mdraber
Published © GPL3+

Using Rotary Encoders with Arduino interrupts

Tutorial showing how to use Rotary Encoders and making you realise how different they are from Rotary potentiometers

IntermediateFull instructions provided6,907
Using Rotary Encoders with Arduino interrupts

Things used in this project

Hardware components

Arduino Nano R3
Arduino Nano R3
×1
Rotary Encoder
×1
Custom 7 seg display
×1

Software apps and online services

Arduino IDE
Arduino IDE

Story

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Code

Recognising position and direction of the Rotary Encoder and displaying it in Serial Monitor

Arduino
int counter=0;
String dir="";
unsigned long last_run=0;


void setup() {
  Serial.begin(9600);
  attachInterrupt(digitalPinToInterrupt(3), shaft_moved, FALLING);
  pinMode(4,INPUT);
}

void shaft_moved(){
  if (millis()-last_run>5){
    if (digitalRead(4)==1){
      counter++;
      dir="CW";
      }
    if (digitalRead(4)==0){
      counter--; 
      dir="CCW";}
    last_run=millis();
  }
}

void loop() {
  Serial.print("counter : ");
  Serial.print(counter);
  Serial.print(" direction : ");
  Serial.println(dir);  
}

Rotary encoder. Limiting the counter range to 5 to 10.

Arduino
int counter=5;
String dir="";
unsigned long last_run=0;


void setup() {
  Serial.begin(9600);
  attachInterrupt(digitalPinToInterrupt(3), shaft_moved, FALLING);
  pinMode(4,INPUT);
}

void shaft_moved(){
  if (millis()-last_run>5){
    if (digitalRead(4)==1){
      if(counter<10) counter++;
      dir="CW";
      }
    if (digitalRead(4)==0){
      if (counter>5) counter--; 
      dir="CCW";}
    last_run=millis();
  }
}

void loop() {
  Serial.print("counter : ");
  Serial.print(counter);
  Serial.print(" direction : ");
  Serial.println(dir);  
}

Controlling custom 7 segment display (shift register driven) with Rotary encoder

Arduino
int DS1_pin = 6;
int STCP1_pin =9;
int SHCP1_pin = 8 ;
int DT_pin = 5;

int counter=0;
unsigned long last_run=0;

int digits [10][8]{
  {0,1,1,1,1,1,1,0}, // digit 0
  {0,0,1,1,0,0,0,0}, // digit 1
  {0,1,1,0,1,1,0,1}, // digit 2
  {0,1,1,1,1,0,0,1}, // digit 3
  {0,0,1,1,0,0,1,1}, // digit 4
  {0,1,0,1,1,0,1,1}, // digit 5
  {0,1,0,1,1,1,1,1}, // digit 6
  {0,1,1,1,0,0,0,0}, // digit 7
  {0,1,1,1,1,1,1,1}, // digit 8
  {0,1,1,1,1,0,1,1}  // digit 9
};


void DisplayDigit(int Digit)
{
    digitalWrite(STCP1_pin,LOW);
    for (int i = 7; i>=0; i--)
   {
    digitalWrite(SHCP1_pin,LOW);
    if (digits[Digit][i]==1) digitalWrite(DS1_pin, LOW); 
    if (digits[Digit][i]==0) digitalWrite(DS1_pin, HIGH);
    digitalWrite(SHCP1_pin,HIGH);
   }
   digitalWrite(STCP1_pin, HIGH); 
}

void shaft_moved(){
  if (millis()-last_run>5){
    if (digitalRead(4)==1){
      if (counter<9) counter++; 
    }
    if (digitalRead(4)==0){
      if(counter>0) counter--; 
    }
  last_run=millis();
  }
}

void reset_to_0(){
  counter=0;
}

void setup() {  
  pinMode(DS1_pin, OUTPUT);
  pinMode(STCP1_pin, OUTPUT);
  pinMode(SHCP1_pin, OUTPUT);
  attachInterrupt(digitalPinToInterrupt(3), shaft_moved, LOW);
  attachInterrupt(digitalPinToInterrupt(2), reset_to_0, FALLING);
  pinMode(2,INPUT_PULLUP);
  pinMode(DT_pin,INPUT);
}

void loop() {  
  DisplayDigit(counter);  
} 

Credits

mdraber

mdraber

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