DIY Light pen- how tosend absolute position & pressure to PC/software?
I have the hardware side of things largely figured out, so I can get an absolute position of the pen on the screen and a pressure value, but I don't know the best way to go about getting those values into the PC or software.
Ideally, I'd like to use R-S232 or PS/2 to connect to the PC, in both of which the cursor could be homed by the hardware and then moved to an absolute position by keeping track of the relative positions sent, all using the standard drivers, albeit without a pressure input. However, I have found this specification for synaptics touchpads, which provides information on using their driver to send more data (including pressure) over the PS/2 or serial connection, but I can't tell if the absolute mode is intended to work as I want it to, or if is simply to catch and correct any bad position reports. I also doubt this pressure input will be recognised or used by any software.
The only alternative I can see is USB, which looks horrible to try and implement, and still doesn't look as though it will support a pressure input with the standard drivers. Ideally I'd like to try to emulate one of wacoms touchscreens, as this would allow me to use their drivers, allowing it to be compatible with most software, though so far I have been unable to find any information on this, and don't expect that I will be able to get it without borrowing a tablet and watching the communications with the PC.
Which interface would be best, and does anyone have any suggestions regarding drivers?
Thanks in advance for any help.