Re: Ambient light sensing via LED response
But why do you say you would need 1 mV accuracy ? Bright sunlight is far stronger than the light sources he used. I am not an engineer so forgive me if I am saying something stupid, but is not the goal to switch off the backlight if and only if there is no difference between the switched on and switched off state? I mean that this implies that you have to measure the mV at a light level when you cannot see the difference (what can be a much fainter light than the sun). ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Creating a Puritan Howto for Ubuntu (8.10)
Dear All, After surveying the tools that we have available for creating custom OLPC builds which seems to be a menu of NAND Customizer, Pilgrim, or Puritan Puritan looks like being the way forward for us as we have not yet invested much time / effort in other tools (we run a shell script customizer on the first laptops we put out), Puritan seems to have better support for Ubuntu (when we tried Pilgrim before we gave up on Ubuntu, ran it in a Fedora VM, then on our bandwidth had to run on a Fedora VM on a remote server in Germany), and the principles behind it look like meeting the challenges we face. What I really like is caching - that is unbelievably important. Squid does not do a good job of caching repos etc. and the only way before we did that was running Polipo to cache every single HTTP request mindlessly. 1. On applying the patch to mock - Not quite sure how that is done here as the mock package through apt is compiled in binary. We tried apt-get source mock and then grep for the strings which are in the patch; but it has: PKGPYTHONDIR = os.path.join(os.path.dirname(os.path.realpath(sys.argv[0])), mock) not PKGPYTHONDIR=/var/lib/python-support/python2.4/mock (as specified by the patch referenced at http://wiki.laptop.org/go/Puritan - Ubuntu section Which makes mock.patch fail. What is the recommended way of dealing with this? Can we make an official debian format patch for this package or maybe setup a PPA? 2. Are there any specific instructions for ensuring that caching is enabled? Couldn't find that on the wiki at the moment... 3. I would like to make a more step by step kind of Wiki page for new deployments such as ourselves here in Afghanistan - I have started at http://wiki.laptop.org/go/Puritan/StepByStep - hopefully we can go through the whole thing tested against a regular Ubuntu 8.10 install so that we have something for deployments to quickly and easilyget going with making custom images. Thanks, -Mike ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Battery recovery issues
Here's the logfile. Just one observation: it tooked me 3:30 h to discharge the battery (I did a bat-recover for 16 hours previously), so the battery seems to be in good shape, and also the XO, since with other batteries the led and output from all these commands behave as expected. Also, I want you to know that the first 20 batteries I tested weren't faulty, they just needed to be charged (trickle charged at the begining, then normal charged). I think that kids and our technicians don't know what does the 4-times-blinking-orange-led mean, so I'm giving them immediate instructions on how to proceed. On Tue, May 5, 2009 at 6:44 PM, Richard A. Smith rich...@laptop.org wrote: Emiliano Pastorino wrote: bat-charge reports this: 320.83 mAh (7d53) 1428.12 mA (2ddc) 6.492 V (195c) Chg: 0.41mAh ( 29) then every column raises line to line (I copied that by hand because bat-charge-log always says Can't open file, even when usb stick is plugged in. Turns out the way I did the disk devices won't work unless you either: 1) boot with a usb drive plugged in 2) run 'p2' before bat-debug-log 'p2' will re-probe usb devices. If the first column is battery's charge, then it's almost dry. Should I try bat-recover or charge it the usual way? The first column is the ACR reading and you can't tell anything by just 1 reading. You have to know what it was when you started discharging or charging. I don't report SOC in that listing cause generally I don't care. I