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I know it's not [officially] supported, but has anyone tried to use a splitter to try two sensors.

Miguel BuenrostroMiguel Buenrostro
edited December 2012 in Miscellaneous Vote Up1Vote Down
Anyone hook up a splitter and try using two of the same [or different] sensors?

Each sensor has a uniqueId, if I understand correctly, so I wonder if a splitter would allow two sensors to work. I could see a problem with the same sensorType (two magnetic, for example since maybe the interface supports only one), but maybe, just maybe, two different sensor types might work?

I'm just wondering and trying to get the most out of this nifty thing.

Best Answers

  • 8 Comments sorted by Votes Date Added
  • Bill SpencerBill Spencer
    Answer ✓ Vote Up2Vote Down
    Since the breakout board has only one set of contacts, you would have to wire the external switches (magnetic or otherwise) in some configuration that ends in two wires. Say you have 3 magnetic switches wired in parallel with each other and connected to the Gnd & IN connectors on the breakout board. Then if any one of the switches closed twine would say the sensor was closed. There's no way to tell which one in this example.

    If you wired the 3 switches in series, twine would see the sensor as open unless all 3 switches were closed. If any switch was open the sensor would show open but you wouldn't know which switche(s). (A possible way to wire door & window security switches)
  • Bill SpencerBill Spencer
    Answer ✓ Vote Up1Vote Down
    Yes, it would work, but it is a bit more than you need for this purpose. The voltage specification refers to the maximum voltage you can apply to it, and since the twine only provides 3.3v it won't be a problem.

    But if you look at http://www.radioshack.com/product/index.jsp?productId=12706328 you will see a simpler and cheaper magnetic switch that will work perfectly with the twine sensor. When the magnet is near the switch it will close, and when it moves away the switch will open. You don't need to worry about the voltage specification. Radio Shack has other similar switches depending on how you need to mount them, and you can also find these at places like Home Depot, Lowes, Menards or some hardware stores where they sell security products.

Answers

  • Gerry MuellerGerry Mueller
    Vote Up1Vote Down
    Actually, I think there would be more of an issue with two different sensor types, depending on how sensor type is encoded. With two or more of the same, the Twine would likely see them as only one, and would trigger when any of them triggers. You wouldn't know which one, only that one had. This might work well with the mag switch checking for open doors. You can do the same thing with the break-out board, connecting any number of on/off "switches" in parallel, and get notification when any one of them changes state.
  • Miguel BuenrostroMiguel Buenrostro
    Vote Up1Vote Down
    Gerry, thanks for the info!

    When you say "connecting any number of on/off 'switches' in parallel" to the breakout board, would that involve some sort of adapter, or would all the sensor plug directly into the breakout board? So say I have 3 magnetic sensors, would the breakout board have 3 physical lines/inputs into each of the 3.3v/IN/GND?
  • Miguel BuenrostroMiguel Buenrostro
    Vote Up1Vote Down
    Bill, would this magnetic sensor work for the scenario(s) you described?

    http://www.tyelectronics.com/index.php?main_page=product_info&products_id=61
    It says voltage 3.3V-5V, but since I'm not familiar with all of this, will it cause issues since it can go over 3.3V? If this wouldn't work, do you know where I can find one that will?
  • Bill SpencerBill Spencer
    Vote Up1Vote Down
    After more reading about the digital magnetic sensor Miguel asked about, I'm not sure it will work with the twine. It's a sensor with active circuits, providing a digital output, and may not provide the correct open/closed interface that twine expects. I would stick with a simple magnetic reed switch like the ones sold for home security systems.

    By the way, that digital sensor is available with a lot of other robotic parts from DFRobot.com. Lots of interesting stuff there.
  • Gerry MuellerGerry Mueller
    Vote Up0Vote Down
    See the on line manual for the breakout board to see how to wire any number of passive switches in parallel using a relay or a cheap transistor
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