Yes, Rev 2.0 has neither polyfuses nor resistors! Read here http://elinux.org/RPi_Hardware under Power back-powering
The voltage with 4.84V is at the rather low end. Definitely try a powered USB-hub first. In your case I would upgrade too, to take advantage of the modifications to the USB communication. Good luck! Martin On 02/17/2013 04:26 PM, Attila wrote: > Thank you - > > I have the latest RasPi which came out with 256MB RAM (I think it is > called Rev2 - with mounting holes on it, altered GPIO, and made in UK). > does this has polyfuses removed from USB? > > I checked voltage between TP1 and TP2 - it says 4.84V > > So what I'll try: > 1. upgrade kernel (now its running on 3.1.9 . Occidentalis 0.2) > 2. Set USB to 1.1 > 3. try a powered hub > 4. try a different USB master > 5. try to disable LAN (it will hurt, I hate wifi) > 6. Try to add the 1ohm resistors > > Why I think its USB power problem? Syslog says: > Feb 16 22:46:22 raspberrypi kernel: [ 3.609129] usb 1-1.2: new full > speed USB device number 5 using dwc_otg > Feb 16 22:46:22 raspberrypi kernel: [ 3.719153] usb 1-1.2: device > descriptor read/64, error -32 > Feb 16 22:46:22 raspberrypi kernel: [ 3.909125] usb 1-1.2: device > descriptor read/64, error -32 > Feb 16 22:46:22 raspberrypi kernel: [ 4.098976] usb 1-1.2: new full > speed USB device number 6 using dwc_otg > Feb 16 22:46:22 raspberrypi kernel: [ 4.538872] usb 1-1.2: device not > accepting address 6, error -32 > > > > Some forum says its power related, but could not find any "official" > description. > > So working on it - thanks for the hints for everyone. > > On Sat, Feb 16, 2013 at 10:45 PM, p4trykx <p4tr...@gmail.com > <mailto:p4tr...@gmail.com>> wrote: > > Hello > > First of all make sure you have the latest kernel run > rpi-update(google how to install it). This is a big improvement in usb > functioning. > I looked at the site and it seems that your adapter is an DS2483 with > some usb serial adapter. This is not a good solution. I personally > does not have any experience with those but I've read people have > problems with usb serial adapters like FT232. > > Second you could also try to force usb 1.1 this should help however > the LAN(it's also on USB bus) performance could be limited. > dwc_otg.speed=1 > > http://raspberrypi.stackexchange.com/questions/1886/what-kernel-parameters-are-available-for-fixing-usb-problems > > > > I doubt it's a power problem. If your power supply is truly 2A. You > can check the voltage on the board TP1 TP2. > Which version of Raspi board do you have? The most recent ones have > usb polyfuses removed so there shouldn't be any significant voltage > drops with good power supply. > I run a power hungry 3G modem directly form little modified first > version of Raspi. 1 ohm resistors added over usb polyfuses and some > extra caps.Here is the thread with modifications > > http://www.raspberrypi.org/phpBB3/viewtopic.php?f=63&t=8591&p=210186#p210186 > > <http://www.raspberrypi.org/phpBB3/viewtopic.php?f=63&t=8591&p=210186#p210186> > I have a "original" power supply from RS Components. > I can even plug and unplug the modem and Raspi does not restart. > Raspi(v2) usb ports are directly connected to 5V rail so when you > connect some device which has ceramic capacitors inside(almost every > device) they start to charge. Those caps can charge very fast so for > fractions it's like a shot circuit. For more detail information you > can read the thread it's explained there why this works. Or ask here I > will try to explain it however I'm not an trained electronic engineer. > > > There where sucess reports of usb 1-wire adapters here but I can't > rememberer exactly which one it was. Perhaps the "native" DS2490. > > > > > -- > p4trykx > > > ------------------------------------------------------------------------------ > The Go Parallel Website, sponsored by Intel - in partnership with > Geeknet, > is your hub for all things parallel software development, from > weekly thought > leadership blogs to news, videos, case studies, tutorials, tech docs, > whitepapers, evaluation guides, and opinion stories. Check out the most > recent posts - join the conversation now. > http://goparallel.sourceforge.net/ > _______________________________________________ > Owfs-developers mailing list > Owfs-developers@lists.sourceforge.net > <mailto:Owfs-developers@lists.sourceforge.net> > https://lists.sourceforge.net/lists/listinfo/owfs-developers > > > > > ------------------------------------------------------------------------------ > The Go Parallel Website, sponsored by Intel - in partnership with Geeknet, > is your hub for all things parallel software development, from weekly thought > leadership blogs to news, videos, case studies, tutorials, tech docs, > whitepapers, evaluation guides, and opinion stories. Check out the most > recent posts - join the conversation now. http://goparallel.sourceforge.net/ > > > > _______________________________________________ > Owfs-developers mailing list > Owfs-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/owfs-developers ------------------------------------------------------------------------------ The Go Parallel Website, sponsored by Intel - in partnership with Geeknet, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials, tech docs, whitepapers, evaluation guides, and opinion stories. Check out the most recent posts - join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
