Computing stuff tied to the physical world

The beat goes on

In Hardware on Sep 4, 2011 at 00:01

Today, a milestone was reached:

    $ jeemon examples/driver-demo/
    15:45:01.975 RF12demo config usb-A700fdxv RF12-868.5
    reading:RF12-868.5.3:radioBlip:ping = 493295
    reading:RF12-868.5.3:radioBlip:age = 365

That’s nearly half a million packets, one every 64 seconds, all on a single LiPo battery charge:

Screen Shot 2011 09 03 at 15 51 53

The setup is very simple. A 1300 mAh LiPo battery (I just picked one up in a camera shop with a convenient size), attached to a JeeNode USB:

At 3.94 V the battery is still far from dead, so it’ll probably stay alive for quite a bit longer…

The sketch running on this node is:

Screen Shot 2011 09 03 at 16 14 28

(looks like I had lost the low-power stuff in the “radioBlip” code, now fixed on GitHub)

Lots of low-power nodes are holding out nicely here at JeeLabs, by the way. There are about half a dozen permanent room nodes, and with the latest roomNode sketch they just keep going. Some are running on 3x AA rechargeable EneLoop batteries, others use 3x AAA with even less juice, and all of them have been running with just a single charge since the beginning of this year.

  1. I love you, everlasting jeenode.

  2. Jc,

    are you sure u did not accidentaly charged the battery a bit when hooking it up to the computer?

    Here i’ve got a roomnode (with PIR, LDR and SHT15, 3xAA) running since june 30th. Nothing fancy, but this one has been transmitting his status every second from the start. Still going strong.

  3. Hi JC, I’m surprised of your lifetime LiPo… I’m running the same code + SHT11 measures added in the payload buffer. Payload is sent every 5 minutes. My 3.7V (3400mAh !!) went empty after 3 months. I’m using a stepup converter (MAX1724)to keep supply voltage when LiPo is under 3.3V (2.8V is the limit because LiPo automaticaly shutdown at 2.8V because of undervoltage protection -> internal protection circuit).

    One difference, i’m doing this before going in “sleep mode” :

    rf12_sendWait(1); -> Idle (instead of PWR_DOWN in your code) rf12_sleep(0);

    Can it changes everything?

  4. apart from CPU shutdown modes, you may have a high idle current from that step-up converter. How does that circuit work anyway, do you bypass the stepup until the battery voltage drops beneath 3.3 V? Is the stepup output set to 3.3V? (in which case it must be a buck-boost or SEPIC type converter, if it’s working while battery voltage > 3.3 V) ?

    By the way, I compared two step-up converters recently: their idle currents were 200 uA, and 1.2 mA (!) See also:

  5. Hi JC – a question I’ve been meaning to ask for ages and just got round to, which is that whenever you photograph Jeenodes you seem to show the antenna streched back along the circuit board rather than pointing out into the air – I’m guessing this is to get it in the photo and that you don’t run nodes this way?

    (Its been niggling me for ages!)

    • Nah, I usually run them that way as well – works fine for me. If range is an issue, it would indeed be better to point them outwards, perpendicular to the board as ground plane. And to orient all of them in the same way, i.e. vertically.

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