Re: CL1B power distribution

2009-05-01 Thread C. Scott Ananian
On Tue, Apr 28, 2009 at 8:51 PM, John Watlington w...@laptop.org wrote:

 All of our LEDs are dual (one on the inside and one on the outside).
 Instead of running these in parallel, and throwing away the extra
 voltage, I run them in series directly from the battery voltage
 (ever notice that their brightness changes when you plug in
 the charger ?)

Is this a change to the Gen 1 design?  I remember studying the Gen 1
schematic and convincing myself it could be done if only we could run
an additional wire to an input pin.  You don't have to drive the LED
directly from the microcontroller; you only need to be able to switch
it and sense the voltage while watching the time.  The photocurrent
causes the inherent capacitance to discharge faster (or slower?  I
forget).  The time scale is really short, but that's no problem for
today's chips.  You could parallel a (very small) capacitor across the
LED to make it more sensitive.

Any of the four existing LEDs would be appropriate: wireless A and
B, battery, or power.  Heck, the two separate wireless LEDs cause
more confusion then they're worth anyway, you might as well get rid of
one and use the LED there only for input...
 --scott

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Re: CL1B power distribution

2009-05-01 Thread Benjamin M. Schwartz
John Watlington wrote:
 the LED trick has the advantage of not requiring a change to the case,
 just a single additional drive pin to be able to run it as a detector.
 
 And where would you place said detector LED, without modifying the  
 case ?

While we're bikeshedding this to death, I'll put in my vote for reusing
the camera activity LED.  It's well isolated from other light sources, and
it's rarely on. Whenever the camera is off, it can be used a
photodetector.  To retain the security guarantee that the light is on when
the camera is on, it might be necessary to put a diode across the camera's
power supply, so that they can be reverse-biased together.

If only we could get another hole in the case.

--Ben



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Re: CL1B power distribution

2009-05-01 Thread david

On Fri, 1 May 2009, Jameson Quinn wrote:


I like the idea, but wouldn't light transmission inside the case, from the
other LED's, screw this up?


possibly, how much leakage is there between the LEDs?

David Lang


(btw, wikipedia says more light = faster backwards discharge)


Heck, the two separate wireless LEDs cause

more confusion then they're worth anyway, you might as well get rid of
one and use the LED there only for input...



+1
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Re: CL1B power distribution

2009-05-01 Thread david
On Fri, 1 May 2009, Benjamin M. Schwartz wrote:

 John Watlington wrote:
 the LED trick has the advantage of not requiring a change to the case,
 just a single additional drive pin to be able to run it as a detector.

 And where would you place said detector LED, without modifying the
 case ?

 While we're bikeshedding this to death, I'll put in my vote for reusing
 the camera activity LED.  It's well isolated from other light sources, and
 it's rarely on. Whenever the camera is off, it can be used a
 photodetector.  To retain the security guarantee that the light is on when
 the camera is on, it might be necessary to put a diode across the camera's
 power supply, so that they can be reverse-biased together.

my understanding is that currently the camera and mic LEDs are hard-wired 
to those devices, not controlled independantly (to make sure that it's not 
possible to activate those devices without activating the LED)

the power LED is well seperated from everything else, has a fairly large 
opening in the case to let light in, so it would seem to be a good option.

at least one article indicated that this could be done with an LED that 
was otherwise on without the user noticing (comments were made that in the 
dark the delay could become noticable, but that could be solved by setting 
a max count to wait for)

David Lang

 If only we could get another hole in the case.

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Re: CL1B power distribution

2009-04-28 Thread C. Scott Ananian
On Sat, Apr 25, 2009 at 12:12 AM, John Watlington w...@laptop.org wrote:
 This is the current power distribution diagram for A-phase CL1B, identifying
 what we can power, when, and how.

I wonder if one could easily support running an LED backwards as an
ambient light monitor in Gen 1.5 - it seems that automatically
powering off the backlight in bright sunlight would lead to a lot of
power savings for most young users.
 --scott

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Re: CL1B power distribution

2009-04-28 Thread James Cameron
On Tue, Apr 28, 2009 at 10:15:47AM -0400, C. Scott Ananian wrote:
 I wonder if one could easily support running an LED backwards as an
 ambient light monitor in Gen 1.5 - it seems that automatically
 powering off the backlight in bright sunlight would lead to a lot of
 power savings for most young users.

I agree that an ambient light detector and automatic adjustment of
backlight would save power.  It would happen transparently, magically.

But I don't think the LEDs are often specified in terms of their ambient
light detection properties.

Perhaps it would be better to use a photodiode, or light dependent
resistor.

Then there's the spectrum of light being received.

Then there's reflection from the laptop display itself to consider.

I recall we also once had a discussion on whether the camera could be
used as an ambient light detector.

-- 
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Re: CL1B power distribution

2009-04-28 Thread david
On Wed, 29 Apr 2009, James Cameron wrote:

 On Tue, Apr 28, 2009 at 10:15:47AM -0400, C. Scott Ananian wrote:
 I wonder if one could easily support running an LED backwards as an
 ambient light monitor in Gen 1.5 - it seems that automatically
 powering off the backlight in bright sunlight would lead to a lot of
 power savings for most young users.

 I agree that an ambient light detector and automatic adjustment of
 backlight would save power.  It would happen transparently, magically.

