2.6 Light Intensity Display

In this project, we use a photoresistor and the LED Bar Graph to make a light intensity display, where the stronger the light is the more the number of the LED Bar Graph lights up.

Component List

  • Raspberry Pi Pico W x1

  • MicroUSB cable x1

  • 830 Tie-Points Breadboard x1

  • Photoresistor x1

  • LED Bar Graph x1

  • Photoresistor x1

  • Resistor 220Ω x10

  • Resistor 10KΩ x1

  • Jumper Wire Several

Circuit Assembly

../_images/Light_Intensity_Wiring.png

  • The photoresistor interfaces with analog input pin GP26.

  • LED bar graph elements connect to digital output pins GP13 through GP22.

Programming Implementation

Note

  • Utilize the visual programming interface shown below through drag-and-drop methodology.

  • Import 2.6_Light_Intensity_Display.png from the location Ultimate-Starter-Kit-for-Pico-W\Piper_Make. For complete instructions, reference Loading Existing Projects.

../_images/Light_Intensity_Code1.png

Following Pico W connection, activate the Start button to initiate program execution. Obstruct the photoresistor with your hand to observe corresponding changes in the LED bar graph illumination pattern.

How it Works?

../_images/Light_Intensity_Code2.png

Set the pins of LED Bar Graph connected to GP6 ~ GP15.

../_images/Light_Intensity_Code3.png

Store the voltage value of A0 (GP26) read into the variable [photo_vol]. Use the [map value () from () to ()] block to map the variable [photo_vol] from 0 to 3.3V to 0 to 10 (the number of LEDs on the LED Bar Graph).

  • [map value () from () to ()]: map a value from one range to another.