// https://wokwi.com/projects/357828229247849473
// https://forum.arduino.cc/t/uno-vs-mega-with-a-rotary-encoder/1095187
/*
// digital pins 2 and 3
# define PINX PINE
# define maskAB 0x30
# define maskB 0x10
# define maskA 0x20
# define pinA 2
# define pinB 3
*/
// digital pins 18 and 19
# define PINX PIND
# define maskAB 0x0c
# define maskB 0x04
# define maskA 0x08
# define pinA 19
# define pinB 18
/*
// digital pins 20 and 21
# define PINX PIND
# define maskAB 0x03
# define maskB 0x01
# define maskA 0x02
# define pinA 21
# define pinB 20
/**/
volatile byte aFlag = 0; // let's us know when we're expecting a rising edge on pinA to signal that the encoder has arrived at a detent
volatile byte bFlag = 0; // let's us know when we're expecting a rising edge on pinB to signal that the encoder has arrived at a detent (opposite direction to when aFlag is set)
volatile byte encoderPos = 0; //this variable stores our current value of encoder position. Change to int or uin16_t instead of byte if you want to record a larger range than 0-255
volatile byte oldEncPos = 0; //stores the last encoder position value so we can compare to the current reading and see if it has changed (so we know when to print to the serial monitor)
volatile byte reading = 0; //somewhere to store the direct values we read from our interrupt pins before checking to see if we have moved a whole detent
void setup() {
pinMode(pinA, INPUT_PULLUP); // set pinA as an input, pulled HIGH to the logic voltage (5V or 3.3V for most cases)
pinMode(pinB, INPUT_PULLUP); // set pinB as an input, pulled HIGH to the logic voltage (5V or 3.3V for most cases)
attachInterrupt(digitalPinToInterrupt(pinA),PinA,RISING); // set an interrupt on PinA, looking for a rising edge signal and executing the "PinA" Interrupt Service Routine (below)
attachInterrupt(digitalPinToInterrupt(pinB),PinB,RISING); // set an interrupt on PinB, looking for a rising edge signal and executing the "PinB" Interrupt Service Routine (below)
Serial.begin(9600); // start the serial monitor link
Serial.println("-------------rotaryEncoderWorkup_v1.1-------------------");
Serial.println(encoderPos);
}
void PinA(){ //from interrupt above
reading = PINX & maskAB; // read all eight pin values then strip away all but pinA and pinB's values
if(reading == maskAB && aFlag) { //check that we have both pins at detent (HIGH) and that we are expecting detent on this pin's rising edge
encoderPos --; //decrement the encoder's position count
if (encoderPos>18){encoderPos=18;}
bFlag = 0; //reset flags for the next turn
aFlag = 0; //reset flags for the next turn
}
else if (reading == maskB) bFlag = 1; //signal that we're expecting pinB to signal the transition to detent from free rotation
}
void PinB(){ //from interrupt above
reading = PINX & maskAB; //read all eight pin values then strip away all but pinA and pinB's values
if (reading == maskAB && bFlag) { //check that we have both pins at detent (HIGH) and that we are expecting detent on this pin's rising edge
encoderPos ++; //increment the encoder's position count
if (encoderPos>18){encoderPos=0;}
bFlag = 0; //reset flags for the next turn
aFlag = 0; //reset flags for the next turn
}
else if (reading == maskA) aFlag = 1; //signal that we're expecting pinA to signal the transition to detent from free rotation
}
void loop(){
if(oldEncPos != encoderPos) {
Serial.println(encoderPos);
oldEncPos = encoderPos;
}
}