 But I don't think the LEDs are often specified in terms of their ambient
 light detection properties.

 Perhaps it would be better to use a photodiode, or light dependent
 resistor.

 Then there's the spectrum of light being received.

 Then there's reflection from the laptop display itself to consider.

 I recall we also once had a discussion on whether the camera could be
 used as an ambient light detector.

you don't want to have to run the camera to detect the light (this will 
eat far more power than you would save)

the LED trick has the advantage of not requiring a change to the case, 
just a single additional drive pin to be able to run it as a detector.

David Lang
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Re: CL1B power distribution

2009-04-28 Thread John Watlington

On Apr 28, 2009, at 7:31 PM, da...@lang.hm wrote:

 On Wed, 29 Apr 2009, James Cameron wrote:

 On Tue, Apr 28, 2009 at 10:15:47AM -0400, C. Scott Ananian wrote:
 I wonder if one could easily support running an LED backwards as an
 ambient light monitor in Gen 1.5 - it seems that automatically
 powering off the backlight in bright sunlight would lead to a lot of
 power savings for most young users.

 I agree that an ambient light detector and automatic adjustment of
 backlight would save power.  It would happen transparently,  
 magically.

 But I don't think the LEDs are often specified in terms of their  
 ambient
 light detection properties.

 Perhaps it would be better to use a photodiode, or light dependent
 resistor.

 Then there's the spectrum of light being received.

 Then there's reflection from the laptop display itself to consider.

 I recall we also once had a discussion on whether the camera could be
 used as an ambient light detector.

 you don't want to have to run the camera to detect the light (this  
 will
 eat far more power than you would save)

 the LED trick has the advantage of not requiring a change to the case,
 just a single additional drive pin to be able to run it as a detector.

And where would you place said detector LED, without modifying the  
case ?

(I have the pin...)

wad

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Re: CL1B power distribution

2009-04-28 Thread david
On Tue, 28 Apr 2009, John Watlington wrote:

 On Apr 28, 2009, at 7:31 PM, da...@lang.hm wrote:

 On Wed, 29 Apr 2009, James Cameron wrote:
 
 On Tue, Apr 28, 2009 at 10:15:47AM -0400, C. Scott Ananian wrote:
 I wonder if one could easily support running an LED backwards as an
 ambient light monitor in Gen 1.5 - it seems that automatically
 powering off the backlight in bright sunlight would lead to a lot of
 power savings for most young users.
 
 I agree that an ambient light detector and automatic adjustment of
 backlight would save power.  It would happen transparently, magically.
 
 But I don't think the LEDs are often specified in terms of their ambient
 light detection properties.
 
 Perhaps it would be better to use a photodiode, or light dependent
 resistor.
 
 Then there's the spectrum of light being received.
 
 Then there's reflection from the laptop display itself to consider.
 
 I recall we also once had a discussion on whether the camera could be
 used as an ambient light detector.
 
 you don't want to have to run the camera to detect the light (this will
 eat far more power than you would save)
 
 the LED trick has the advantage of not requiring a change to the case,
 just a single additional drive pin to be able to run it as a detector.

 And where would you place said detector LED, without modifying the case ?

 (I have the pin...)

use one of the existing LED's.

I would guess probably the power LED as it has the largest opening (and so 
would probably be the best choice for detecting light)

David Lang
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Re: CL1B power distribution

2009-04-28 Thread david
On Tue, 28 Apr 2009, da...@lang.hm wrote:

 On Tue, 28 Apr 2009, John Watlington wrote:

 On Apr 28, 2009, at 7:31 PM, da...@lang.hm wrote:

 On Wed, 29 Apr 2009, James Cameron wrote:

 On Tue, Apr 28, 2009 at 10:15:47AM -0400, C. Scott Ananian wrote:
 I wonder if one could easily support running an LED backwards as an
 ambient light monitor in Gen 1.5 - it seems that automatically
 powering off the backlight in bright sunlight would lead to a lot of
 power savings for most young users.

 I agree that an ambient light detector and automatic adjustment of
 backlight would save power.  It would happen transparently, magically.

 But I don't think the LEDs are often specified in terms of their ambient
 light detection properties.

 Perhaps it would be better to use a photodiode, or light dependent
 resistor.

 Then there's the spectrum of light being received.

 Then there's reflection from the laptop display itself to consider.

 I recall we also once had a discussion on whether the camera could be
 used as an ambient light detector.

 you don't want to have to run the camera to detect the light (this will
 eat far more power than you would save)

 the LED trick has the advantage of not requiring a change to the case,
 just a single additional drive pin to be able to run it as a detector.

 And where would you place said detector LED, without modifying the case ?

 (I have the pin...)

 use one of the existing LED's.

 I would guess probably the power LED as it has the largest opening (and so
 would probably be the best choice for detecting light)

by the way, for those who are wondering what we are talking about. this 
post summarizes how it works (in the comments at 
http://www.evilmadscientist.com/article.php/nightlight, posted by 
anonymous)

if you happen to have a microchip around, just that and an LED and a 
battery will do.
Similar to those LED throwies that have the microchip sitting on the LED's 
legs, the same concept could be used.

Have the microchip reverse bias the LED and then swap the anode to be a 
high impedance input, then loop over checking the value of the LED, it 
should go high after x loops, depending on how much light lands on the 
LED.

