a single cap. The boot loader also helps: not a single connector.

joelucid

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Re: Combining ListenMode with Noise Wakeup Timer
« Reply #5 on: February 23, 2016, 04:19:18 PM »
Here are a couple of pics of the mote I developed this mode for. Tiny, makes Tino look like a dinosaur really, 10 years battery life and super easy to solder. No short, worked immediately.

As the pic with the radio shows this is as small as you can get using rfhope's modules.






Joe

TomWS

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Re: Combining ListenMode with Noise Wakeup Timer
« Reply #6 on: February 23, 2016, 05:45:27 PM »
makes Tino look like a dinosaur really,
I've always thought that Tino looked like a dinosaur.  Glad you've finally come to that realization!   ;)
Quote
10 years battery life and super easy to solder. No short, worked immediately.

As the pic with the radio shows this is as small as you can get using rfhope's modules.

Congratulations!  Good job!

One question, however, why did you compare with an American Quarter and not a Euro?

Tom

TomWS

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Re: Combining ListenMode with Noise Wakeup Timer
« Reply #7 on: February 23, 2016, 05:52:26 PM »
I think this deserves a nice wooden enclosure, Joe.

Tom

joelucid

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Re: Combining ListenMode with Noise Wakeup Timer
« Reply #8 on: February 23, 2016, 06:00:34 PM »
Yeah if I had the tools :-)

But I think it looks pretty cool naked also:



I might need to stop by my 3D printing cafe again. Picked up the sprinkler lid today - it turned out great.