Computing stuff tied to the physical world

The beat still goes on

In Hardware on Jan 19, 2012 at 00:01

Recently, the radioBlip sketch reached yet another milestone: it’s been running for 500 days on one LiPo charge!

Screen Shot 2012 01 16 at 22 48 01

Seems like a good time to start a new duration test, this time with a JeeNode Micro:

DSC 2857

Since I don’t want to have to wait yet another 500 days, I decided to up the ante:

DSC 2858

The JeeNode Micro includes holes for a CR2032 3V battery holder, so why not try that for a change, eh?

The sketch was modified slightly, to set the proper clock divider on startup:

Screen Shot 2012 01 16 at 19 37 00

I’ve set it up as node 18, and it’s been blipping happily:

Screen Shot 2012 01 16 at 19 34 27

Let’s see how many days that little JNµ can dance the Sputnik shuffle…

  1. LOL… I have a JN USB here that can do about a week on a 1300mAh LiPo… Then again it needs to be able to receive all the time, so the RFM12B is always powered up.

    500 days is just silly!

    Very impressed that the JNµ is working, I thought the peak supply current of the coin cells wouldn’t be enough to power an RFM12B, and I don’t see any big reservoir capacitor to help it along. Looks like it’s perfectly suited to a keyfob design… Just have to find a use for it!

    • I am using the CR2032 in different designs (MSP430 and ATmega324) where the peak supply during data read out is also in the region of 30-40mA and I never had problems with it. They run for ~5-10 years just maintaining time and date and even after 5 years they are capable of delivering this ~40mA with more than 2.2V (and there is an additional voltage drop from a schottky diode).

      Maybe the internal resistance of the cells also depends on manufacturer, mine were Varta.

      A keyfob (MSPnode hardware, but AVR should be comparable) works perfectly with the CR2032 (no big C used, just the ‘normal’ decoupling caps).

  2. Could alternate payloads equal Vcc please? The death spiral of the coin cell is useful design info for setting an early warning alarm threshold.

    “Buddy, can you spare a few μC ?”

    • You mean add an ADC readout to the sent data? Yes, that could be done – I admit I was a bit lazy on this one…

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