In the dark, it will take longer (less light - less photocurrent) so if 
you count how many loops it took and then only turn the LED on when the 
loop count is above the threshhold, you could have the same circuit in 
only 2 components and the battery.

However, if it got very dark the flashing off when the LED is reverse 
biased would probably take long enough that it would be noticeable - you 
could try having a maximum the loop will go up to before it assumes it's 
dark and stops there.
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Re: CL1B power distribution

2009-04-28 Thread david
On Tue, 28 Apr 2009, John Watlington wrote:

 On Apr 28, 2009, at 8:16 PM, da...@lang.hm wrote:

 On Tue, 28 Apr 2009, John Watlington wrote:
 
 On Apr 28, 2009, at 7:31 PM, da...@lang.hm wrote:
 
 On Wed, 29 Apr 2009, James Cameron wrote:
 On Tue, Apr 28, 2009 at 10:15:47AM -0400, C. Scott Ananian wrote:
 I wonder if one could easily support running an LED backwards as an
 ambient light monitor in Gen 1.5 - it seems that automatically
 powering off the backlight in bright sunlight would lead to a lot of
 power savings for most young users.
 I agree that an ambient light detector and automatic adjustment of
 backlight would save power.  It would happen transparently, magically.
 But I don't think the LEDs are often specified in terms of their ambient
 light detection properties.
 Perhaps it would be better to use a photodiode, or light dependent
 resistor.
 Then there's the spectrum of light being received.
 Then there's reflection from the laptop display itself to consider.
 I recall we also once had a discussion on whether the camera could be
 used as an ambient light detector.
 you don't want to have to run the camera to detect the light (this will
 eat far more power than you would save)
 the LED trick has the advantage of not requiring a change to the case,
 just a single additional drive pin to be able to run it as a detector.
 
 And where would you place said detector LED, without modifying the case ?
 
 (I have the pin...)
 
 use one of the existing LED's.

 I have no intention to use one of the existing LEDs.   They don't run off 
 logic level
 voltages for power reasons, and adding switches would be more expensive than
 dedicating an LED.

 Hence my question...

if it's not reasonable to use an existing LED, then I guess this idea 
will need to be scrapped. I think the people proposing the idea were 
figuring that in the hardware update one of the LEDs could be re-wired so 
that it could be run directly (between two pins, the pin that currently 
controls it, and a new one)

I will admit to not understanding the power reasons comment. is it that 
the LEDs in use draw more power than you want to run through the control 
chips?

David Lang
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Re: CL1B power distribution

2009-04-28 Thread John Watlington

All of our LEDs are dual (one on the inside and one on the outside).
Instead of running these in parallel, and throwing away the extra
voltage, I run them in series directly from the battery voltage
(ever notice that their brightness changes when you plug in
the charger ?)

Cheers,
wad

On Apr 28, 2009, at 8:42 PM, da...@lang.hm wrote:

 On Tue, 28 Apr 2009, John Watlington wrote:

 On Apr 28, 2009, at 8:16 PM, da...@lang.hm wrote:

 On Tue, 28 Apr 2009, John Watlington wrote:
 On Apr 28, 2009, at 7:31 PM, da...@lang.hm wrote:
 On Wed, 29 Apr 2009, James Cameron wrote:
 On Tue, Apr 28, 2009 at 10:15:47AM -0400, C. Scott Ananian wrote:
 I wonder if one could easily support running an LED backwards  
 as an
 ambient light monitor in Gen 1.5 - it seems that automatically
 powering off the backlight in bright sunlight would lead to a  
 lot of
 power savings for most young users.
 I agree that an ambient light detector and automatic  
 adjustment of
 backlight would save power.  It would happen transparently,  
 magically.
 But I don't think the LEDs are often specified in terms of  
 their ambient
 light detection properties.
 Perhaps it would be better to use a photodiode, or light  
 dependent
 resistor.
 Then there's the spectrum of light being received.
 Then there's reflection from the laptop display itself to  
 consider.
 I recall we also once had a discussion on whether the camera  
 could be
 used as an ambient light detector.
 you don't want to have to run the camera to detect the light  
 (this will
 eat far more power than you would save)
 the LED trick has the advantage of not requiring a change to  
 the case,
 just a single additional drive pin to be able to run it as a  
 detector.
 And where would you place said detector LED, without modifying  
 the case ?
 (I have the pin...)
 use one of the existing LED's.

 I have no intention to use one of the existing LEDs.   They don't  
 run off logic level
 voltages for power reasons, and adding switches would be more  
 expensive than
 dedicating an LED.

 Hence my question...

 if it's not reasonable to use an existing LED, then I guess this  
 idea will need to be scrapped. I think the people proposing the  
 idea were figuring that in the hardware update one of the LEDs  
 could be re-wired so that it could be run directly (between two  
 pins, the pin that currently controls it, and a new one)

 I will admit to not understanding the power reasons comment. is it  
 that the LEDs in use draw more power than you want to run through  
 the control chips?

