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| The Following User Says Thank You to LurkerN For This Useful Post: | ||
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2007-11-15
, 18:26
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Posts: 2,152 |
Thanked: 1,490 times |
Joined on Jan 2006
@ Czech Republic
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#62
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Originally Posted by muki
No
Hmmm, seems like you are determined to give me a hard time
Originally Posted by muki
Oh I see. So you talk about different thread but you mean the very same thread just few posts above :-) Now that is perfectly clear "of course" :-) Nevermind.
The current thread of course! Specifically post #51.
Originally Posted by muki
I don't know what else to add except repeating information already provided. As already explained the white list is artificial limitation, if removed everything can be connected (including hubs) which is what OTG specification disallows, that's the only purpose why the list is there. Manufacturers are supposed to test everything allowed and disallow the rest so Nokia did precisely that. Once you disable the white list and recompile kernel anything untested by manufacturer can be connected including hubs and will work (if there is a driver).
Never mind, I will seek the information elsewhere.
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2007-11-15
, 19:24
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Posts: 178 |
Thanked: 40 times |
Joined on Aug 2007
@ UK
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#63
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LurkerN and fanoush, thanks for the info. Scratches head, so disabling the white list allows a hub to be connected, got it, but is OTG protocol/s (whatever) still active and, as suggested by the wikipedia info, only *one* device can be connected, even with a hub in between?
fanoush: re double posting, I could explain in excruciating detail how I/we arrived at this point. Suffice it to say that I made the mistake of double posting and compounded it, in retrospect, by the statement "Excuse the repetition from another thread:...", by which I meant that the statement following the ":" is literally (almost, for the pedants) repeated from another thread, which it was. You have read it slightly differently. Lets leave it at that before it becomes a big yawn for all
fanoush: re double posting, I could explain in excruciating detail how I/we arrived at this point. Suffice it to say that I made the mistake of double posting and compounded it, in retrospect, by the statement "Excuse the repetition from another thread:...", by which I meant that the statement following the ":" is literally (almost, for the pedants) repeated from another thread, which it was. You have read it slightly differently. Lets leave it at that before it becomes a big yawn for all
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2007-11-15
, 19:24
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Posts: 3,524 |
Thanked: 2,958 times |
Joined on Oct 2007
@ Delta Quadrant
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#64
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Originally Posted by LurkerN
A well written, thoughtful, and insightful post. Good job!
The Sharp Zaurus C3xxx and C1000 palmtops had USB OTG capability. I successfully used USB keyboards & mice, external HDD & card readers and bluetooth, wifi & ethernet adapters with it. This leads me to believe that it is indeed only a matter of compiling a kernel with the right options. That and finding OTG Micro-A cables/adapters, compiling driver modules and providing sufficient power to devices. Simple, right?
In other words, a special OTG or whitelisted device is not necessarily required to connect to an OTG host. The reason the USB developers group refers to whitelists and limited host capability is because the target is typically your media player with proprietary OS and limited resources. The TI OMAP processors used in the Nokia tablets provides both host & slave capability. The presence of the Micro-AB socket on the n810 means that it is dual-role, as it accepts both A and B plugs. The role an OTG device takes is dependent on what type of USB plug is used. Micro-A is host, Micro-B is slave. If both connected OTG devices have an AB socket, they may renegotiate the host & slave roles on the fly. This last bit is the true power and differentiator of the OTG specification. The rest is all standard USB, same as found on your desktop.
The presence of only a Mini-B socket on the N800 and 700 means they do not conform to USB standards. This may be the reason why Nokia could not provide official support for host mode on these models. However, the capability is still provided by the TI processor As already known, only a hacked cable and kernel support is needed to enable host mode.
The thought of using an inexpensive portable USB keyboard with a retractable cord
, is exciting. Wireless is nice, but not really necssary for this type of task. Plus, there is no need to charge batteries!
}:^)~
YARR!
Capt'n Corrupt
| The Following User Says Thank You to Capt'n Corrupt For This Useful Post: | ||
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2007-11-15
, 19:37
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Posts: 118 |
Thanked: 16 times |
Joined on Sep 2007
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#65
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Originally Posted by Capt'n Corrupt
Yes, well written but you forgot one thing. The Zaurus line had a 150mA limit on the current supplied through the USB port. That was for the official Sharp rom, but various roms could expand or remove that limit. If the Nokia N810 has an unpowered port then USB OTG would be pointless.
A well written, thoughtful, and insightful post. Good job!
The thought of using an inexpensive portable USB keyboard with a retractable cord
, is exciting. Wireless is nice, but not really necssary for this type of task. Plus, there is no need to charge batteries!
