27404 Parallax Inc, 27404 Datasheet - Page 103

• Manufacturer Part Number: 27404
• Description: COMPETITION RING FOR SUMOBOT
• Manufacturer: Parallax Inc

Specifications of 27404

• Accessory Type: Hobby and Education
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: SumoBot®
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Figure 3-11 QTI RC-Decay for Different Surfaces
If there is no surface to reflect IR from the QTI's IR LED, the only source of infrared for
the IR transistor's base is the ambient light in the room. That might be a lot of infrared if
sunlight is streaming through the windows, or a little if the blinds are closed and only a
few fluorescent lights are on. That's the case with the 3500
in mind, your values will also vary with the type of surfaces you are using.
Figure 3-12 shows an example of the SumoBot with one QTI over the white tawara line,
and the other QTI over the black sumo ring surface. It also shows an example of what
the Debug Terminal might display under these conditions. The left QTI only reads 66, a
strong indication that the QTI is over a white line. The right sensor reads 1554, which is
typical for a dark surface. These values will vary from one room and sumo ring to the
next, and in an upcoming activity, we'll take a close look at self calibration so that your
SumoBot can automatically adjust to its environment.
Avoiding Interference to the QTI’s –The QTI sensor has a built-in daylight filter that is
adequate for indirect sunlight indoors. However, you should still avoid placing your sumo
ring in direct or bright indirect sunlight. If you find that your sumo-ring’s surface is too
reflective in direct sunlight, causing false QTI readings, move your ring to an indoor shaded
location.
RCTIME
measurement. Keep