Penpower EZGo writing tablet driver project - help needed

Techies out there…

A little side project of mine, writing a linux driver for this Taiwanese device:

Project status

Device supports windows only out of the box. Hooked it up to a recent linux kernel, can read and parse out hid reports from it, however it uses it’s own proprietary format for the hid report payload. And that payload is weird, the coordinate system seems to be divided up into four quadrants per axis, can’t really make head or tail of it. I was hoping it would be like a touchpad, where you just get x and y coordinates back.

So basically I have gotten nowhere.

Would love to hear from anyone who has experience with these handwriting tools on the hardware or software side.

Cold emails into Penpower have predictably turned up no response.

What’s in it for you, say for example you are a previous employee of Penpower? Bragging rights basically, as we will get our code upstreamed into the kernel. Hope to hear, well, anything really…

Did you try to open it up? Maybe the hardware wiring will give you hints how this thing is set up.
I doubt you will find board schematics online. But maybe you are lucky and some things printed on the boards/components that will give you something to work with.

No I haven’t opened it up yet.

Searches for the vendor/product id have turned up very little by way of datasheets, documentation. The name of the product in the firmware is even borrowed from another unrelated device, that threw me at first of course :slight_smile:.

I can see the bits where the button presses are registered, its just the movement of the stylus, the actual writing action, which produces a bit of a weird payload. Where one would normally expect some sensible coordinate system. All it has to do is tell the software in userspace where the tip is at a point in time. It is actually more simple than a trackpad, as you don’t have to worry about double presses, and two finger presses etc.

I am currently looking at competitor drivers, like wacom, thinking perhaps they may have stolen some ideas from a competitor. They seem to small a company to come up with their own, but who knows…

I have the windows drivers on the device ROM (it has storage to auto load them on Win), but there are so many damn binaries that binwalking them to try glean info about the apis was a little too much to bear, might have to reconsider that … ho hum.