}:^)~
YARR!
Capt'n Corrupt
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2007-11-15
, 20:04
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Posts: 474 |
Thanked: 30 times |
Joined on Jan 2006
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#66
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The N800, and almost certainly the N810, use a powered port at or near 150mA.
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2007-11-15
, 20:19
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Posts: 53 |
Thanked: 7 times |
Joined on Nov 2007
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#67
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Originally Posted by muki
A USB hub does not allow the OTG host/slave negotiation protocol to pass. Thus, the roles are determined by the way in which an OTG device is connected to the hub. There are only two proper ways to connect to a hub, both of which are dictated by the type of cable used. Every hub has either one Mini or full-size B port for the host, and multiple A ports for the devices. A host cable cannot plug into an A port, and a slave cable cannot plug into the B port. The USB plugs & ports are keyed so that compliant cables & devices cannot be used in the wrong role. There are non-compliant cables and adapters out there, which IIRC can destroy a device and/or PC if used outside of the odd application for which they were created.
LurkerN and fanoush, thanks for the info. Scratches head, so disabling the white list allows a hub to be connected, got it, but is OTG protocol/s (whatever) still active and, as suggested by the wikipedia info, only *one* device can be connected, even with a hub in between?
Yes, that explanation is confusing when I read it. It is the best I can do for now. But it makes sense if one examines a hub and its connections.
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2007-11-15
, 20:29
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Posts: 333 |
Thanked: 32 times |
Joined on Jul 2007
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#68
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This may help some of you get you head around way to power devices, it's a mod to use a Wireless USB dongle on a GP2x;
Using a battery pack and a USB Hub and magic;
http://wiki.gp2x.org/wiki/WirelessUSBTutorial
Using a battery pack and a USB Hub and magic;
http://wiki.gp2x.org/wiki/WirelessUSBTutorial
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2007-11-15
, 20:41
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Posts: 2,152 |
Thanked: 1,490 times |
Joined on Jan 2006
@ Czech Republic
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#69
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Originally Posted by muki
You can leave the usb chip inside N800 (and 810) in OTG mode where it detects which cable you insert and it switches to correct mode automatically (client or host) and then perhaps can also negotiate mode switch with real OTG device. You can also force the chip to client (peripheral) or host mode if you don't have proper cable. See http://muru.com/linux/n800-usb-host/ for details.
is OTG protocol/s (whatever) still active and, as suggested by the wikipedia info, only *one* device can be connected, even with a hub in between?
When you switch it to host mode, you can attach normal USB devices like keyboard and also powered hub and then attach more devices to it. I have tried with my N800 and it works. I expect it to be same with N810 since both the hardware and the software is same. N810 may have additional advantage of proper connector for attaching also real OTG devices but otherwise it is same and the manual mode should work too.
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| The Following User Says Thank You to fanoush For This Useful Post: | ||
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2007-11-16
, 02:41
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Posts: 53 |
Thanked: 7 times |
Joined on Nov 2007
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#70
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Originally Posted by BOFH
Here is a battery-powered hub which used 4x AAAs: link
This may help some of you get you head around way to power devices, it's a mod to use a Wireless USB dongle on a GP2x;
Using a battery pack and a USB Hub and magic;
<...pics...>
http://wiki.gp2x.org/wiki/WirelessUSBTutorial
However, for maximum portability I'd like to pair a small NIHM or Li-Ion/Polymer battery with this tiny USB hub: link (it is sold under many different brands at various retail stores). Even better would be if somehow a charger IC could be wired up to the battery and hub, communicating with the host via USB itself. The charger IC would ideally give charge/discharge status to the host, allowing it to unmount/disable/power down USB devices depending on battery status and usage. Unfortunately, I have no qualifications to take on this task. Anyone else?
In other words, a special OTG or whitelisted device is not necessarily required to connect to an OTG host. The reason the USB developers group refers to whitelists and limited host capability is because the target is typically your media player with proprietary OS and limited resources. The TI OMAP processors used in the Nokia tablets provides both host & slave capability. The presence of the Micro-AB socket on the n810 means that it is dual-role, as it accepts both A and B plugs. The role an OTG device takes is dependent on what type of USB plug is used. Micro-A is host, Micro-B is slave. If both connected OTG devices have an AB socket, they may renegotiate the host & slave roles on the fly. This last bit is the true power and differentiator of the OTG specification. The rest is all standard USB, same as found on your desktop.
The presence of only a Mini-B socket on the N800 and 700 means they do not conform to USB standards. This may be the reason why Nokia could not provide official support for host mode on these models. However, the capability is still provided by the TI processor As already known, only a hacked cable and kernel support is needed to enable host mode.