shenson | # 321 | 2008-01-23, 19:00 | Report

For those in the UK I tried an adaptor on eBay from psylins described as a USB A Female to 5 Pin Mini B Plug Gender Changer. This does not auto switch to host mode but works fine when manually switched.

I tried it on a cheap Poundland USB card reader and it worked fine.

lutchann | # 322 | 2008-01-23, 22:45 | Report

Hi all,

I'm successfully using my N800 in USB host mode with the GoldX cable kit that was mentioned in the N810 thread. (No auto-switching with this cable, either.) I picked up a cheap powered hub based on the Genesys Logic GL850A chip, which seems to work fine, and is cute as a button to boot.

The biggest problem with the hub, though, is that although it can operate in bus-powered or self-powered mode, it always reports to the host that the AC wall adapter is attached. This seems a bit dangerous--if the user connects four current-hungry devices without supplying external power, I don't see what would prevent the hub from attempting to suck 2+ amps out of the upstream port. I don't intend to ever use this device in bus-powered mode, so I'm not too upset, but I'm a little concerned about inadvertently disconnecting the AC power during heavy current draw. I could see this happening if I accidentally plug into a switched outlet in a hotel room, for example.

So, my question is--does the N800 have any sort of over-current protection? Would it damage the device to suddenly attempt to draw an amp or so from the onboard USB port?

hostman | # 323 | 2008-01-23, 23:31 | Report

The N800 will just shut off the 100mA-limited supply and stop working in host mode. You'll need to reboot to fix it. Nothing will be permanently damaged.

-Robert

lutchann | # 324 | 2008-01-24, 00:24 | Report

Great, thanks Robert. After reading your post, I gave it a try myself, and confirmed that an excessive current condition simply causes the musb device to shut down with a lot of vbus errors in dmesg. A reboot of the N800 restores everything to working again.

I should also share a hint about recharging devices like cell phones from a powered USB hub connected to an N800. By default, USB auto-suspend is enabled in OS2008, which causes client devices to be put into suspend mode after two seconds of no activity. Suspend mode is supposed to be low power mode, so most devices won't recharge when suspended. To disable this, change the autosuspend parameter of the usbcore module:

echo 400000 >/sys/module/usbcore/parameters/autosuspend

This changes the autosuspend timeout to 400,000 seconds. This needs to be done before any USB devices are connected.

Keep in mind that disabling auto-suspend will impact your battery life, though, so only disable it when your N800 is connected to AC power! (Or, in my case, a CA-100 cable looped back into the powered hub...)

jolouis | # 325 | 2008-01-24, 03:25 | Report

For all those looking for auto-switching USB on the N800; how much interest is there in being able to purchase a "professionally modified" N800 to Female USB cable? I described my process previously about bending up the metal casing, adding a touch of solder, and heat-shrinking a USB gender-changer to make a nice clean auto-switching cable on a budget, but I know there were a few responses saying things along the lines of "'Easy' is relative if you don't have a soldering iron". If there's interest I'd be happy to mod up some of these cables and put 'em up for sale on my company's e-store for relatively cheap (a few bucks more than the cost of the cable itself and adapter). I'd also consider just splicing some cables together instead of using the gender changer, but I think in the end the gender changer with heat-shrink actually makes for a cleaner cable with better connections (since there aren't any wires that actually ahve to be spliced... those USB wires are tiny after all!).
We're based in Canada so anything beyond North American shipping costs might be a bit silly for just a cable, but I'd have to look into it.

Anyways, Yays or Nays?

-Rob

nhanquy | # 326 | 2008-01-24, 03:59 | Report

Yays Yays Yays Yays Yays

raynman | # 327 | 2008-01-24, 04:15 | Report

Rob, I have interest in that idea. One ideal cable for me would be something that stays close to the outer edge of the N800. Ideas: an L-connector on one end (or a "knuckle"); a flat cable; about 3" long (to end up at the middle of the bottom of the N800). Then, if I needed a peripheral to stay with the N800, I could dream up some way to attach it to the back.

Whadaya think?

jolouis | # 328 | 2008-01-24, 04:32 | Report

Probably the most viable solution out of those for that sort of approach would be something like a short 3-4" long "dongle" type of cable that could connect into the USB on the N800 and then wrap around to the back. One thing to keep in mind of course is that the USB port is only exposed when the kick-stand is lifted up, so unless you plan on permantenly removing your stand having a USB device connected while carrying the tablet around in your hand is not exactly ideal.

The "dongle" type of cable is the only one that would be fairly easy to mod up as a flat cable or "L-style" would require some plastic fab work that I'm really not up to at this point. (It's possible but I can't think of a way to do it that wouldn't put a lot of stress on the USB connectors themselves when connecting/disconnecting, so a cable is a better and easier approach).

Thoughts/responses to that? In the mean time I'll source out some parts tomorrow or Friday for a "standard" cable as I mentioned originally, so keep an eye on the forum here and I'll post up a link in the next few days.

-Rob

raynman | # 329 | 2008-01-24, 05:30 | Report

Rob, I can't disagree with your preference of using a dongle type cable to begin with. Maybe someone with more cable-modding experience could offer some advice there.

You're right about the kickstand issue-- I was aware of that. I still think people could be interested in walking around with something attached and that the kickstand is just something we'd have to put up with. I could be wrong, though.

I'm eager to see what you come up with! I'm new here, but I would suggest opening a new thread for the purpose of surveying interest in purchasing your modded cables and, if it comes to this, marketing them.

mplawner | # 330 | 2008-01-24, 06:28 | Report

Yup! Sorry about that! I've fixed the post.