want to know what it does after I turn on charge rather than what level it was at previously. bat-charge simply enables charging and then starts reading the battery directly. Thus it does not care about any of the settings in the EEPROM. Its a good diag tool to see if the battery just physically won't take charge or if you just can't communicate to it at all. If bat-charge works but normal charging does not then its EC or EEPROM badness. The LFP batteries have an overvoltage cutoff that will protect them so its ok to just turn one on and leave it. For NiMH you would end up reducing its life. But since you don't have any NiMH you don't care. 'bat-recover' works by PWMing the charge pin to keep the charge current very low and allow the cells to equalize yet not trip the over voltage like they would if you just turned on the charge and left it. The settings I've picked by default seem to work in most cases but I've had many batteries where I needed to reduce the current even further from the default settings. To speed up the process you can use normal charging methods to get the battery close to full (or wherever it cuts out at) That way the recover process will be much shorter. I'll try bat-recover with a bunch of batteries today, so maybe tomorrow or on Wednesday I'll be sending you some logs, if it is ok to you. After looking at your bat-debug log I've realize that the extra diagnostic info is only present in f-series firmwares with my newer EC code. I'm forwarding you an e-mail with a copy of q2f02 that I worked on while trying to solve some problems with batteries in another deployment. q2f02 will be behind q2e41 in terms of OFW but has EC code with extra battery diag info. For battery testing there should no difference between the 2. Its also available here: (Just never announced since a new e-series release happened right after) http://dev.laptop.org/pub/firmware/q2f02/ So install f02 on your test laptop and re-run bat-debug-log after you have first run 'p2' and the logging to disk should work. I don't need any more see-bstate info. so the steps: install f02 remove battery boot stop at ok insert usb drive (or boot with it inserted) run 'p2' run 'bat-debug-log' insert battery run for a couple of minutes then hit a key send me the log. I'll try to get a f03 out soon with the latest of everything but I've got gen 1.5 bring up tasks that I need to attend to. -- Richard Smith rich...@laptop.org One Laptop Per Child -- Ing. Emiliano Pastorino LATU - Plan Ceibal Av. Italia 6201 CP: 11500, Montevideo, Uruguay Tel: (598 2) 601 5773 int.: 213 2:29 0 0x0 0x0 0x1 0x1 0x0 0x0 0x0 0x0 0x0 0.00 0.000 0.00 0.00 0 0x0 0x0 2:29 0 0x0 0x0 0x0 0x1 0x0 0x0 0x0 0x0 0x0 0.00 0.000 0.00 0.00 0 0x0 0x0 2:30 0 0x0 0x0 0x0 0x1 0x0 0x0 0x0 0x0 0x0 0.00 0.000 0.00 0.00 0 0x0 0x0 2:30 0 0x0 0x0 0x0 0x1 0x0 0x0 0x0 0x0 0x0 0.00 0.000 0.00 0.00 0 0x0 0x0 2:31 0 0x0 0x0 0x1 0x1 0x0 0x0 0x0 0x0 0x0 0.00 0.000 0.00 0.00 0 0x0 0x0 2:31 0 0x0 0x0 0x1 0x1 0x0 0x0 0x0 0x0 0x0 0.00 0.000 0.00 0.00 0 0x0 0x0 2:32 0 0x0 0x0 0x0 0x1 0x0 0x0 0x0 0x0 0x0 0.00 0.000 0.00 0.00 0 0x0 0x0 2:33 0 0x0 0x0 0x0 0x1 0x0 0x0 0x0 0x0 0x0 0.00 0.000 0.00 0.00 0 0x0 0x0 2:33 0 0x0 0x0 0x1 0x1 0x0 0x0 0x0 0x0 0x0 0.00 0.000 0.00 0.00 0 0x0 0x0 2:34 0 0x0 0x0 0x1 0x1 0x0 0x0 0x0 0x0 0x0 0.00 0.000 0.00 0.00 0 0x0 0x0 2:34 0 0x0 0x0 0x0 0x1 0x0 0x0 0x0 0x0 0x0 0.00 0.000 0.00 0.00 0 0x0 0x0 2:35 0 0x0
Re: [Server-devel] backup : problem opening /library/users/XXXX/datastore-xxxxx/store
On Tue, May 5, 2009 at 4:52 PM, Martin Langhoff martin.langh...@gmail.com wrote: Let's keep this on the list. Is that from a recent SoaS? The datastore storage format has changed then, and we need to add support to Moodle for it. More work! :-p Done - not tested much -- the zipfile you've given me didn't have much data. http://dev.laptop.org/git/users/martin/moodle.git/commit/?h=mdl19-xsid=5f522dbef1878284d15ae2ef0872c8dd5caa1953 So I need your help in reporting whether it works well for your SoaS clients. I assume you're already using my moodle branch, so a mere git pull will get you the right code... ;-) Note: It won't list metadata-only entries. If there's no 'data' file, it's not listed. cheers, m -- martin.langh...@gmail.com mar...@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff ___ Server-devel mailing list server-de...@lists.laptop.org http://lists.laptop.org/listinfo/server-devel