 David Lang

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Re: CL1B power distribution

2009-04-28 Thread david
On Tue, 28 Apr 2009, John Watlington wrote:

 All of our LEDs are dual (one on the inside and one on the outside).
 Instead of running these in parallel, and throwing away the extra
 voltage, I run them in series directly from the battery voltage
 (ever notice that their brightness changes when you plug in
 the charger ?)

hmm, how much power are we talking about saving compared to running them 
in parallel of a chip?

over the life of a battery, how much would the backlight need to be turned 
off to save as much power?

note that if it's really dark, it may be reasonable to dim the backlight, 
so the savings aren't just in bright light.

do we think that we could gain that much time on average?

how about possible savings from driving the LEDs at less than 100% duty 
cycle?

my gut feeling is that the difference in the power used in driving the 
LEDs from a chip would probably be countered in a very short time by the 
savings from being able to turn off the backlight LED array, and may even 
be able to be countered by just running all the indicator LEDs at lower 
duty cycles when the light is dim.

the only concern I would have is if you can run the two LEDs in parallel 
off of the chip directly.

David Lang

 Cheers,
 wad

 On Apr 28, 2009, at 8:42 PM, da...@lang.hm wrote:

 On Tue, 28 Apr 2009, John Watlington wrote:
 
 On Apr 28, 2009, at 8:16 PM, da...@lang.hm wrote:
 
 On Tue, 28 Apr 2009, John Watlington wrote:
 On Apr 28, 2009, at 7:31 PM, da...@lang.hm wrote:
 On Wed, 29 Apr 2009, James Cameron wrote:
 On Tue, Apr 28, 2009 at 10:15:47AM -0400, C. Scott Ananian wrote:
 I wonder if one could easily support running an LED backwards as an
 ambient light monitor in Gen 1.5 - it seems that automatically
 powering off the backlight in bright sunlight would lead to a lot of
 power savings for most young users.
 I agree that an ambient light detector and automatic adjustment of
 backlight would save power.  It would happen transparently, magically.
 But I don't think the LEDs are often specified in terms of their 
 ambient
 light detection properties.
 Perhaps it would be better to use a photodiode, or light dependent
 resistor.
 Then there's the spectrum of light being received.
 Then there's reflection from the laptop display itself to consider.
 I recall we also once had a discussion on whether the camera could be
 used as an ambient light detector.
 you don't want to have to run the camera to detect the light (this will
 eat far more power than you would save)
 the LED trick has the advantage of not requiring a change to the case,
 just a single additional drive pin to be able to run it as a detector.
 And where would you place said detector LED, without modifying the case 
 ?
 (I have the pin...)
 use one of the existing LED's.
 
 I have no intention to use one of the existing LEDs.   They don't run off 
 logic level
 voltages for power reasons, and adding switches would be more expensive 
 than
 dedicating an LED.
 
 Hence my question...
 
 if it's not reasonable to use an existing LED, then I guess this idea will 
 need to be scrapped. I think the people proposing the idea were figuring 
 that in the hardware update one of the LEDs could be re-wired so that it 
 could be run directly (between two pins, the pin that currently controls 
 it, and a new one)
 
 I will admit to not understanding the power reasons comment. is it that the 
 LEDs in use draw more power than you want to run through the control chips?
 
 David Lang

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Re: CL1B power distribution

2009-04-27 Thread Joel Stanley
Hello Wad,

On Sun, Apr 26, 2009 at 12:35, John Watlington w...@laptop.org wrote:

 On Apr 25, 2009, at 7:29 PM, p...@laptop.org wrote:

 - will we have (approximate) numbers at some point for how
   much power any given subsystem takes?  (e.g., for the
   above case, how much would powering down the kbd/tpad
   save?  this will inform decisions like how much effort
   is it worth?)
 I have estimates for the new sections, and we have numbers from
 Tinderbox for the portions that aren't changing (keyboard, touchpad,
 DCON, display).

Out of interest, will the new PCB layout be tinderbox-friendly?  Are
you planning to wire a 1.5 up?

Joel
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Re: CL1B power distribution

2009-04-27 Thread John Watlington

On Apr 27, 2009, at 6:11 AM, Joel Stanley wrote:

 Hello Wad,

 On Sun, Apr 26, 2009 at 12:35, John Watlington w...@laptop.org wrote:

 On Apr 25, 2009, at 7:29 PM, p...@laptop.org wrote:

 - will we have (approximate) numbers at some point for how
   much power any given subsystem takes?  (e.g., for the
   above case, how much would powering down the kbd/tpad
   save?  this will inform decisions like how much effort
   is it worth?)
 I have estimates for the new sections, and we have numbers from
 Tinderbox for the portions that aren't changing (keyboard, touchpad,
 DCON, display).

 Out of interest, will the new PCB layout be tinderbox-friendly?  Are
 you planning to wire a 1.5 up?

Tinderbox friendly and production friendly are different goals.
A-phase will be tinderbox friendly, but the resistors will be
going away before C-phase.

wad

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Re: CL1B power distribution

2009-04-27 Thread Chris Ball
Hi,

the most likely case i can think of involves being able to allow
USB input devices to remain alive during suspend (for wakeup
purposes), while powering down other devices (disks?) for power
savings.

Hm, I think the USB controller probably turns off by necessity in
suspend, as it does on the Geode, so I don't think keeping power
going to individual ports would achieve anything.

- Chris.
-- 
Chris Ball   c...@laptop.org
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Re: CL1B power distribution

2009-04-27 Thread pgf
chris wrote:
  Hi,
  
  the most likely case i can think of involves being able to allow
  USB input devices to remain alive during suspend (for wakeup
  purposes), while powering down other devices (disks?) for power
  savings.
  
