Photo Interrupter

Photo Interrupter

A MicroPython code example running on a Raspberry Pi Pico 2 W microcontroller connected to a photo interrupter module, an RGB LED module and an OLED display module (SSD1306) on a breadboard to increment the count on the display each time the photo interrupter light beam is interrupted

A photo interrupter module sends infrared light beam from an emitter to a receiver (the two black blocks on the module), and detects when this beam is blocked. It is used to detect end-of-travel in 3D printers, CNC machines and robots. It is also used to count the pulses of a slotted disc rotating to calculate motor or wheel speed in robotics and smart cars. In a printer, it detects when a paper is present.

Create a new file in Thonny, with file name photo_interrupter.py. Copy and paste the code below into the file you created.

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print("\nPhoto Interrupter")

# DESCRIPTION

# A photo interrupter module sends infrared light beam from an emitter to a receiver 
# (the two black blocks on the module), and detects when this beam is blocked. 
# It is used to detect end-of-travel in 3D printers, CNC machines and robots. It is
# also used to count the pulses of a slotted disc rotating to calculate motor or wheel
# speed in robotics and smart cars. In a printer, it detects when a paper is present.

# CONNECTIONS REQUIRED

# Connect Photo Interrupter (KY-010) module (labeled 'IR Switch')
#   Pins: GND => GND, VCC => VCC, S => GP28

from machine import Pin
from oled import OLED
from rgbled import RGBLED
from buzzer import Buzzer

sensor = Pin(28, Pin.IN, Pin.PULL_UP)
oled = OLED(scl_pin=15, sda_pin=14)
buzzer = Buzzer(pwm_pin=16)
rgbled = RGBLED(red_pin=12, green_pin=11, blue_pin=10)

counter = 0

try:
    while True:
        rgbled.reset()
        
        # loop while nothing detected
        while sensor.value() == 0: pass
        
        # sensor value is no longer zero => object detected
        counter += 1
        oled.print(f"Counter: {counter}")
        rgbled.set_color(b=255)
        buzzer.play_tone(600)
        
        # loop while object is still present
        while sensor.value() == 1: pass

except KeyboardInterrupt:
    print("\nInterrupted by user!")

finally:
    oled.reset()
    rgbled.reset()
    buzzer.reset()