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Deep sleep

OP balintmaci

22nd April 2012, 09:34 PM   |  #1  
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So in neutrino thread we were arguing about deepsleep mode, anyone can check it out, i decided to start a thread about it here, because i don't want to OT in dev thread.

The question is, what sleep mode really does.
Does it turn off the CPU completely or just enters it into a low freq state?
i know that it turns off most stuff but this is about CPU now.

comments are welcome, but possible show proof
23rd April 2012, 12:29 PM   |  #2  
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Hmm..

After seeing this I tried doing a quick google search. I always thought the cpu just entered a low frequency state but maybe it shuts off completely?

http://developer.android.com/referen...stemClock.html

"This clock stops when the system enters deep sleep (CPU off, display dark, device waiting for external input), but is not affected by clock scaling, idle, or other power saving mechanisms."


Either way bump for interest.
23rd April 2012, 04:16 PM   |  #3  
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Quote:
Originally Posted by 0kando0

Hmm..

After seeing this I tried doing a quick google search. I always thought the cpu just entered a low frequency state but maybe it shuts off completely?

http://developer.android.com/referen...stemClock.html

"This clock stops when the system enters deep sleep (CPU off, display dark, device waiting for external input), but is not affected by clock scaling, idle, or other power saving mechanisms."


Either way bump for interest.

yeah we've found that link too
appearently wasn't enough for the others...
23rd April 2012, 05:39 PM   |  #4  
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Admittedly weak source. Surprising lack of information for a quick search though.

I also found this conversation.

http://groups.google.com/group/andro...&lnk=ol&&pli=1

They mention deep sleep a few times and nobody contradicts the idea that your cpu shuts off.

---------- Post added at 10:39 AM ---------- Previous post was at 10:36 AM ----------

I did a search for all posts containing deep sleep.

http://developer.android.com/search.html#q=deep sleep&t=0

85 results if anybody wants to dig a little bit.
23rd April 2012, 11:44 PM   |  #5  
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Today, most off our digital mobile technology is made using CMOS technology. This construction of logic gates only draws power when switching (when clocked). The CPU is made up of thousands of cmos logic gates. when the clock is stopped, the CPU holds it's current state. This is what deep sleep mode does. This is similar to your computer going into sleep or hibernation mode. simply stopping the system clock allows for nearly zero power consumption and retention of state.

(I am a computer engineer)

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24th April 2012, 11:16 AM   |  #6  
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Quote:
Originally Posted by ar31791

Today, most off our digital mobile technology is made using CMOS technology. This construction of logic gates only draws power when switching (when clocked). The CPU is made up of thousands of cmos logic gates. when the clock is stopped, the CPU holds it's current state. This is what deep sleep mode does. This is similar to your computer going into sleep or hibernation mode. simply stopping the system clock allows for nearly zero power consumption and retention of state.

(I am a computer engineer)

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thank you very much sir.
24th April 2012, 10:53 PM   |  #7  
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By the way... you can check the deep sleep process with the app CPU spy.

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25th April 2012, 06:31 AM   |  #8  
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Quote:
Originally Posted by ar31791

Today, most off our digital mobile technology is made using CMOS technology. This construction of logic gates only draws power when switching (when clocked). The CPU is made up of thousands of cmos logic gates. when the clock is stopped, the CPU holds it's current state. This is what deep sleep mode does. This is similar to your computer going into sleep or hibernation mode. simply stopping the system clock allows for nearly zero power consumption and retention of state.

(I am a computer engineer)

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Thanks for that, I'm a technician, not an engineer, so my access to that type of info is slightly limited, do you think you could provide some more in-depth details? Much appreciated.

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25th April 2012, 06:35 AM   |  #9  
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Quote:
Originally Posted by Voelker45

By the way... you can check the deep sleep process with the app CPU spy.

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CPU spy only tells you if it has been used and how much it has been used, nothing more.

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25th April 2012, 08:28 PM   |  #10  
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Quote:
Originally Posted by Erebus671

CPU spy only tells you if it has been used and how much it has been used, nothing more.

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That's what I meant to say.... thanks

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