  Hm, I think the USB controller probably turns off by necessity in
  suspend, as it does on the Geode, so I don't think keeping power
  going to individual ports would achieve anything.

perhaps i've been inferring something different than i should
from wad's initial mail, which said:

  - The SD slot and USB ports may be powered in suspend
   This is just in case some SD cards or USB devices don't
   handle being suspended aggressively.  We will support laptop
   wakeup on interrupt from any of these ports (SD or USB). 
   Under software control they may also be powered down during
   suspend.

paul
=-
 paul fox, p...@laptop.org
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Re: CL1B power distribution

2009-04-27 Thread Chris Ball
Hi,

perhaps i've been inferring something different than i should
from wad's initial mail, which said:

- The SD slot and USB ports may be powered in suspend

This is just in case some SD cards or USB devices don't handle
being suspended aggressively.  We will support laptop wakeup on
interrupt from any of these ports (SD or USB).  Under software
control they may also be powered down during suspend.

Sorry, you're right -- sounds like the VX855 does keep the USB
controller powered up in suspend and knows how to wake the CPU
from it.  That would have been useful the first time around.  :)

- Chris.
-- 
Chris Ball   c...@laptop.org
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Re: CL1B power distribution

2009-04-27 Thread Tiago Marques
On Sat, Apr 25, 2009 at 5:12 AM, John Watlington w...@laptop.org wrote:


 This is the current power distribution diagram for A-phase CL1B,
 identifying
 what we can power, when, and how.

 There are several power decisions that I believe need explaining up front:

 - The SD slot and USB ports may be powered in suspend
This is just in case some SD cards or USB devices don't handle being
 suspended
aggressively.   We will support laptop wakeup on interrupt from any
of these ports (SD or USB).   Under software control they may also be
 powered
down during suspend.

 - The audio codec remains partially powered in suspend
This is in order to support wakeup on jack insertion.  The codec
may be placed in a very low power state during suspend.

Sorry to ask, but is wakeup on jack insertion relevant for someting?
Also, on Gen1 I can still hear noise coming from the speakers when they're
muted, some current seems to still go through there. Has anyone ever found
out how much?
Best regards,
  Tiago Marques




 - Power efficiency was goal number #1, therefore there are some voltages
 with
  multiple sources: one for low power (suspend) and another for high power
 (run).

 Additional changes from Gen 1 include the ability to both measure DC input
 current
 and VIN voltage, as well as EC control over the current drawn from the DC
 input.
 The intent was to better support charging directly from solar panels.

 I'm sure there are mistakes --- let me know what you think.

 Cheers,
 wad


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Re: CL1B power distribution

2009-04-26 Thread David Woodhouse
On Sun, 2009-04-26 at 00:40 -0400, Benjamin M. Schwartz wrote:
 John Watlington wrote:
  Quick straw poll on how many people think it is useful enough have  
  individual control over the power supplied to each connector to raise the 
  cost  
  of the laptop by $0.15 ?
 
 Turning off a single port to which nothing is connected saves no power,
 right?  I don't see the appeal. 

It was nice that we could stagger the switching on of USB ports, to
avoid crashes due to power surges and resulting drops on the power rail.

How sure are you that we won't need similar workarounds in CL1B?

-- 
David WoodhouseOpen Source Technology Centre
david.woodho...@intel.com  Intel Corporation

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Re: CL1B power distribution

2009-04-26 Thread pgf
john wrote:
  Quick straw poll on how many people think it is useful enough
  have individual control over the power supplied to each
  connector to raise the cost of the laptop by $0.15 ?

the most likely case i can think of involves being able to allow
USB input devices to remain alive during suspend (for wakeup
purposes), while powering down other devices (disks?) for
power savings.

but any use usage sounds complicated enough that the current all or none
approach seems like it would cover most needs, and be relatively
easy to manage:
Leave USB devices powered on during idle suspend?  yes/no

paul
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Re: CL1B power distribution

2009-04-26 Thread James Cameron
On Sun, Apr 26, 2009 at 12:40:14AM -0400, Benjamin M. Schwartz wrote:
 Turning off a single port to which nothing is connected saves no power,
 right?  I don't see the appeal.  [...]

Sorry, perhaps I didn't explain myself adequately.

One of the uses of the laptop is in teaching of electronics and control
systems.  The current model has an analog input on the microphone
socket, but digital outputs require the addition of external USB
devices [1].

If there is a way to switch the 5V supply to individual USB ports, and
if that was exposed in software ... and it is $0.15, then the question
isn't really what power will it save but rather does the potential
use justify the cost?

The USB ports could then be used as switchable 5V sources, with the
current driving external devices directly, with the data leads of the
USB cable disconnected.

I don't know of anyone who plans to teach electronics and control
systems though.

--

[1] the analog input can be used as a digital output with additional
circuitry that detects the switching of the bias voltage, but that is
quite complex for a student to comprehend.

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Re: CL1B power distribution

2009-04-25 Thread John Watlington

On Apr 25, 2009, at 1:06 AM, Albert Cahalan wrote:

 John Watlington writes:

 - The SD slot and USB ports may be powered in suspend
  This is just in case some SD cards or USB devices don't handle
 being suspended
  aggressively.   We will support laptop wakeup on interrupt  
 from any
  of these ports (SD or USB).   Under software control they may
 also be powered
  down during suspend.

