sensor type: "presence sensor", but not PIR

  • I'm one of those waiting for the Raspberry Pi gateway. Very excited and grateful for the work going into this.

    In the mean time, I got this idea from the smartthings site. Am I right that sensor types have to be pre-defined so that the gateway knows that to expect from the sensor node? If so , I would like to have a sensor type call "presence sensor". It'll be an Arduino running on batteries that sends a periodic signal to the gateway via nRF24L01. If the ping stops comming, it means Arduino is too far away from the gateway. Could be used to alert you when the dog has run out of the yard, for example.

  • rather cool idea. Could also be used for things such as vehicles. Pull in to driveway, and thus in range, and poof, script something to happen. 🙂

  • Great idea!

    As of detecting presence - currently I'm using openwrt router to see if phones are in home (wireless network), which also shows who's exactly around house.
    Could be RFID also, i.e. near keys.

    But the example you gave with the dog... Nice. 🙂

  • Mod

    Checking for presence of my phones does not work because my router does not refresh it's table of connected devices very well (Fritzbox).

    I have read about the suggested solution of having a nRF24L01 device appear/disappear somewhere as well.
    In this example it was installed in a car to open up the garage door as soon as it is in range 🙂

  • Hero Member

    do you think the nrf24l01 would be reliable enough? i think you would get enough false alarms to get annoyed with this.
    still worth exploring and testing...perhaps the idea could be extended to use a 433mhz transmitter in addition to the nrf24 so if both disappear then the dog has finished digging under the fence and visiting your neighbourhood!

  • brilliant idea, lets go high tech and make it use the repeater nodes to detect where by triangulation too
    could mix this with GPS and google maps

  • I would think you could do this by setting up a sensor as a switch. Another one would be set up to communicate with the first instead of sending to the gateway. The first one is made to set itself as "off"(no presence) on the gateway if it hasn't received a ping from the actual presence sensor in the past, say, 5 seconds. When it does see a ping, switch set to on.

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