PPG sensor LED turns off automatically

Posted on Tue 17th, May 2022

• #1

nravanelli

I've been playing around with the BangleJS2 and PPG heart rate monitor. I've noticed when using the Recorder App that if the PPG sensor is not reading anything, the green LEDs turn off, and will not come back on when placed on wrist.... Is there a way to continue attempting or refreshing the PPG to try and find a pulse again?
• #2

Gordon

Are you on the normal 2v13 firmware? This was an issue with the latest bangles and got fixed a few weeks ago so if you try a 'cutting edge' build it should work fine and start the HRM as soon as it detects skin nearby.
• #3

nravanelli in reply to @Gordon

Well that would explain it... updating to 'cutting edge' now. I wrote a callback function to 'restart' the PPG sensor (stop(),start()) after a handful of zero/NaN HR values and to only restart when accelerometer detected motion ... no point wasting battery if the watch is sitting on the table.

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