Datasheet

Chapter 7 Navigating with Infrared Headlights
230Robotics with the BOE Shield-Bot
If the source turns out to be sunlight streaming in through a window, close the
blinds and retest, or move your obstacle course to a location that’s well away
from the window.
Always use this IrInterferenceSniffer to make sure that any area where you are using the BOE
Shield-Bot is free of infrared interference.
Activity 3: Detection Range Adjustments
You may have noticed that brighter car headlights (or a brighter flashlight) can be used to
see objects that are further away when it’s dark. By making the BOE Shield-Bot’s infrared
LED headlights brighter, you can also increase its detection range. A smaller resistor allows
more current to flow through an LED. More current through an LED is what causes it to glow
more brightly. In this activity, you will examine the effect of different resistance values with
both the red and infrared LEDs.
Parts List:
You will need some extra parts for this activity:
(2) Resistors, 470 Ω (yellow-violet-brown)
(2) Resistors, 220 Ω (red-red-brown)
(2) Resistors, 1 kΩ (brown-black-red)
(2) Resistors, 4.7 kΩ (yellow-violet-red)
Series Resistance and LED Brightness
First, let’s use one of the red LEDs to see the difference that a resistor makes in how brightly
an LED glows. All we need to test the LED is a sketch that sends a high signal to the LED.
Example Sketch P1LedHigh
Create, save, and run the sketch LeftLedOn.
Run the sketch and verify that the LED in the circuit connected to P8 emits light.