Re: CL1B power distribution
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 -- ( http://cscott.net/ ) ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 signature.asc Description: OpenPGP digital signature ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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. ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 -- ( http://cscott.net/ ) ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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. -- James Cameronmailto:qu...@us.netrek.org http://quozl.netrek.org/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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. ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 =- paul fox, p...@laptop.org ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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. -- James Cameronmailto:qu...@us.netrek.org http://quozl.netrek.org/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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. -- Richard Smith rich...@laptop.org One Laptop Per Child ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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?) paul =- paul fox, p...@laptop.org ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 signature.asc Description: OpenPGP digital signature ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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. -- Richard Smith rich...@laptop.org One Laptop Per Child ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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. -- Richard Smith rich...@laptop.org One Laptop Per Child ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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.) paul =- paul fox, p...@laptop.org ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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. -- James Cameronmailto:qu...@us.netrek.org http://quozl.netrek.org/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
-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 -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.10 (GNU/Linux) iEYEARECAAYFAknz5a4ACgkQUJT6e6HFtqRgTgCdHb+0t19AEY2VaHOaVYVqC6Fs Tr0AmwVwMtgWTTgzEPys2DpPlksdTv32 =pcyb -END PGP SIGNATURE- ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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 ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: CL1B power distribution
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?) ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
