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balintmaci
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Default Deep sleep

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
 
0kando0
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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.
 
balintmaci
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Originally Posted by 0kando0 View Post
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...
 
0kando0
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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.
 
ar31791
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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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balintmaci
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Originally Posted by ar31791 View Post
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.
 
Bruce Lee
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By the way... you can check the deep sleep process with the app CPU spy.

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Erebus671
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Originally Posted by ar31791 View Post
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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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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Bruce Lee
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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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That's what I meant to say.... thanks

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