70009 Parallax Inc, 70009 Datasheet - Page 90

• Manufacturer Part Number: 70009
• Description: BOOK UNDERSTANDING SIGNALS
• Manufacturer: Parallax Inc
• Type: Signal Analysisr

Specifications of 70009

• Style: Book
• Title: Understanding Signals
• Contents: Guide to Generate, View and Measure Wave Forms
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Other names: 70009PAR

Another use for IR is object detection (Figure 7-2). The IR beam reflects off objects just
like light. When an IR beam is transmitted out, you can use the detector to look for an
echo or reflection.
When you transmit a burst of IR light, if there is an object close enough the IR light will
reflect that light back. The detector will see the light and pull its output pin low.
You can even tell how far away the object is by changing the sensitivity of the detector.
By scanning at slightly different frequencies you can determine how far from an object is
from the detector. For more information on distance detection see the article and
application note references in the Further Investigation section at the end of this chapter.
ACTIVITY #1: INFRARED SIGNALS FOR OBJECT DETECTION
In this activity we will use the BASIC Stamp to generate the 38 kHz signal required to
make the infrared detector’s output go “low”.
Required Parts
(1) 220 Ω resistor
(1) Infrared detector
(1) Infrared LED
(8) Jumper wires
Object
Object
Figure 7-2:
Infrared for object
detection