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First Lego League in Virginia and DC

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Subject:
From:
Fredrik Nyman <[log in to unmask]>
Reply To:
Fredrik Nyman <[log in to unmask]>
Date:
Tue, 22 Oct 2013 21:55:28 -0400
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text/plain (58 lines)
Katherine,

Did you buy the EV3 through FLL, so that you have the Educational
version of the EV3 software?

If so, I highly recommend that you start that, File -> New Project ->
Experiment, and plug in the EV3.  No need to download/run; as soon as
you do that, it will start showing you what values it's reading from
everything that is plugged into it.

For the color sensor, you'll see that it outputs different numeric
values for different colors.  Using the "test pad" paper that came
with my NXT, dark blue reads as 6, green as 3, red as 5, yellow as 4,
white as 6 and black as 1. Put the EV3 on the area of the field you're
interested in; is it showing the value you expect?

Next, try switching the color sensor between "color" and "reflected
light intensity" -- the latter is what you'll be using if you're
looking for black and white lines on the field.  Values depend a lot
on what kind of surface the sensor is looking at.  On glossy paper, I
get readings around 20 for black areas, 70 for white areas.  On matte
paper, I get readings around 10 for black areas, 50 for white areas.
On the playmat, I get readings around 5 for black areas, 75 for white
areas, so as with most everything FLL, it was clearly designed
purposefully!

One note: My team hasn't had any luck with reliably detecting colors
on the field.  Using "reflected light intensity" to find black and
white lines works really well though.

On Tue, Oct 22, 2013 at 3:00 PM, Molina, Katherine
<[log in to unmask]> wrote:
> Hello all,
>
> I am very new to the EV3 system. I did not use the color sensor with the
> NXTG. Can anyone direct me to a tutorial on how to program the color sensor?
> I'm not clear how it's different from the light sensor. It seems there must
> be a way to tell it to "find blue" rather than a certain reflected light
> intensity.
>
> Thanks so much!
> Kathy Molina
>
> PS Apologies if this topic has been covered already.
>
>
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