 There is value in making this per-port for the USB.

Funny, there was just a discussion of this on olpc-devel IRC.
There are several reasons not to use individual port switches:
- cost
- each USB port would then be limited to 2.5W (or 1.6W), instead
of the 5W possible now.
- cost
- cost

 - The audio codec remains partially powered in suspend
  This is in order to support wakeup on jack insertion.  The  
 codec
  may be placed in a very low power state during suspend.

 I would have expected power to be optional. The software doesn't
 always need to use this component during the run state

It can be placed in the same low power state during run (when
not used) as during suspend...

 Additional changes from Gen 1 include the ability to both measure
 DC input current and VIN voltage, as well as EC control over the
 current drawn from the DC input. The intent was to better support
 charging directly from solar panels.

 I hope that this will be available to activities like Measure.

Interesting point.  That would require extending the EC API, as they  
go to an A/D
not directly addressable by the main processor.

 Ideally updates could be frequent enough to pick up a waveform
 from an unrectified power supply. (spare audio channel?)


Cheers,
wad

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Re: CL1B power distribution

2009-04-25 Thread Richard A. Smith
 Additional changes from Gen 1 include the ability to both measure
 DC input current and VIN voltage, as well as EC control over the
 current drawn from the DC input. The intent was to better support
 charging directly from solar panels.
 I hope that this will be available to activities like Measure.
 
 Interesting point.  That would require extending the EC API, as they  
 go to an A/D
 not directly addressable by the main processor.
 
 Ideally updates could be frequent enough to pick up a waveform
 from an unrectified power supply. (spare audio channel?)

Don't have much in the way of EC cycles available.  Don't have much EC 
ram left to cache values either.

I can make the readings available via EC commands but each command takes 
a few ms to complete and back to back commands will have a few ms of 
delay as well.  I'm guessing you might be able to get a 20ms update rate.

The best method would be to leave indexed IO enable and tell the EC to 
quit reading from the ports.  Then you could use indexed IO to read the 
AD registers directly.  I'm not sure what update speed you can get that 
way but it should be pretty fast.

-- 
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Re: CL1B power distribution

2009-04-25 Thread pgf
smith wrote:
   Additional changes from Gen 1 include the ability to both measure
   DC input current and VIN voltage, as well as EC control over the
   current drawn from the DC input. The intent was to better support
   charging directly from solar panels.
   I hope that this will be available to activities like Measure.
   
   Interesting point.  That would require extending the EC API, as they  
   go to an A/D
   not directly addressable by the main processor.
   
   Ideally updates could be frequent enough to pick up a waveform
   from an unrectified power supply. (spare audio channel?)
  
  Don't have much in the way of EC cycles available.  Don't have much EC 
  ram left to cache values either.
  
  I can make the readings available via EC commands but each command takes 
  a few ms to complete and back to back commands will have a few ms of 
  delay as well.  I'm guessing you might be able to get a 20ms update rate.
  
  The best method would be to leave indexed IO enable and tell the EC to 
  quit reading from the ports.  Then you could use indexed IO to read the 
  AD registers directly.  I'm not sure what update speed you can get that 
  way but it should be pretty fast.

i would think Measure would be more interested in (short-term) averages
of voltage and current than in seeing power supply noise.

(will an XO even run properly from an unrectified, or even
unfiltered, supply?)

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Re: CL1B power distribution

2009-04-25 Thread Benjamin M. Schwartz
Richard A. Smith wrote:
 Ideally updates could be frequent enough to pick up a waveform
 from an unrectified power supply. (spare audio channel?)
 
 Don't have much in the way of EC cycles available.  Don't have much EC 
 ram left to cache values either.
 
 I can make the readings available via EC commands but each command takes 
 a few ms to complete and back to back commands will have a few ms of 
 delay as well.  I'm guessing you might be able to get a 20ms update rate.

That's not fast enough for much interesting signal processing, but it's
more than fast enough to do power metering.  Power metering while on
external power is something I've specifically been hoping for.

(So please consider adding this to the end of your very long EC TODO.)

--Ben



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Re: CL1B power distribution

2009-04-25 Thread Nate Ridderman
Any chance of getting schematics and PCB files this time around? I doubt you
renegotiated your contract with Quanta to allow for this, but it doesn't
hurt to ask.

Thanks,
Nate


On Sat, Apr 25, 2009 at 12:23 AM, John Watlington w...@laptop.org wrote:


 BTW, Gen 1.5 is the OLPC codename for the next revision of the XO.

 The official Quanta model number for the XO was CL1.
 The version of the XO with a new touchpad is CL1A.
 The Quanta model number for Gen 1.5 is CL1B.

 Cheers,
 wad

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Re: CL1B power distribution

2009-04-25 Thread Nate Ridderman
On Sat, Apr 25, 2009 at 10:05 AM, p...@laptop.org wrote:

 smith wrote:
Additional changes from Gen 1 include the ability to both measure
DC input current and VIN voltage, as well as EC control over the
current drawn from the DC input. The intent was to better support
charging directly from solar panels.
I hope that this will be available to activities like Measure.

 (will an XO even run properly from an unrectified, or even
 unfiltered, supply?)


