Will alarm clock apps be able to wake up the phone when it's off?

As the title says, will i be able to completely turn off my phone and still have a working alarm clock in the morning? Like in the good old days… :smiley:


No. (bloddy character limit)


Ok :frowning: thanks…

That was a thing??? Whoa!

Why would you want this though? Phones usually use a lot of energy to start up compared to just being on

Will it work when the phone is suspended (this works on Android)?

Wake up Linux system from sleep/hibernation mode
Maybe this can do the job if it’s some king of RTC in the Librem 5

@rekotc f the phone is completely off how can be turned on? I guess Android phones can do that because still something working in the background but I’m not sure to be truth.

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@Raggelen @uzanto I remember my old nokias being able to turn themselves on early morning to wake me up :smiley: I’ve always thought that during the night there is no need to keep the phone on, since i’m sleeping.


I’m confused, why not just put the phone in airplane mode, or just flick all the killswitches on the librem 5?

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@Raggelen Sure, i could do that, as i do now on my android phone. But i still dream of being able to turn off the damn thing while keeping the alarm clock set :smiley: Not a tragedy, I’ll survive :wink:

I just don’t understand why haha. Why would you want to turn it off?

@Raggelen LOL I have this weird way of thinking: if i don’t use it (because i’m sleeping or for any other reason) i don’t want it to waste energy at all :stuck_out_tongue:


How is the phone going to know what time it is (so it can wake up at the appropriate time) if it isn’t using any energy? I can understand wanting to be frugal, but they’re engineers, not magicians.

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In order to save energy, assuming that the capacity of the battery will be too little for the hardware.

I’m not an engineer, but i remember my old nokias being able to do just that. But no worries, i’ll happily use my librem-5 anyway :smiley:

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I had no idea that modern phones couldn’t do this! But, then again, I never really considered the complexity of it.

I rarely use my phone as an alarm clock, but it’s an old one with an alarm that works when the phone is off. Obviously “off” in this context just means it’s in a very low power state, not completely off. Maybe the main processor itself goes into a low power mode, or maybe it halts entirely and hands off alarm clock responsibility to a secondary, low-power management controller type thing that can restart the main processor when someone presses the power button or the alarm time comes around.

Certainly you get some screen flicker and a bit of a delay as it appears to boot up before the alarm sounds. If I recall correctly, it boots up a few seconds before the alarm time, so that the alarm itself is precisely on time. I suppose an Android device would need to boot up maybe five minutes in advance, to err on the side of caution, especially if third party alarm clock apps were involved.

I don’t really care whether the Librem 5 has this feature, given how little I’ll use it.


Schematics for the developer kit include separate real time clock, capable of raising an interrupt. I can’t tell if that interrupt is able to wake up the CPU + RAM + everything else needed to sound the alarm. My bet is that it is possible, but simply won’t be supported in software from day 1. Then again, I tend to loose most of my bets :slight_smile:


Yeah I remember those days too. Everyone posting here would rather give you advice rather than answering your question it seems.

Well, i got a (short) answer, i was just curious about this specific feature. I’ll keep using my classic alarm clock as i do every day :wink:

The part that makes this tricky to answer is the definition of “completely”. If your phone woke up, then it was not 100% off. It was using some energy to run the Real Time Clock.

For the L5, I’ve set up a tracking issue: https://source.puri.sm/Librem5/OS-issues/issues/120

We encourage all interested L5 and devkit owners to take this on :slight_smile: It’s quite likely that along the way you’re going to bring overall energy usage improvements.