Computing stuff tied to the physical world

75 days and counting

In AVR, Hardware on Mar 30, 2012 at 00:01

The JeeNode Micro based on the ATtiny84 is getting more and more use around here. One of the ways it can be powered is via a CR2032 coin cell on its back:

I’ve got one with the radioBlip sketch running here, to see how long it will last on a single coin cell.

Well… today it passed the 75-day mark – celebration time!


  1. When will we have the ‘final’ result of this test, in 2, 3, 5 years :-)))?

    Something like a HALT (highly accelerated life test) might be usefull here to get faster results. Not quite easy though, because of the unknown characteristics of the coin cell (internal resistance, self discharge, recovery effects….).

    • I agree that it would be nice to predict a bit better, and not in real time – that needs two things: a reasonably precise “coulombs/day” measurement of the actual JNµ + sketch, and a battery capacity. The latter could be approximated with a somewhat higher drain through a programmable dummy load – both sound like excellent projects to look into one day.

  2. Very nice Result so far !

    Will we be able to order some of these JNµ´s in the near Future ?

    I´d be interested to use it as a Sensornode or maybe even as a Energy Count 3000 Receiver :-)

    • I’ve decided to get some more of the current boards – plans for some revisions are not final enough to create a new design. So i expect them to be available again within two weeks.

  3. Too bad it is sold out. Do you know how many mAh this battery has?

  4. Nice. That means that three AA’s gives at least 1000 days of runtime with this sketch. Do you think adding some simple switchable sensors (no PIR) will decrease the running time a lot?

    (I just put in my first order yesterday, does the JeeMon application already use the EEPROM of the JeeLink?)

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