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Lesson 07: Infrared Speed Sensor Module

In this lesson, you will learn how to use the Raspberry Pi Pico W to interface with an infrared speed sensor module. By connecting the sensor to GPIO 16, you will detect obstructions in real-time. The program monitors the sensor output, and when an obstruction is detected, it prints “Obstruction detected” to the console. If there’s no obstruction, it prints “Unobstructed.”

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
Infrared Speed Sensor Module	BUY
Breadboard	BUY

Wiring

Code

from machine import Pin
import time

# Set GPIO 16 as an input pin to read the speed sensor
speed_sensor = Pin(16, Pin.IN)

while True:
    if speed_sensor.value() == 1:
        print("Obstruction detected")
    else:
        print("Unobstructed")

    time.sleep(0.1)  # Short delay to reduce CPU usage

Code Analysis

1. Import Libraries:

   This code begins by importing necessary libraries. The machine library is used to interact with the GPIO pins, and the time library is for adding delays in the program.

   from machine import Pin
   import time
   

2. Sensor Configuration:

   The infrared speed sensor is connected to GPIO 16. It’s set as an input, meaning the Pi Pico W will read data from this pin.

   speed_sensor = Pin(16, Pin.IN)
   

3. Main Loop:

   The while True: loop creates an infinite loop. Inside this loop, the program continuously checks the sensor’s value.

   If speed_sensor.value() is 1, it means the sensor detects an obstruction. If it is 0, then there is no obstruction.

   while True:
       if speed_sensor.value() == 1:
           print("Obstruction detected")
       else:
           print("Unobstructed")
   

4. Delay to Reduce CPU Usage:

   A short delay of 0.1 seconds is introduced in each iteration of the loop. This reduces the CPU usage by preventing the loop from running too rapidly.

   time.sleep(0.1)
   

5. More

   If an encoder is mounted on the motor, the rotational speed of the motor can be calculated by counting the number of times an obstruction passes the sensor within a specific period.