Human Interface Device

I’ve been studying Human Interface Devices (HID) lately and getting to know their features and benefits. [As an FYI, in an Ultra Mobile PC the most significant HID is the Touch Screen.] So in getting to know HID better I have managed to also understand it, and it appears there are some real benefits that I felt were worth mentioning as they are not entirely obvious:

• Better ink - w/o the HID driver the pen looks like a mouse and data is sampled 30 times second, a HID compliant driver will allow data to be collected at roughly 100 samples per second. To clarify this a little you might consider a HID-less device sort of having a sticky cursor. It tends to sit on, or on top of, wherever you leave it.
• With the HID driver the cursor gets a little spring in its step and tends to float away from an object in a parallel direction. It does not pull away but if you could disect a Touch Screen you could almost picture a cursor floating above Windows (with a HID Driver) and sitting right on top of Windows (without a HID Driver). Whilst this is not like an Electro Magnetic (EM) enabled Tablet PC (with Active Digitizer) - as there is no hover coordinate - it does have some distinct benefits.
• For one the Tablet Input Panel (TIP) tends to float near the text input boxes, and, secondly the cursor will hover over a hyperlink or button without inherently pressing it.
• Another benefit of having a HID Driver on you UMPC is the additional data that is collected by the Touch Controller. The Touchscreen is connected to the Motherboard of a computer via a Touch Controller (and subsequently communicates to the Operating System via a Driver). So if you take into account that an EM Active Digitizer will record pressure sensitivity and cursor jumping. It is hard to imagine this possible on a touchscreen but with a properly installed HID Compliant Driver it is.

Microsoft provides a document for OEMs that stipulates “actual” usages that need to be present in HID. Lets take a look at some of them:

• In an Active Digitizer the HID will communicate X and Y coordinates, Tip switch (pen movements) and In-range (the Hover). As an option (to the OEM) it can also communicate Pressure, Tilt, Invert and receive information from a Barrel button (button on pen).
• In a Touch Screen enabled device the HID will communicate X and Y coordinates, Tip switch (pen movements) and In-range too. The last one, In-range, I guess is the most crucial for us UMPC lovers. It is the piece of information that defines a usable experience, versus a barely tolerable one.

So in writing this post I want to give you some food for thought around why we keep bring HID up all the time. It is one of those acronyms that sounds uberly geekish and absurdly nerd-ish however it is also something that we should demand from our manufacturers. With HID Drivers a UMPC can start to imitate an EM enabled Tablet, without it your pen and touch experience is quite literally stuck! So when I hear about new touch screen devices like The Shift or others, all I am suggesting is that you ask the manufacturer: "to show you the HID Driver?!?!"

For more information on HID go here, or visit here.

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