Using IR

1
Using IR

• Chapters 7 8 of Robotics with the Boe-Bot

2
Wireless Communication

• Wireless communication
• Personal organizers beam data into desktop
  computers
• wireless remotes let us channel surf.
• Many remote controls and PDAs use signals in the
  infrared frequency range to communicate, below
  the visible light spectrum.
• With a few inexpensive and widely available
  parts, the BASIC Stamp can also receive and
  transmit infrared light signals

3
Visible Light Waves
4
Infrared
5
The IR Detector

• The IR detector is only looking for infrared
  thats flashing on and off 38,500 times per
  second.
• It has built-in optical filters that allow very
  little light except the 980 nm infrared.
• It also has an electronic filter that only allows
  signals around 38.5 kHz to pass through.
• This prevents IR interference from common sources
  such as sunlight and indoor lighting.

6
Schematics
7
Detecting IR

• The key to making each IR LED/detector pair work
  is to send 1 ms of 38.5 kHz FREQOUT, and then,
  immediately store the IR detectors output in a
  variable.
• FREQOUT 8, 1, 38500
• irDetectLeft IN9
• The IR detectors output state when it sees no IR
  signal is high. When the IR detector sees the
  38500 Hz harmonic reflected by an object, its
  output is low.
• The IR detectors output only stays low for a
  fraction of a millisecond after the FREQOUT
  command is done sending the signal, so its
  essential to store the IR detectors output in a
  variable immediately after sending the FREQOUT
  command.

8
Simple Display Program
9
IR Detection Range

• Less series resistance will make an LED glow more
  brightly.
• Brighter IR LEDs can make it possible to detect
  objects that are further away.

10
OBJECT DETECTION AND AVOIDANCE
11
OBJECT DETECTION AND AVOIDANCE
12
Other Tricks

• Drop off detection
• Simulating a drop-off with electrical tape
• Distance detection
• Following a stripe
• Communication