Advice on waking up the LoPy4

  • I'm building a device that will have a button that activates the LoPy to send a short LoRa transmission. The device must run on non-rechargeable, inexpensive battery for at least a couple of years. The button will only be pushed under unusual emergency circumstances, which means probably never. The device will have to wake up every hour to send a transmission signifying it is still working. So the battery will be expended by these hourly transmissions, not by the pushbutton. I want the system to go into ultra-low-power mode when it's not transmitting. What's the best approach to this? I've heard that maybe a real time clock can do the hourly wakeup, and that the pushbutton could apply Vcc to an interrupt to wakeup the device as well. Is this the case? Thanks.

  • @jcaron Ok thanks, appreciate the response and will keep all this in mind. Might reduce the frequency of the call-in's to once a day which of course would decrease power consumption appreciably.

  • On the LoPy 4, you can just use machine.pin_deepsleep_wakeup() and machine.deepsleep() to achieve exactly that.

    Not sure you can really last a couple of years like that though. Also you need a battery capable of delivering the current spike required during boot, and need to take into account battery self-discharge. Settings of the LoRaWAN network can also adversely affect how long the battery will last.

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