Geekzone: technology news, blogs, forums
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.

5294 posts

Uber Geek
+1 received by user: 2147

Topic # 159853 15-Dec-2014 09:56
Send private message

Obviously if I take the battery out it is but .... if my smart phone (GS4) is really off when 'shut down' how does it detect a long press of the main key as a signal to switch on?  Surely some part of the phone activated and monitoring the key for a long press?

No particular point to this question I'm just curious.


Create new topic
563 posts

Ultimate Geek
+1 received by user: 89

  Reply # 1197606 15-Dec-2014 10:32
Send private message

Capacitor? 555 timer?

12151 posts

Uber Geek
+1 received by user: 3965

Lifetime subscriber

  Reply # 1197618 15-Dec-2014 10:48
Send private message

It's a good question. Especially for phones like the iPhone where the battery cannot be removed by the user.


2547 posts

Uber Geek
+1 received by user: 1238

Lifetime subscriber

  Reply # 1197666 15-Dec-2014 11:59
Send private message

Yes, there is always some circuitry (e.g. a Real Time Clock) which is 'alive', even when the power is 'off'. That applies to all kinds of appliances and computers and so on. Often, this RTC circuit (which may be a microprocessor or microcontroller) will have life-or-death power over the main processor, and will wake it in response to receiving a 'power-on' signal from the user.

Typically a phone will have a super-cap or similar to keep power on for stuff like a RTC while the battery is changed. I don't know how long the super-cap would last, but I'd guess it would be minutes rather than hours.

1370 posts

Uber Geek
+1 received by user: 348

  Reply # 1197675 15-Dec-2014 12:09
Send private message

If you watch TV then you'd have the impression that all phones are GPS trackable even when off! :-)

But yes some parts are still live while there is a battery in it, as you mention the process to turn it fully on when you press the power button, the clock (so it can keep time and wake the phone on an alarm) and probably other gizmos as well.

3100 posts

Uber Geek
+1 received by user: 1570

  Reply # 1197687 15-Dec-2014 12:26
Send private message

Skynet...once activated it cannot be shut down!!!

Always be yourself, unless you can be Batman, then always be the Batman

21620 posts

Uber Geek
+1 received by user: 4432


  Reply # 1197733 15-Dec-2014 13:40
Send private message

There is a special part that monitors the power button, both to power on, and to force a reset of the main processor on a super long hold of the button for when the main processor locks up.


Create new topic

Twitter »

Follow us to receive Twitter updates when new discussions are posted in our forums:

Follow us to receive Twitter updates when news items and blogs are posted in our frontpage:

Follow us to receive Twitter updates when tech item prices are listed in our price comparison site:

Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.

Geekzone Live »

Our community of supporters help make Geekzone possible. Click the button below to join them.

Support Geezone on PressPatron

Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.

Alternatively, you can receive a daily email with Geekzone updates.