Raspberry PI Optical Gate Control Code

Optical gates are basicly an infra LED and photo sensor facing eachother. If infrawave is sensed then the optical gate is open. It is closed otherwise. If everything functions normally a closed optical gate means something is blocking the space between the infra LED and photo sensor. They are widely used for counting objects.

raspberry pi with optical gate
Figure 1 - Raspberry PI with Optical gate

Required hardware

  • Raspberry PI
  • Optical gate
  • Resistors: 100Ω, 100kΩ

Source code to install on controller

#!/usr/bin/python
import RPi.GPIO as GPIO
import time
GPIO.setmode(GPIO.BCM)

def my_callback(channel):
        global i        
        i = i+1
        
def main():
        

        GPIO.setup(27, GPIO.OUT)
        GPIO.setup(17, GPIO.IN)

        led = GPIO.PWM(27, 100)

        GPIO.add_event_detect(17, GPIO.BOTH, callback=my_callback)
        try:
                global i

                i = 0
                led.start(50)
                while True:
                        if i <= 17:
                                print ('Signal')                                
                        i = 0                
                        time.sleep(0.1)                                

        except KeyboardInterrupt:
                led.stop()   
                GPIO.cleanup()
if __name__ == "__main__":
    main()

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