HOW to Use Photo Interrupter on Raspberry Pi with ESP32
Description
This kit contains a photo interrupter which mainly uses 1 ITR-9608 photoelectric switch. It is a photoelectric switch optical switch sensor.
Working Principle
When the paper is put in the slot, C is connected with VCC and the signal end S of the sensor are high levels; then the red LED will be off. Otherwise, the red LED will be on.
Required Components
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| ESP32 Board*1 | ESP32 Expansion Board*1 | Keyestudio DIY Photo Interrupter*1 | 3P Dupont Wire*1 | Micro USB Cable*1 |
Connection Diagram
Test Code
//*************************************************************************************
/*
* Filename : Photo_Interrupt
* Description : Light snap sensor counting
* Auther : http://www.keyestudio.com
*/
int PushCounter = 0; //The count variable is assigned an initial value of 0
int State = 0; //Store the current state of the sensor output
int lastState = 0; //Stores the state of the last sensor output
void setup() {
Serial.begin(9600);//Set the baud rate to 9600
pinMode(15, INPUT);//Set the light snap sensor pin to input mode
}
void loop() {
State = digitalRead(15);//Read current state
if (State != lastState) {//If the state is different from the last read
if (State == 1) {//block the light
PushCounter = PushCounter + 1;//Count + 1
Serial.println(PushCounter);//Print count
}
}
lastState = State;//Update state
}
//*************************************************************************************
Code Explanation
Logic setting:
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Initial Setting |
Set PushCounter to 0 |
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|---|---|---|
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when an object enters the slot |
lastState is 0，State turns into 1; |
Set PushCounter to PushCounter+1 |
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when the object leaves the slot |
lastState is 1，State becomes 0， |
PushCounterdoesn’t change; |
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When the object goes |
lastState is 0, State becomes 1， |
SetPushCounter to PushCounter+1. |
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When the object leaves |
lastState is 1，State turns into 0， |
PushCounter doesn’t change; |
Test Result
Connect the wires according to the experimental wiring diagram, compile and upload the code to the ESP32. After uploading successfully，we will use a USB cable to power on，open the serial monitor and set the baud rate to 9600. We need to press the reset button on the ESP32, then the serial monitor will display the PushCounter data. Every time when the object passes through the slot of the sensor, the PushCounter data will increase by 1 continuously, as shown below;
