Power On or Off Indicator LED - 3v to ground (gnd) or Through Other Pins

I am trying to add an On/Off indicator light to my Boron unit. (I know there are on board flashing lights as it cycles, but I am still interested in having the external on/off indicator.

My first thought is to have a 3v led connected to ground. This works immediately when the unit is activated. However, I have read that there are regulator issues when powering anything from the 3v pin. Particle documentation states is “SHOULD” be okay as long as the current draw is below 150 mA . Is this correct?

Note- Placing code on the unit and activating an LED via code only happens after the unit finds a signal and starts the code.

Any other suggestions or options are appreciated.

You can power an LED from 3V3 and GND, with the appropriate current limiting resistor, for all reasonably-sized LED indicators.

Using SYSTEM_THREAD(ENABLED) allows your code to run before connecting to the cloud. However, GPIO on the Boron are limited to 2 mA or 10mA if you enable high drive mode, so you can only use a small low-current LED on a GPIO.


I’ve read through the “SYSTEM_THREAD(ENABLED)” documentation, and have a follow-up question. What function or call can be used to recognize that the unit has connected to the cloud and the “set up” loop can move forward?


And here is how you can “wait” for the connection

If you don’t need the Particle cloud but merely a network connection you could check for Network.ready() (or more specificaly WiFi.ready() / Cellular.ready() / Ethernet.ready())

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