Re: plz test Build 802 + Firmware Q2E41 = Candidate Release 8.2.1
On Thu, Apr 30, 2009 at 5:41 AM, Holt h...@laptop.org wrote: The build is now signed so you don't even need a developer key: http://wiki.laptop.org/go/Friends_in_testing Helping us test WPA (WPA2 especially) would be most useful, since these wifi connections sometimes fail as much as 20% of the time, when Release 8.2.0 seemed to fail only ~10% of the time. And of course try: http://wiki.laptop.org/go/1_hour_smoke_test Please help us clean up Release Notes on the way! http://wiki.laptop.org/go/Release_notes/8.2.1 Recap -- all you should need are these 2 files burned onto a USB stick: http://download.laptop.org/xo-1/os/candidate/802/jffs2/os802.img (233MB) http://download.laptop.org/xo-1/os/candidate/802/jffs2/fs.zip (155K) Follow the usual procedure (http://wiki.laptop.org/go/USB_update), grab Activities from your XO's Control Panel later, and Buzz (IRC Live Chat) if you get stuck: http://forum.laptop.org/chat Thanks! In case it is useful, I used 802 on a B4 and a MP to develop and test file sharing for the ImageViewer activity and FBReader activity. Did not see any problems. (I was connected over a unsecured Linksys WRT600N AP (with MAC filtering)). Thanks, Sayamindu -- Sayamindu Dasgupta [http://sayamindu.randomink.org/ramblings] ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Battery recovery issues
Emiliano Pastorino wrote: Also, I want you to know that the first 20 batteries I tested weren't faulty, they just needed to be charged (trickle charged at the begining, then normal charged). I think that kids and our technicians don't know what does the 4-times-blinking-orange-led mean, so I'm giving them immediate instructions on how to proceed. It means its in trickle charge but that only happens with newer firmware. -- Richard Smith rich...@laptop.org One Laptop Per Child ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
[Fwd: Re: Ambient light sensing via LED response]
Original Message Subject: Re: Ambient light sensing via LED response Date: Thu, 07 May 2009 00:02:49 +0200 From: Reinder de Haan r...@mveas.com To: raf...@laptop.org References: 200904290017.n3t0hl2v006...@new.toad.com c5d4a4e5-b183-4b7d-bafb-3488e15f7...@laptop.org c6d9bea0905011128j2d5cdf3cw975cfad790480...@mail.gmail.com 675d3c5c-95ed-4ee9-84bc-3b5164675...@laptop.org c6d9bea0905042207i458ed9b1if74e0e16d24f5...@mail.gmail.com 4a00a073.8020...@mveas.com a80d16920905051544s525b7039nf7e87a4a3c754...@mail.gmail.com 75dc0458-925b-4792-9aee-a24b9b1f3...@laptop.org a80d16920905051952h3d82d15brb8f690cf1c402...@mail.gmail.com Rafael Enrique Ortiz Guerrero wrote: On Tue, May 5, 2009 at 8:34 PM, John Watlington w...@laptop.org mailto:w...@laptop.org wrote: On May 5, 2009, at 6:44 PM, Rafael Enrique Ortiz Guerrero wrote: These measurements are really cool. But the question remains in whether the ADC could have a resolution of 1mv?, i mean in light of these measurements is necessary to have an ADC that can reliable sense these variations and then with that basis have a transfer function and add it to the algorithm. Absolutely not. The A/D is eight bits, with an input range spanning 0 - 3.3V, so the best you can hope for is about 13 mV per LSB. I would guess actual accuracy to be closer to 26 mV. But why do you say you would need 1 mV accuracy ? Bright sunlight is far stronger than the light sources he used. i don't know if the measurements at sunlight would show the same variations.. we would have to make new measurements, but for experience, the variations of voltage regarding light sensing are not of considerable amounts, so if the accuracy is 26mv, we would have to see if a perceptible change in ambient light could be of a higher magnitude than 26mv, if not the accuracy could be lost.. i did some more