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Re: [Gumstix-users] Verdex USB host on 24pin connector - wait, wiki info is incomplete/inaccurate!
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From: zyagon <zy...@gm...> - 2008-04-08 14:55:24
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i haven't tried it yet, i've to finish first a pcb that is using other signals too and it'll take some time you can try first without them if you want (i wouldn't), it's possible that everything works fine Mike Caruso wrote: > > So, do you have working USB off the 24-pin connector now (using 15k > resistors for both pull down and in series on the data lines plus pulling > USBH_PWR1 to 3.3V)? It's not a hard mod to do, but I'm interested in your > results. > > On Sat, Apr 5, 2008 at 6:32 PM, zyagon <zy...@gm...> wrote: > >> >> it seems only usb host port 2 (60pin hirose) has internal pull-down >> resistors, usb host port 1 (the one on the 24pin connector) does not >> >> >> zyagon wrote: >> > >> > update: >> > >> > check PXA270 Design Guide p.202 here: >> > >> http://pubs.gumstix.com/documents/PXA%20Documentation/PXA270/PXA270%20Design%20Guide%20%5b280001-002%5d.pdf >> > >> > D+ and D- need each: >> > - a 10-25 ohm resistor in series >> > - if pull-down resistors are not software-enabled you need to add them >> > (15K) >> > - ~70pF capacitors >> > >> > i'd add ESD protection too, for example SN65220 single port transient >> > suppressor http://www.ti.com/lit/gpn/sn65220 >> > >> > >> > >> > >> > zyagon wrote: >> >> >> >> USB D+ and D- signals need 15K pull-down resistors, ~30 ohm series >> >> resistors for termination and optionally capacitors for EMI >> suppresion. >> >> Check http://www.fairchildsemi.com/an/AN/AN-5052.pdf (AN-5052 >> >> Implementing the Physical Layer in a USB 2.0 Compliant System) >> >> >> >> As Gordon said in an earlier post (thank you!) here: >> >> http://www.nabble.com/forum/ViewPost.jtp?post=16460889&framed=y >> signals >> >> are passed out directly. The example on the wiki page does not include >> >> those components and signals are not USB compliant (USB devices may >> not >> >> work) >> >> >> >> PXA270 has built in the pull down resistors that can be enabled by >> >> software (i do not know if this has been done for the 24pin connector, >> >> does anyone know?) >> >> >> >> USBHPEN and USBHPWR info is incomplete too, you should use a USB power >> >> switch IC for overcurrent protection, for example TPS2041B >> >> (http://www.ti.com/lit/gpn/tps2041b). In case you do not want to >> >> implement this protection, pull up USBH_PWR1 to 3.3V as explained on >> the >> >> wiki >> >> >> >> >> >> >> >> >> >> >> > >> > >> >> -- >> View this message in context: >> http://www.nabble.com/Verdex-USB-host-on-24pin-connector---wait%2C-wiki-info-is-incomplete-inaccurate%21-tp16500846p16516494.html >> Sent from the Gumstix mailing list archive at Nabble.com. >> >> >> ------------------------------------------------------------------------- >> This SF.net email is sponsored by the 2008 JavaOne(SM) Conference >> Register now and save $200. Hurry, offer ends at 11:59 p.m., >> Monday, April 7! Use priority code J8TLD2. >> >> http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone >> _______________________________________________ >> gumstix-users mailing list >> gum...@li... >> https://lists.sourceforge.net/lists/listinfo/gumstix-users >> > > ------------------------------------------------------------------------- > This SF.net email is sponsored by the 2008 JavaOne(SM) Conference > Register now and save $200. Hurry, offer ends at 11:59 p.m., > Monday, April 7! Use priority code J8TLD2. > http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > -- View this message in context: http://www.nabble.com/Verdex-USB-host-on-24pin-connector---wait%2C-wiki-info-is-incomplete-inaccurate%21-tp16500846p16559147.html Sent from the Gumstix mailing list archive at Nabble.com. |