If you labored with computers back again in the 1970s, there’s a fantastic likelihood you employed a gentle pen at some point: a very simple input unit that you’d point at the CRT display to highlight text, opt for menu choices or manipulate graphic objects. Even though ubiquitous in those times, the gentle pen dropped the struggle for ergonomics to the humble mouse and was all but extinct by the late 1980s. Touchscreen styluses apply a comparable functionality right now, but touching the display screen in some way does not sense the identical as simply pointing at it.
We therefore applaud [Maciej Witkowiak]’s initiatives to deliver the light-weight pen into the 21st century by making a USB interface for a Commodore 64/128 mild pen. At its heart is an Arduino Micro Professional that implements the USB HID protocol to converse with any modern day computer system. It connects to the classic light-weight pen as effectively as to the computer’s analog show sign and makes use of all those to compute the hold off involving the online video synchronization pulses and the mild pen’s output. The sync pulses are extracted from the online video sign by an LM1881, a sync separator chip that will be acquainted to anyone who’s worked with analog video clip signals.
The Arduino calculates the gentle pen’s place primarily based on the calculated timing intervals and studies it to the pc, employing the absolute positioning method which is also utilised by items like drawing pads. [Maciej] demonstrates his process in the movie embedded down below, in which he employs it to operate the menus on an X window system. A excellent success then, even though there’s a person catch: light pens only work on CRT shows, so you will will need to drag one of people major glass beasts out of storage if you want to check out this you.
We’ve highlighted the Commodore gentle pen right before in this odd gaming input gadget. A identical gadget built with a discrete LED matrix is a great illustration of the mild pen’s doing the job principle.
