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Lesson 11: Photoresistor Module

In this lesson, you’ll learn how to connect a photoresistor module to the Raspberry Pi Pico W in order to measure light intensity. By linking the photoresistor to the analog input, you can read different analog values that correspond to varying light levels. This project is ideal for beginners and provides hands-on experience in utilizing analog inputs on the Raspberry Pi Pico W with MicroPython.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
Universal Maker Sensor Kit	94	Universal Maker Sensor Kit

You can also buy them separately from the links below.

Component Introduction	Purchase Link
Raspberry Pi Pico W	BUY
Photoresistor Module	BUY
Breadboard	BUY

Wiring

../_images/Lesson_11_photoresistor_module_bb.png

Code

import machine  # Hardware control library
import time  # Time control library

photoresistor = machine.ADC(26)  # Initialize ADC on pin 26

while True:
    value = photoresistor.read_u16()  # Read analog value
    print(value)  # Print the value

    time.sleep_ms(200)  # Delay of 200 ms between reads

Code Analysis

Importing Libraries:

The code begins by importing necessary libraries. The machine library is used for controlling hardware components, and the time library is used for managing time-related tasks such as delays.
```
import machine  # Hardware control library
import time  # Time control library
```
Initializing the Photoresistor:

Here, we initialize the photoresistor. We use the machine.ADC class to create an ADC object on pin 26, where the photoresistor is connected. The ADC object will be used to read the analog values from the photoresistor.
```
photoresistor = machine.ADC(26)  # Initialize ADC on pin 26
```
Reading from the Photoresistor:

In this loop, the code continuously reads the analog value from the photoresistor using photoresistor.read_u16(). This method reads the value as a 16-bit unsigned integer. The value is then printed to the console.
```
while True:
    value = photoresistor.read_u16()  # Read analog value
    print(value)  # Print the value
```
Adding a Delay:

To prevent the code from running too quickly and flooding the console with data, a delay of 200 milliseconds is introduced after each read using time.sleep_ms(200).
```
time.sleep_ms(200)  # Delay of 200 ms between reads
```