Power management questions

Dev Kit Support
1

My use case doesn’t involve the wave data at all, and I’m purely interested in getting the highest possible data granularity from my low power sensors attached via smart mooring. The constraint is obviously that on low sunlight days, the system may run out of power and go to sleep.

So along these lines:

  1. Is there any way to turn off the wave data entirely?
  2. Is it possible to keep my sensor powered on and recording data, and then wake up the buoy to send batched data every now and then?
2

Hi there Chris.

A few questions for you:
a) How much power does your device take up?
b) What would be an ideal sampling scheme for you (10 minutes every hour e.g.).
c) Where will this be installed? Lat can help us determine available solar power.
d) How long do you want the buoy out there?

To answer your questions:
1 – There are some options we can enable to save power by not measuring waves as frequenty or at all. These commands can be set by the CLI locally or by Sofar over satellite. Let’s find out how much power you’ll need first and then we can advise on what to do to get there.
2 – Telemetry messages are triggered by the Bristlmeouth payload. Powering the sensor from the Spotter requires the Smart Mooring to be powered up which does eat up the power. Does your sensor have standalone power/batteries? If so there are other options we can get into.

Z

3

Thanks so much for the info! Some answers:

  1. Likely around 1-2 watts, although this is TBD
  2. We probably don’t want to do a batched on/off system for sampling. Ideally we’d want to just get the tick rate as high as possible and try to avoid data gaps. ie sampling every 30 mins is ok, every minute is better. And samples can be read in <30 seconds from power on.
  3. It’s not clear exactly where it will be installed yet. And in fact there’s a chance it might get installed in shallow water where there’s risk of shadows from land. This is probably out of scope but it’d be great to even have adaptive sampling rates depending on battery state and charging rate.

I would love to hear about commands to turn off the wave sampling! It would just provide more flexibility depending on the solar environment.

We don’t have separate batteries for the sensors. I was just hypothesizing how cool it would be to power the sensor but not the Spotter for this reason. Another way to look at it would be if the Spotter could enter a sleep mode - no waves, no phoning home, etc - and then be awoken by our device.

4

Got it okay. Let me get some help with your original question. Might take a bit to get all the details together.

In the meantime some feedback on what I’ve heard so far:

  • Really interesting questions. What’s the use case? Just curious.
  • I think the latitude and shade/sun placement will be the biggest driver of your highest available sampling rate.
  • Setting a sampling rate based on turning on and off the Smart Mooring can be adjusted from CLI and also in the field from satellite, for satellite you’ll just need to email support@sofarocean.com with what you’d like–super easy.
  • Continuous sampling sort of isn’t our favorite. We have noticed a lot of edge cases and firmware spooky issues whenever we try to do something all the time. We’d recommend for longevity’s sake to include a firmware reset somewhere in your plans.
5

I’m from Aquatic Labs, think we had a videochat once! We’re working on integrating some custom sensors with the buoy and just trying to keep flexibility depending on what deployments/test sites come our way.

For your last point, I’m not sure what you mean by firmware reset. I guess my point is that we wouldn’t want to do like 30 mins on, 2 hours off or something. We’d rather do like 1 minute on, 15 minutes off. I think that’d be blocked by a couple things though, it’s not clear that’s enough time to reliably send messages out.

6

Thanks Chris,

It sounds like we can’t fully disable the wave collection side of things but there are options to extend the power budget. A lot of that is captured here:

Regarding the sampling scheme / Smart Mooring bus configuration, that you can set via the CLI. When you’re ready to try something on that let me know and I can send over some more detailed instructions.

Z

7

Happy to try it now! Yeah I’ve read a bit about dwell, idle, and bridge power manager. Just not sure what the best possible setup would be and how these things interact with bridge power and cellular available.

8

Hi Chris —

Power Save Mode will put the GPS module to sleep when it is not performing wave sampling. Normally, while in RUN mode, the Spotter will perform wave sampling constantly. So, we must make two configuration changes: one to enable dwell, and one to enable Power Save Mode.

Please note: Spotter also determines its physical location using the GPS module. If there comes a need to put the Spotter into TRACK mode during a recovery effort, it is likely that Sofar will have to intervene to change these settings back to something closer to their default.

cfg glpmen 1
cfg dwl 1380
cfg save

The above will enable Power Save Mode, and set the dwell time between wave sampling to 23 hours. Thus, the Spotter will perform wave sampling for 1 hour out of every 24.

Another way to save power is to turn off the visibility LED, or lengthen the portion of its blink pattern when it is OFF.

cfg vle 0
cfg save

Hope that helps.

Thanks,
Tim

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