Sure, if the right circuit is in place. A solar panel is rectified, which
makes things easier, but the power and voltage output is variable. It sounds
like Gen 1.5 will have charging FETs that you can gradually turn on/off to
limit the current flow through a path. Therefore, you can shut it off when
the charger isn't producing enough voltage or too much voltage for the
battery. It's hard to know exactly what's going on without seeing a
schematic and/or datasheet of the parts involved.

Thanks,
Nate
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Re: CL1B power distribution

2009-04-25 Thread Richard A. Smith
p...@laptop.org wrote:

 i would think Measure would be more interested in (short-term) averages
 of voltage and current than in seeing power supply noise.

 (will an XO even run properly from an unrectified, or even
 unfiltered, supply?)

Depends.  For gen 1.5 we have opened up the front end voltage 
specification a bit.  10.5 - 25V so anything bouncing around in that 
range should work.

-- 
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One Laptop Per Child
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Re: CL1B power distribution

2009-04-25 Thread Richard A. Smith
Benjamin M. Schwartz wrote:
 Richard A. Smith wrote:

 That's not fast enough for much interesting signal processing, but it's
 more than fast enough to do power metering.  Power metering while on
 external power is something I've specifically been hoping for.
 
 (So please consider adding this to the end of your very long EC TODO.)

Power metering is not optional. Its one of the first things I have to 
make work.

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Re: CL1B power distribution

2009-04-25 Thread pgf
wad wrote:
  
  This is the current power distribution diagram for A-phase CL1B,  
  identifying what we can power, when, and how.

wad -- 

a few questions -- for some i can guess at the answer, but better
to ask and be sure:

- if there are no USB devices inserted, is there an advantage
to powering down USB?  i.e., does it affect anything more
than the devices themselves?

- same question for SD?

- the keyboard/touchpad are now optionally powered in suspend
and run.  do you have a specific use case in mind?  the
only case i can think of is turning them off if we're
suspended and don't want their wakeups anyway.

- will we have (approximate) numbers at some point for how
much power any given subsystem takes?  (e.g., for the
above case, how much would powering down the kbd/tpad
save?  this will inform decisions like how much effort
is it worth?)

- i can't believe i'm asking this, but is it feasible to only
power half the ram?  would that help the power budget? 
i have no idea how that feature would be put to use.
or, perhaps more manageable:  half the flash?  if half
were unmounted when not in use, for instance.

- comparing with http://wiki.laptop.org/images/1/1c/Tinderbox_C2.png
(which i'm assuming is correct for XO-1), i see the audio
amp could be powered down before.  is that integral to the
HD Audio Codec box now?

- also comparing with that page, the RTC battery charger is
always on now, and wasn't before.  from our conversation
on IRC, it sounds like the circuit hasn't changed -- is that
right?  (and that it's less a charge circuit than an
anti-discharge circuit.)

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Re: CL1B power distribution

2009-04-25 Thread James Cameron
Reviewed the diagram carefully.  The only issue I spotted was that the
+5VSUS line into the RTC charger comes from a yellow switching voltage
regulator, despite the RTC charger coloured green.  Either it has to
come from somewhere else, or the RTC charger has to be yellow, or the
switching regulator has to be green.  ;-)

On the individual USB switching, can this be done between the USB chip
and the socket?  Being able to switch external devices would have
significant educational benefit in electronics teaching.  Perhaps only
switch two of the three, leaving the full capability on one.

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Re: CL1B power distribution

2009-04-25 Thread John Watlington

On Apr 25, 2009, at 7:29 PM, p...@laptop.org wrote:

 wad wrote:

 This is the current power distribution diagram for A-phase CL1B,
 identifying what we can power, when, and how.

 wad --

 a few questions -- for some i can guess at the answer, but better
 to ask and be sure:

 - if there are no USB devices inserted, is there an advantage
   to powering down USB?  i.e., does it affect anything more
   than the devices themselves?
I think most USB ports these days don't actually turn their drivers
on until they detect something inserted.   We can't really power
down the controller due to Via's requirements, but it should be in
the low single mW range unless it is being used.

 - same question for SD?
In the case of SD, a CMOS implementation shouldn't draw power
unless it is being used.

 - the keyboard/touchpad are now optionally powered in suspend
   and run.  do you have a specific use case in mind?  the
   only case i can think of is turning them off if we're
   suspended and don't want their wakeups anyway.
For example, there is no need to power the keyboard and touchpad in S3
with the lid closed or in ebook mode.

 - will we have (approximate) numbers at some point for how
   much power any given subsystem takes?  (e.g., for the
   above case, how much would powering down the kbd/tpad
   save?  this will inform decisions like how much effort
   is it worth?)
I have estimates for the new sections, and we have numbers from
Tinderbox for the portions that aren't changing (keyboard, touchpad,
DCON, display).

 - i can't believe i'm asking this, but is it feasible to only
   power half the ram?  would that help the power budget?
We have several options to test in A-phase with regards to obtaining
lower power from the RAM (lower speed, lower voltage) but are
waiting to see where we stand.

   i have no idea how that feature would be put to use.
   or, perhaps more manageable:  half the flash?  if half
   were unmounted when not in use, for instance.
Difficult to do, as a good flash controller stripes across both devices
to equalize wear and improve performance.   The 4GB machine will
just have a single NAND Flash chip.

