GP32 GP32 Mouse....


AlexW posted on Dec 4 2003 at 07:31 PM said:
Well... Maybe somebody came up with this idé in this or another thread but I remeber when I made a DIY "lightpen" on my C64 a loong time ago... it was one light diode and one transistor and a resistor (if I remember correctly). Very easy to do... it registered the scanline witch a TV/Computer makes... could this be done with a LCD? or is it that LCD does not emit anything at all... hmm... that is probably it... OK... if you could some thing that registers on a lightdiode than you could use the JTAG interface to connect it maybe?
You could have a light right by the sensor, so the sensor would detect the color... Only problem is that theres something about the LCD refresh rate not fast enough to do that...
 
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LCDs do not refresh in the same way that CRTs do. This is why you cannot use light-guns of LCD TVs. They display the image all at once, instead of scanning down the screen. This is because there are no phosphers (spelling?) In the LCD screen to continue to emit light after the pixel has been activated.
 
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