binholmist wrote:Some extra info which might be useful. I have the Linx 7, and the 4-cable OTG dongle of the type on the eBay link and in the OT. Have set both the UEFI BIOS settings as recommended, and those USB devices with the Power Management tab in Device Manager are all set to not turn off. Could not get OTG + charge to happen.
Then I noticed that the detailed advice in the aliexpress link for the universal OTG Hub said that if a Windows tablet was used in OTG-only state it could get stuck in that state, and the solution was to hold down the power button for 10 seconds to force a complete power-off, and on restart with the dongle connected it should be able to do OTG + charge.
I remembered reading somewhere that with the way Windows is installed on tablets (maybe the WIMBOOT configuration?), it doesn't actually turn off fully when you select Power Off, rather it does a sot of fast hibernate, storing a copy of its current state that allows it to restart much quicker than an actual "cold start". So the advice from the aliexpress vendor made sense, in that holding down the power key to force a hardware shutdown, raher than a software one, would force all connections to be re-registered.
So I tried it - I just tried it from the Start screen with nothing else running - held the power key in until the device shut down. I probably wouldn't do that frequently, as it's killing a running system without going through any shutdown. Next time I'll try taking the Power Off option, then after it appears to be off, holding the power button down for 10-15 seconds to see if it has the same effect of turning it completely off.
I connected the OTG hub with the switch in the charge position, a charger connected to the micro-USB socket, and a keyboard connected to one of the USB sockets. I was using a BlackBerry Playbook charger, because they are well known for being able to deliver a high current - between 2.4 and 3 amps if demanded, and I figured that if the Linx needs its 1.5A charger to run and charge, plus a USB hard drive can draw the standard 500mA, then as soon as you plug anything else in, you're going to need in excess of 2A to be sure of charging.
When I restarted the Linx, it took noticably longer than a normal start up. The blue charging light stayed on, but when it got to the PIN code screen, I was able to enter it with the USB keyboard. I opened the desktop and started Windows Explorer so I could see the existing C: drive then plugged in a USB hard drive which promptly came up as an extra drive in Explorer, which I was able to open and navigate. All the time the charging light stayed on, and using the Battery Bar application on the desktop I was able to onfirm tat the battery was drawing a charge.
So it looks like the inconsistent behaviour might be something to do with how "off" the tablet actually was prior to connecting the hub - if it's working from a saved state that didn't include OTG + charge, then it may not be able to enable that capability. Whereas if it's fully powered off, then enumerating all the connections from scratch as it goes through a full start up might be what enables the capability.
More investigation needed, but if this proves repeatable then it might be the answer, at least on the 7. As it's nearly 2am I'm going to stop now and get some sleep....
This was all I had to do in the end.
Firstly I bought this cable: http://www.ebay.co.uk/itm/171725896495
I had tried it before but only had either charging or able to use the USB drive. I have never been into the bios on my Linx 7, nor have I changed any settings. Only installed a few games and apps from the Windows store, Steam, a couple of others, and general usage of browsing and apps.
So before changing the bios or any settings, I thought I would try JUST a full power down. It worked, no settings changed, no bios changes. Started by shutting down normally using the on screen menus, then switched it on again, then before logging in or opening anything, did a hard power down using the power button by holding in as mentioned for 10 seconds or so, ignoring the swipe down message and keeping the button pressed until the screen went black. Set the cable to charge and plugged a Logitech unifying receiver into the cable (for my K400r), cable into Linx 7, then Blackberry Playbook charger into cable, blue light came on straight away. Switched tablet on and waited for it to boot, blue light still on, logged on using keyboard, all good, plugged in USB memory, it installed the driver and was able to access fine, keyboard still being used, blue light still on, desktop showing it as charging. A few minutes have gone by and it has increased from 18% to 19% charge, now up to 23%. So all good and working great.
Now I can look at doing a permanent install in the car, that will be a fun little job to do.