back to article So cool it 2.4 gigahertz: BATTERY-FREE comms for international band

Embedded wireless solutions company EnOcean is planning to show the first self-powered transmitter to work at 2.4GHz. The radio isn't passive, the power to run the radio is generated through motion, light or temperature changes. Specifically this takes the form of an electromechanical converter which is as easy to press as a …


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  1. Joseph Eoff

    Do NOT

    For example, you could build something where when you press the black button and a little sign lights up saying "Do NOT press this button again".

    If you're going to quote from "The Hitchhikers Guide to the Galaxy," then at least do it correctly.

    1. Anonymous Coward
      Anonymous Coward

      Re: Do NOT

      Yes, the weird black controls (not necessarily buttons) are in Disaster Zone's sundive spaceship, and when you try to operate one of them (that is labelled in black on a black background), a little black light lights up black to let you know you've done it. Not the same thing as the button in the Heart of Gold that asks you to please not press this button again at all.

  2. John Smith 19 Gold badge
    Thumb Up


    IIRC in the mid 90's I saw PopSci articles about fixed light switches with batteries in side (for buildings). The idea was you could alter office layout much more easily as the switches had no wires.

    The article was in an edition on "spread spectrum" applications, which is what this used (all switches on one frequency).

    This sounds better.

    I think self powered is going to be the enabler for these sorts of applications.

  3. Simon Rockman

    I do know the correct quote, the point is that because with this one you don't need a battery you can press the button again and again.

    1. TRT Silver badge

      Yeah, I figured that's what you meant, because that quote is so well known and doesn't work if you get it wrong.

      But I've been making self-powered DNA inspired controls for years. £30 gets you a black button, labelled in black on a black background with a small black light that lights up black to let you know you've pressed it.

  4. Anonymous Custard Silver badge


    For example, you could build something where when you press the black button and a little sign lights up saying "Do press this button again".

    Has someone been partaking of some Douglas Adams lately?

    Entirely understandable if true, if slightly misquoted.

  5. Anonymous Coward
    Black Helicopters


    I remember a guy back in the 80s who said that this very technology is what would be used to enable embedded ID cards, which is what the government(s) ultimately want to implement.

    1. Gordon 10 Silver badge

      Re: Bazza

      Moron. How exactly is this tech any better than an RFID token or something else totally passive for that purpose?

      1. Anonymous Coward
        Anonymous Coward

        Re: Bazza

        Winwns: I'm only telling you what he said, in particular to the means of generating the power required. Typing random Welsh vegetable names seems a little unnecessary, unless you want me to get to know you.

    2. Anonymous Coward
      Anonymous Coward

      Must pay more attention

      > I remember a guy back in the 80s

      I read that as "I remember a guy black in the 80s" and thought: Ok, what colour is he now?

  6. Filippo

    I wonder how much power it takes to refresh an e-ink display.

  7. M7S

    Passive sensors?

    Is this the sort of thing that could enable me to scatter loads of pressure pads around the garden to act as a wireless, self powered net that can alert a home security system when activated?

    Leaving aside the issue of false alarms from the cat, which can be filtered out elsewhere, if so there's a use for these in easy fit and (possibly) maintenance free fire alarms (the temperature bit) and security systems (as well as the pressure pad/door switch, the light sensor could equate to the old electric eye).

    Enlighted replies from those who understand this tech better than me grateful appreciated.

    1. Irongut

      Re: Passive sensors?

      Expecting a visit from James Bond and a squad of marines?

    2. Jason Bloomberg Silver badge

      Re: Passive sensors?

      Yes, that's just the sort of applications these things could be used in. No wires, no batteries, simply drop-n-go.

      However... most security solutions aren't simply passive until activated. They will normally wake-up occasionally and send status signals to prove they are working, haven't been tampered with, and even just to prove they are still there, haven't been stolen! Most importantly to let the system know, as best as can be done, that it will work as expected when required to.

      The last thing anyone wants in a safety or business critical application is something not working when it's needed to work. There is also an issue of guaranteeing delivery; a sensor would normally keep sending an activation in case the receiver does not get it. Not sure how that would work if there's only one activation and no power left for sending a subsequent alert packet.

      I would expect most serious safety or business critical systems to be hard-wired, non-wireless, just to overcome the problems wireless and/or battery powering presents. I can see there might be a use in less critical applications such as self-powered TV-style remote controls and similar

      The biggest issue perhaps is cost and it's questionable whether they are actually any better than the current range of battery powered but long-life sensors and controllers.

  8. Refugee from Windows


    Barcelona or Nuremberg? No choice here, being dispatched by work, so Nuremberg it is. Might even get to see this if I can unshackle myself from our own stand.

    Beer - might be able to get one of those in Germany.

  9. Steve Todd

    I'm struggling to see where

    A low power Bluetooth 4 or nRF24 solution couldn't do this kind of things for years at a time on the power of a single button cell. How is this going to be any better?

    1. Gordon 10 Silver badge

      Re: I'm struggling to see where

      The clue is in the name - embedded. Why embed something with a battery that will eventually die from leakage or need replacing.

      If we take slightly naff example of light switches that another commentard mentioned - its bad enough having to change bulb's let alone batteries in the light switch.

      1. Steve Todd

        Re: I'm struggling to see where

        Unless you're continuously hammering the button then the battery should be good for the life of the button (lithium button cells can last 10 or more years on the shelf before being used). It's not hard to build a circuit that is entirely off until the button press, that powers up, sends a small packet of data like this device and powers down again. You can do that with cheap, off the shelf parts (far less than the €50 dev kit they are talking about - off the top of my head an nRF24 based solution could be built for less than £3).

  10. JP19

    "produces between 120 and 140 microjoules"

    So a 50p coin cell can provide as much energy as 18 million button presses. The button would likely fall to bits before you managed to press it 18 million times and likely costs more than 50p.

    Unless battery changing is really difficult and so expensive these micro power harvesting schemes are pretty much pointless.

    1. Voland's right hand Silver badge

      Re: "produces between 120 and 140 microjoules"

      One more possible application - outdoor systems that need to survive extreme heat or cold. It is not necessary for them to operate at those temperatures, just surviving an arctic winter is often more important. Last time I heard Li cells (all forms of them) were not particularly keen on -40C. Or +60C for extended periods of time for that matter.

  11. Christian Berger Silver badge

    Well they got a patent and licenses to sell

    The technology itself isn't particularly new or innovative. People have been building "signal powered" transmitters for decades now.


  12. DropBear Silver badge


    They were doing this sort of battery-free RF thing for many years now, nothing to see here. The only new bit might be the frequency band (2.4GHz) - they've been using the classic 3/4/8/900MHz bands so far. And yes, I also think the tech is more of a marketing gimmick ("But just imagine! No batteries!") than actual serious advantage over a small long-life battery powered solution, at least in a home automation setting.

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