Wake Up Receiver for Battery Powered Nodes?

  • Hi Everyone,
    I'm new to MySensors and I just setup a two node NRF24 network this past weekend, using a ESP based bridge and two Arduino UNO nodes. So far, I'm only posting temperature/humidity data from DHT11 sensors connected to my nodes, but I have big plans. If anyone who support MySensors is reading this, thanks a ton for your work! With my future setup, I want to add many battery powered nodes throughout my home and I'm facing issues related to the receive current draw of the NRF24 chips.

    I did some research and talked to some of my peers that do RF design at work and it looks like it's not uncommon for battery powered nodes to have an additional receiver that is used only for "wake up". The idea is, this low power receiver is always on and it "wakes up" the micro-controller/other hardware (NRF24), when it receives a signal from a transmitter (in this case, a signal the network bridge?). I found a chip that supports this feature, the AS3930 ($5.00). My thoughts are, I want to have battery powered nodes that have very low latency to commands but last a very long time on battery power. Has anyone else experimented with “Wake Up Receivers” for battery powered nodes?

  • Mod

    @surgetransient welcome to the community! Really nice that you enjoy MySensors.

    I have not seen this type of receiver before, but the use case (battery powered actuator node with low latency) has been discussed extensively. smartSleep was created to handle the use case, but a wake-up receiver could be a better solution. From the AS3930 spec: Low power listening mode (1.37µA) - this is quite impressive.

    What kind of sender would be needed? What range does it have? From what I read, it looks like the main application is RFID which has a range of centimeters to decimeters - way too little for most MySensors applications.

  • @mfalkvidd thanks for the input! I mainly write software now and it's been a while since my RF classes, but I would think some form of transmitter with sufficient power output would work. I think the biggest challenge would be the antenna size at 100kHz. I'll do some more research and report back if I come up with something practical.

  • So I did more digging and I found the AS3933 IC. They have reference designs/demo boards (very expensive!). Still not sure about range, but it looks like this is possible.

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