Cheap Lightpen
![Oldbitcollector (Jeff)](https://forums.parallax.com/uploads/userpics/867/nV6URMYKHT1D6.jpg)
I noticed that Radio Shack still had some old fashion Photoresistors so I grabbed a pack.
As it turns out they function nicely as an old-fashion light pen connecting them between IO and 3v with
the IO side pulled down using a 10k resistor. I've got it drawing on the screen. (slowly) in Femto.
A decent object could yield a snazzy lightpen or add a switch and you'd have a light-gun.
OBC
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New to the Propeller?
Getting started with the Protoboard? - Propeller Cookbook 1.4
Updates to the Cookbook are now posted to: Propeller.warrantyvoid.us
Got an SD card? - PropDOS
Need a part? Got spare electronics? - The Electronics Exchange
As it turns out they function nicely as an old-fashion light pen connecting them between IO and 3v with
the IO side pulled down using a 10k resistor. I've got it drawing on the screen. (slowly) in Femto.
A decent object could yield a snazzy lightpen or add a switch and you'd have a light-gun.
OBC
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
New to the Propeller?
Getting started with the Protoboard? - Propeller Cookbook 1.4
Updates to the Cookbook are now posted to: Propeller.warrantyvoid.us
Got an SD card? - PropDOS
Need a part? Got spare electronics? - The Electronics Exchange
Comments
I've thought about doing something like this for quite sometime, but haven't gotten around to doing anything yet... similar to a light pen project I entered into an SX contest.
Only coming from the Propeller itself, it might actually be a lot easier, since you "know" where the vertical and horizontal sync are, or at least you have a better reference to where they are.
What's essential is a good "trigger" circuit on the front end with your photo-transistor. I ended up settling on a basic current mirror design to act as a buffer to the photo-transistor which worked really well... better than just a pull-down resistor. I'll see if I can find a schematic.
I'd be very interested to see a Light Pen object for the Propeller!!!
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
KK
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Propeller + Hardware - extra bits for the bit bucket =· 1 Coffeeless KaosKidd
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Here is the conditioning circuit that I used for a Light-Pen project that provided a nice signal to the SX.
http://forums.parallax.com/attachment.php?attachmentid=40329
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.