 - comparing with http://wiki.laptop.org/images/1/1c/ 
 Tinderbox_C2.png
   (which i'm assuming is correct for XO-1), i see the audio
   amp could be powered down before.  is that integral to the
   HD Audio Codec box now?
The amp can still be powered down (that is the red part of the
HD audio codec).  The remainder of the codec remains powered
in suspend to implement wake-on-jack insert (although I have a
populate option to turn off the codec power in suspend if it isn't
low enough power --- the specs say it will be.)

 - also comparing with that page, the RTC battery charger is
   always on now, and wasn't before.  from our conversation
   on IRC, it sounds like the circuit hasn't changed -- is that
   right?  (and that it's less a charge circuit than an
   anti-discharge circuit.)
Bonus points for pointing out an error in the CL1B diagram ---
the RTC battery charger isn't powered outside of suspend and run.

wad

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Re: CL1B power distribution

2009-04-25 Thread John Watlington

On Apr 25, 2009, at 10:09 PM, James Cameron wrote:

 Reviewed the diagram carefully.  The only issue I spotted was that the
 +5VSUS line into the RTC charger comes from a yellow switching voltage
 regulator, despite the RTC charger coloured green.  Either it has to
 come from somewhere else, or the RTC charger has to be yellow, or the
 switching regulator has to be green.  ;-)

This is a mistake in the colouring of the RTC charger block -- it  
should be yellow.

 On the individual USB switching, can this be done between the USB chip
 and the socket?  Being able to switch external devices would have
 significant educational benefit in electronics teaching.  Perhaps only
 switch two of the three, leaving the full capability on one.

Quick straw poll on how many people think it is useful enough have  
individual
control over the power supplied to each connector to raise the cost  
of the laptop
by $0.15 ?

Cheers,
wad
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Re: CL1B power distribution

2009-04-25 Thread Benjamin M. Schwartz
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1

John Watlington wrote:
 Quick straw poll on how many people think it is useful enough have  
 individual
 control over the power supplied to each connector to raise the cost  
 of the laptop
 by $0.15 ?

Turning off a single port to which nothing is connected saves no power,
right?  I don't see the appeal.  Maybe for deactivating power to passive
devices (e.g. usb sticks) during suspend, but such devices are cheap to
power anyway, and may not shut down cleanly if their power supply is
killed.  Moreover, I am persuaded by your argument that the software is
unlikely to get smart enough to use it.

Also, these switches are actually transistors, with some leakage current
and some effective resistance, right?  So it seems like we pay for the
flexibility of these switches with a small increase in power requirements.

- --Ben
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Re: CL1B power distribution

2009-04-25 Thread John Watlington

On Apr 26, 2009, at 12:40 AM, Benjamin M. Schwartz wrote:

 -BEGIN PGP SIGNED MESSAGE-
 Hash: SHA1

 John Watlington wrote:
 Quick straw poll on how many people think it is useful enough have
 individual
 control over the power supplied to each connector to raise the cost
 of the laptop
 by $0.15 ?

 Turning off a single port to which nothing is connected saves no  
 power,
 right?

Correct.

 I don't see the appeal.  Maybe for deactivating power to passive
 devices (e.g. usb sticks) during suspend, but such devices are  
 cheap to
 power anyway, and may not shut down cleanly if their power supply is
 killed.  Moreover, I am persuaded by your argument that the  
 software is
 unlikely to get smart enough to use it.

 Also, these switches are actually transistors, with some leakage  
 current
 and some effective resistance, right?

The leakage current is negligible (sub uA -- especially with nothing  
connected...)

With a little design, you can get effective resistances around 22  
milliohms
for the price I mentioned (OK, maybe $0.18).   This yields a loss of  
6 mW (0.25%)
at full rated power (0.5 A), and 22 mW (0.44%) at our rated power (1A  
through any
connector).

 So it seems like we pay for the flexibility of these switches with  
 a small
 increase in power requirements.

The price is the dominant factor.

wad

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Re: CL1B power distribution

2009-04-24 Thread John Watlington

BTW, Gen 1.5 is the OLPC codename for the next revision of the XO.

The official Quanta model number for the XO was CL1.
The version of the XO with a new touchpad is CL1A.
The Quanta model number for Gen 1.5 is CL1B.

Cheers,
wad

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Re: CL1B power distribution

2009-04-24 Thread Albert Cahalan
John Watlington writes:

 - The SD slot and USB ports may be powered in suspend
  This is just in case some SD cards or USB devices don't handle
 being suspended
  aggressively.   We will support laptop wakeup on interrupt from any
  of these ports (SD or USB).   Under software control they may
 also be powered
  down during suspend.

There is value in making this per-port for the USB.

 - The audio codec remains partially powered in suspend
  This is in order to support wakeup on jack insertion.  The codec
  may be placed in a very low power state during suspend.

I would have expected power to be optional. The software doesn't
always need to use this component during the run state.

 Additional changes from Gen 1 include the ability to both measure
 DC input current and VIN voltage, as well as EC control over the
 current drawn from the DC input. The intent was to better support
 charging directly from solar panels.

I hope that this will be available to activities like Measure.

Ideally updates could be frequent enough to pick up a waveform
from an unrectified power supply. (spare audio channel?)
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