Using IR Chapters 7 & 8 of Robotics with the Boe-Bot.
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Transcript of Using IR Chapters 7 & 8 of Robotics with the Boe-Bot.
Using IR
Chapters 7 & 8 of Robotics with the Boe-Bot
Wireless Communication
Wireless communication: Personal organizers beam data into desktop
computers wireless remotes let us channel surf.
Many remote controls and PDA’s 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
Visible Light Waves
Infrared
The IR Detector
The IR detector is only looking for infrared that’s 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.
Schematics
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 detector’s output in a variable.
FREQOUT 8, 1, 38500irDetectLeft = IN9
The IR detector’s 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 detector’s output only stays low for a fraction of a millisecond after the FREQOUT command is done sending the signal, so it’s essential to store the IR detector’s output in a variable immediately after sending the FREQOUT command.
Simple Display Program
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.
OBJECT DETECTION AND AVOIDANCE
OBJECT DETECTION AND AVOIDANCE
Other Tricks
Drop off detectionSimulating a drop-off with electrical
tape Distance detection Following a stripe Communication