Writing a keyboard device driver

Question

I was wondering if anybody out there has had experience writing keyboard device drivers. I know the basics of how keyboard interrupts work however don't really know the details of everything. Is it difficult? Too difficult for one person?

I ask this because recently I purchased a Apple keyboard and the windows driver doesn't seem to recognize a lot of keys. Also if you know an easier solution to solve this other than writing a driver I would appreciate that as well. (I've already tried SharpKeys, seems like it's a windows driver problem that it can't recognize certain scan codes)

You could try to see if it's possible to use the drivers bundled with BootCamp. — Bruno
– Bruno, Commented Aug 20, 2010 at 2:30

VoidStar · Accepted Answer · 2014-03-09 08:20:23Z

21

Here is what you will need to write the device driver for Windows:

An understanding of the wdf driver framework (KMDF) and its API's (I don't recommend WDM)
- http://msdn.microsoft.com/en-us/windows/hardware/gg463342
- http://msdn.microsoft.com/en-us/windows/hardware/gg463311
A second PC (or Hyper-V) that you can use for kernel debugging. Download WinDbg and then remote debug the second machine. Do not try to write a device driver without a way to debug.
A complete specification of the keyboard's software<->hardware interface. Maybe an expert can somehow infer the interface experimentally, but this could take ages. I think you'd have better luck reverse engineering the driver on the other platform.

If you can find the source for a very similar driver or the driver on another platform this might become doable, otherwise...

If you are interested in device drivers, try starting by writing a software-only driver. It will most likely be just a "toy", but you can do some really neat stuff in the kernel so maybe its worth having a toy driver. You can communicate between a user-mode .exe and your driver with an IOCTL. Maybe eventually you can update it into a software-only keyboard emulating driver, then try to upgrade it into the actual keyboard device driver that you want.

Found a thread about software-only keyboard drivers: http://www.osronline.com/showthread.cfm?link=119885

Maybe this is useful: http://www.osronline.com/ddkx/intinput/i8042ref_9eb6.htm

Update: Hyper-V is available for all Windows 8 users, and should largely eliminate the "second PC" requirement. You can run your driver on a VM and connect the kernel debugger to it.

edited Mar 9, 2014 at 8:20

answered Oct 6, 2011 at 8:47

VoidStar

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1 Comment

Kenny83 Over a year ago

"I think you'd have better luck reverse engineering the driver...". How would I do this for a Huawei MateBook X Pro's keyboard driver? I've always been interested to learn driver programming so I'd like to attempt this as a learning experience, but also to tweak a few things that I don't like about the native driver. Would it be very difficult for someone with intermediate-level C++ knowledge, but no driver or kernel experience whatsoever?

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