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Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
@Gordon
Hi!
By default Bluetooth devices send out an 'advertisement' to say they're there (and allow them to be connected to). It sounds like it's pretty much exactly what you want.
By default Puck.js advertises every 375ms in such a way that it can be connected to - this draws 40uA (full info here: https://www.espruino.com/Puck.js#power-consumption)
Just doing
NRF.setAdvertising({},{connectable:false, scannable:false});drops that to 22uA thoughAnd telling it to advertise only every 2 seconds with
NRF.setAdvertising({},{connectable:false, scannable:false, interval:2000});drops the power usage very low below 10uA. 200mA/10uA = 20,000 hours (over 2 years hopefully)There are diminishing returns in power usage from lowering the advertising interval further, and since an advertisement isn't guaranteed to get through it helps to have a lot more of them sent out than you need.
There's some info on receiving those advertisements on different things at https://www.espruino.com/BLE+Advertising as well.
Hopefully that should be a good start!