Battery usage of analogWrite(LED1, 0.25) vs LED1.write()

[espruino-discuss]

Posted at 2017-04-11 by Drarok

I was wondering, given that there's hardware PWM (I think?) on the Puck, does that use more power than simply running the LED at full bright, or does the reduced LED draw make up for whatever power requirements the PWM has?

Slightly odd question, I know. :)

[gfwilliams]

Posted at 2017-04-12 by @gfwilliams

That's a hard one - you'd have to test - I think it'll depend on the brightness. analogWrite(LED1,0.99) will certainly use more power than digitalWrite(LED1,1).

There is hardware PWM, but it requires the high-speed oscillator to be on - which will use power even though the processor is asleep.

If you want a dim glow, by far the most power efficient way would be doing pinMode(LED1,"input_pullup") since then everything can be properly asleep.