Jonathan Pickett

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9 years, 2 months ago.

deep sleep power consumption excessive

mDot.h @ line 650 says deep sleep is available. Looking at the developer manual for the mDot(http://www.multitech.com/manuals/s000612_3.pdf) on page 19, I am expecting deep sleep to consume 30-33uA. When I measure the current draw I am seeing about 7.5ma. It doesn't seem to make any difference what I specify for the wakeup_mode or deepsleep parameters. At 7.5ma my batteries will last a week. I am hoping for better than a year. Is deep sleep really supported in libmDot?

I am testing with a bare device using the mDot sleep example (https://developer.mbed.org/teams/MultiTech/code/libmDot_sleep/)

Question relating to:

Last updated: 18 Nov 2016
Library for LoRa communication using MultiTech MDOT. Lora, mdot, multitech

3 Answers

Mike Fiore
9 years, 2 months ago.

Hi Jonathan, Can you give us more information about your setup? The following would be useful:

  • mDot library version
  • are you using a UDK2?
  • is anything else connected to the UDK/mDot that could be drawing power?
  • relevant source code
  • anything else you think we should know about your setup

You might have an old version of the mDot HW which didn't support the uA range current draw. There should be a string of characters silkscreened somewhere on the mDot PCB. Can you provide that, as well as any information on the sticker that should be on the mDot?

Thanks, Mike

Accepted Answer

libmDot is at the latest version (revision 8:57978a837b2d). I am using the UDK2, but my test is with the naked mDot. I have nothing connected to it other than power, antenna and multimeter. The code running on the mDot is https://developer.mbed.org/teams/MultiTech/code/libmDot_sleep/ with line 85 modified as follows dot->sleep(600, mDot::RTC_ALARM, true);

Silk screened on my mDots is: 94V-0 (above the can to the right) In the copper layer, above the silk screened text is: 10000701LA

I have two mDots on my desk. From the sticker: DOM mDot #1 : 2015 07 30 Serial# mDot1: 18300162

DOM mDot #2: 2015 06 23 Serial# mDot #2: 18239529

posted by Jonathan Pickett 08 Sep 2015

Jonathan, I believe you have the older revision of the mDot which doesn't support the uA range current draw during sleep. Please open a ticket on our support portal so we can see what the next steps are.

https://support.multitech.com/

Cheers,

Mike

posted by Mike Fiore 09 Sep 2015

Interesting Mike. I knew the version of the mDot I was buying were engineering samples as they hadn't got the final low power version finalised at the time. Is it a firmware upgrade or a complete hardware upgrade for the low power to work properly? Not a problem as the existing mDots are fine for my development and research purposes and can wait until the full production versions are available generally.

thanks

Andrew

posted by Andrew Lindsay 10 Sep 2015

Andrew,

We actually did a board spin and made some HW changes, unfortunately. I'm glad it's not a showstopping issue for you!

In case you're interested, the US version of the mDot has been officially released, and the EU version will be releasing very soon!

Cheers,

Mike

posted by Mike Fiore 10 Sep 2015

Mike, Could you be more transparent on this issue ? I've came across pieces of information regarding deep sleep on mDot scattered all over the place but in the datasheet. By more transparent I mean, could you reveal what was the reason to drop this feature for this revision. Maybe there is a hardware workaroud. I've bought dev kit with gateway and all the bits recently (Jun 2018) and the mDot bundled is still apparently incapable (94V-0 ?) of deep sleep. I'm designing a product and I need deep sleep; how can I guarantee sourcing new revision ? -Mateusz

posted by Mateusz Grzywacz 02 Aug 2018
Erik -
9 years, 2 months ago.

I don't have the MDOT, but in general the rest of the board can have significant power consumption. Do you have seperate code to disable the wireless part? And check which other stuff is on the board. Looking at the input voltage range, I assume there is an LDO on board. How much quiescent current has this LDO?

Andrew Lindsay
9 years, 2 months ago.

Hi,

I've tried the deep sleep but have yet to measure the actual current drawn while sleeping. Depending on what else is connected to the mDot you may get slightly higher readings than those specified in the developer manual. If you have sensors and devices that do not have a sleep or low power mode then you'd need to add in FET control to turn them off during sleeping and back on when the mDot wakes.

Hope this helps

Andrew