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The usual caveats with respect to refresh timing apply to all
suggestions about displaying something on a computer screen.
Think about watching a picture of a TV set on TV. The image seems
to creep and only part of it is displayed at any given time. Eye strain
is caused by looking at slow scanning monitors. Electronic eyes are
even more sensitive to this flashing. Some have a low-pass filter
in them to discard noise. The Micro Scout may or may not have this
ability built in.
I hypothesize a refresh rate of 85 Hz and a long persistancy phoshor
monitor would be the baseline for keeping the screen registering as
white between successive scans.
A more accurate way to do this would be to paint the square every
time the screen refreshes during the verical blanking period. This
is very hardware and OS specific but a generic tool may have already
been created and be floating around the net. Check if source code
exists for those watches and other devices that are able to read
the flashing screen. I would be very interested in knowing the
rate at which the watches were programmed and learning if they are
tied to the vertical refresh rate.
I cannot test any of these theories. I have a laptop with an LCD.
Its refresh characteristics are totally different with a very long
persistancy (1/5 second versus 1/85 second.)
Doug
Ben Jackson wrote:
>
> In lugnet.robotics, Matthew Miller writes:
> > Richard Earley <richard.earley@worldnet.att.net> wrote:
> > > But that requires timing on the part of the computer. A simple display of a
> > > bar code could also be posted to a web page for access by all....
> >
> > Couldn't you use an animated gif?
>
> I just tried this by modifying the PS barcode maker Doug Eaton posted. I made
> one 'bar' and one 'space' as a 256x256 GIF and merged them with gifmerge as
> directed by Doug's PS (plus all space lead-in/lead-out). I played this back at
> various speeds with xanim, and none of them triggered my microscout (with the
> brightness at 100% and the microscout against the screen). With my monitor's
> 60Hz refresh I have to slow it down a bit to make sure the animation speed
> dominates rather than the monitor refresh rate.
>
> VLL from the scout is transmitted much faster than a monitor could (without a
> dedicated driver of some sort). It also only works if the bright red LED is at
> point-blank range to the microscout's input (my LEGO fiber optics haven't
> arrived yet, curses).
>
> If someone could make this work it would be trivial to put up a CGI script that
> let people enter scripts and get back a GIF which would program their
> microscout. I don't think monitor brightness is going to be sufficient,
> though.
>
> --Ben
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