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
-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 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
On Apr 25, 2009, at 11:04 AM, Nate Ridderman wrote: > 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. Doesn't hurt to ask, but Quanta still refuses to release these publicly. The schematics for CL1 have been made available under NDA to large purchasers, so that they can run their repair programs. wad ___ 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
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
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
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 One Laptop Per Child ___ 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 One Laptop Per Child ___ 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, 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
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 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
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
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
>>> 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 One Laptop Per Child ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: 3D engine uses in a no-nonsense GUI (was: XO Gen 1.5)
Hal Murray writes: > I've always thought of "slide into view" as annoying. I have to > wait around for the thing I want to look at to finish dancing. Me too, which is why I specified "fast" and "rapid". Animations commonly suffer from various problems: a. You really do have to wait, because the software is terribly slow, and the animation was put there to distract you. b. The animation itself has bad performance. This is where the 3D engine can make a huge difference. c. The animation is purposely slow because the UI designer fell in love with it and he wants you to love it too. You're supposed to sit there and marvel at what a wonderful animation it is. Sometimes multiple reasons apply. Sugar activities take way too long to start if they are written in Python, so we got a throbbing icon for activity startup. This itself is so slow that non-Python activities became much slower. (including Tux Paint, which is NOT lightweight) A decent rule of thumb: if you have time to really focus on the animation, then it is too slow. You should barely even see it as it runs. It should only be there to direct your vision a bit, giving you a feel for where things went or came from. Without a 3D engine, it's not reasonable to expect such performance. ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