experiments and at ~20 cm from the halogen lamp i doest matter is i turn the backlight full on of off .. i dont have color anymore at that distance the bare led gave about 250mv (maybe a bit more into a very high R fet gate...) i guess it would be around 70mv whit the light guide in front of it.. (i guess this be more (150mv?) with a very high R (~25 Mohm?) fet gate as only load) i would add a simple amp (mosfet? or maybe cheap opamp ?) to amplify ~X10 so 300mv would be full scale.. my memory is dusty but that should be posible with 2 resistors an a fet ? gain would be posible to change by replacing one of the resistors with a bigger / lower value... maybe a trasistor is better bc the leds is acts as a current source ? ideas welcome if i can get the partnr of a fet/transistor that would be usable (and cheap enough) i could maybe order a couple of them from say farnell and hack something together here is there a free or hackable input on the current EC ? (or is that different from the ec that will be in 1.5 ? (haven't checked the specs though..) Having the data sheet for the EC controller doesn't help --- 8 bits and recommended operating voltage for the analog reference voltage is about all it provides. I had to ask a chinese speaker to call the app. engineer to find out the input impedance... Ok, thanks :). On Tue, May 5, 2009 at 3:24 PM, Reinder de Haan r...@mveas.com mailto:r...@mveas.com wrote: Hallo, C. Scott Ananian wrote: snip A last resort would be hooking up a MOSFET as a simple amplifier -- again, you're not worried about linearity or any such niceties, but you'd still need a good match for your MOSFET's threshold voltage... some real measurements to replace the WAGes would go a long way. --scott measured on a B1 XO1 laptop (where the leds and the series resistor are wired in parallel it seam) : almost dark: 0mv ~3meter away from a 8w PL; bare led: ~2mv ~50 cm below ~25W halogen desk lamp; bare led: ~40mv bright white led directly on bare led ~200mv bright white led directly on light guide of the bat.led (lcd side) ~50mv ~50 cm below ~25w halogen desk lamp (~75* angle to the axis of the light guide) ~5mv i measure this between GND of the laptop the led side of the series resistor. all leds seam to be about the same.. i did not compare the different light guides. the main battery and DC power where removed, the RTC baterry was still in place. the meter i measured this with was fixed in the 2000mv range and was abou 10Mohm when i connected it to another meter in resistance mode; the (volt) meter read 250mv at that time.
[Fwd: Re: Ambient light sensing via LED response]
Original Message Subject: Re: Ambient light sensing via LED response Date: Thu, 07 May 2009 00:02:49 +0200 From: Reinder de Haan r...@mveas.com To: raf...@laptop.org References: 200904290017.n3t0hl2v006...@new.toad.com c5d4a4e5-b183-4b7d-bafb-3488e15f7...@laptop.org c6d9bea0905011128j2d5cdf3cw975cfad790480...@mail.gmail.com 675d3c5c-95ed-4ee9-84bc-3b5164675...@laptop.org c6d9bea0905042207i458ed9b1if74e0e16d24f5...@mail.gmail.com 4a00a073.8020...@mveas.com a80d16920905051544s525b7039nf7e87a4a3c754...@mail.gmail.com 75dc0458-925b-4792-9aee-a24b9b1f3...@laptop.org a80d16920905051952h3d82d15brb8f690cf1c402...@mail.gmail.com Rafael Enrique Ortiz Guerrero wrote: On Tue, May 5, 2009 at 8:34 PM, John Watlington w...@laptop.org mailto:w...@laptop.org wrote: On May 5, 2009, at 6:44 PM, Rafael Enrique Ortiz Guerrero wrote: These measurements are really cool. But the question remains in whether the ADC could have a resolution of 1mv?, i mean in light of these measurements is necessary to have an ADC that can reliable sense these variations and then with that basis have a transfer function and add it to the algorithm. Absolutely not. The A/D is eight bits, with an input range spanning 0 - 3.3V, so the best you can hope for is about 13 mV per LSB. I would guess actual accuracy to be closer to 26 mV. But why do you say you would need 1 mV accuracy ? Bright sunlight is far stronger than the light sources he used. i don't know if the measurements at sunlight would show the same variations.. we would have to make new measurements, but for experience, the variations of voltage regarding light sensing are not of considerable amounts, so if the accuracy is 26mv, we would have to see if a perceptible change in ambient light could be of a higher magnitude than 26mv, if not the accuracy could be lost.. i did some more experiments and at ~20 cm from the halogen lamp i doest matter is i turn the backlight full on of off .. i dont have color anymore at that distance the bare led gave about 250mv (maybe a bit more into a very high R fet gate...) i guess it would be around 70mv whit the light guide in front of it.. (i guess this be more (150mv?) with a very high R (~25 Mohm?) fet gate as only load) i would add a simple amp (mosfet? or maybe cheap opamp ?) to amplify ~X10 so 300mv would be full scale.. my memory is dusty but that should be posible with 2 resistors an a fet ? gain would be posible to change by replacing one of the resistors with a bigger / lower value... maybe a trasistor is better bc the leds is acts as a current source ? ideas welcome if i can get the partnr of a fet/transistor that would be usable (and cheap enough) i could maybe order a couple of them from say farnell and hack something together here is there a free or hackable input on the current EC ? (or is that different from the ec that will be in 1.5 ? (haven't checked the specs though..) Having the data sheet for the EC controller doesn't help --- 8 bits and recommended operating voltage for the analog reference voltage is about all it provides. I had to ask a chinese speaker to call the app. engineer to find out the input impedance... Ok, thanks :). On Tue, May 5, 2009 at 3:24 PM, Reinder de Haan r...@mveas.com mailto:r...@mveas.com wrote: Hallo, C. Scott Ananian wrote: snip A last resort would be hooking up a MOSFET as a simple amplifier -- again, you're not worried about linearity or any such niceties, but you'd still need a good match for your MOSFET's threshold voltage... some real measurements to replace the WAGes would go a long way. --scott measured on a B1 XO1 laptop (where the leds and the series resistor are wired in parallel it seam) : almost dark: 0mv ~3meter away from a 8w PL; bare led: ~2mv ~50 cm below ~25W halogen desk lamp; bare led: ~40mv bright white led directly on bare led ~200mv bright white led directly on light guide of the bat.led (lcd side) ~50mv ~50 cm below ~25w halogen desk lamp (~75* angle to the axis of the light guide) ~5mv i measure this between GND of the laptop the led side of the series resistor. all leds seam to be about the same.. i did not compare the different light guides. the main battery and DC power where removed, the RTC baterry was still in place. the meter i measured this with was fixed in the 2000mv range and was abou 10Mohm when i connected it to another meter in resistance mode; the (volt) meter read 250mv at that time.
Re: [Server-devel] backup : problem opening /library/users/XXXX/datastore-xxxxx/store
Martin, Thanks, sorry I don't have a lot of activities to backup yet on my test SoaS. I'll give this a go today and report back the results here. Best, Hamilton On Wed, 2009-05-06 at 19:23 +0200, Martin Langhoff wrote: On Tue, May 5, 2009 at 4:52 PM, Martin Langhoff martin.langh...@gmail.com wrote: Let's keep this on the list. Is that from a recent SoaS? The datastore storage format has changed then, and we need to add support to Moodle for it. More work! :-p Done - not tested much -- the zipfile you've given me didn't have much data. http://dev.laptop.org/git/users/martin/moodle.git/commit/?h=mdl19-xsid=5f522dbef1878284d15ae2ef0872c8dd5caa1953 So I need your help in reporting whether it works well for your SoaS clients. I assume you're already using my moodle branch, so a mere git pull will get you the right code... ;-) Note: It won't list metadata-only entries. If there's no 'data' file, it's not listed. cheers, m signature.asc Description: This is a digitally signed message part ___ Server-devel mailing list Server-devel@lists.laptop.org http://lists.laptop.org/listinfo/server-devel
