Rotary encoder strange behaviour

Question

I have problem with results (on serial monitor) of rotary encoder.

I am using Arduino UNO and RotaryEncoder library. When I am running example code serial monitor show proper values when rotating with any speed. I want to use encoder to change volume in Df-player. Problem starts when I want to use this code together with more complicated one - Mp3 player. It actually works only when I am rotating encoder very very slowly

#include <SPI.h>
#include <MFRC522.h>
#include <Arduino.h>
#include <SoftwareSerial.h>
#include <DFRobotDFPlayerMini.h>
#include <RotaryEncoder.h>

#define RST_PIN         9           // Configurable, see typical pin layout above
#define SS_PIN          10          // Configurable, see typical pin layout above

#define PIN_IN1 2
#define PIN_IN2 3

#define ROTARYSTEPS 1
#define ROTARYMIN 0
#define ROTARYMAX 30

const int playPauseButton = 4;
const int shuffleButton = 5;

boolean isPlaying = false;

MFRC522 mfrc522(SS_PIN, RST_PIN);   // Create MFRC522 instance

SoftwareSerial mySoftwareSerial(5, 6); // RX, TX

DFRobotDFPlayerMini myDFPlayer;
void printDetail(uint8_t type, int value);

// Setup a RotaryEncoder with 2 steps per latch for the 2 signal input pins:
RotaryEncoder encoder(PIN_IN1, PIN_IN2, RotaryEncoder::LatchMode::TWO03);

// Last known rotary position.
int lastPos = -1;

//*****************************************************************************************//
void setup() {
  Serial.begin(9600);                                           // Initialize serial communications with the PC, COMMENT OUT IF IT FAILS TO PLAY WHEN DISCONNECTED FROM PC
  mySoftwareSerial.begin(9600);
  SPI.begin();                                                  // Init SPI bus
  mfrc522.PCD_Init();                                              // Init MFRC522 card

  while (! Serial);
  encoder.setPosition(5 / ROTARYSTEPS); // start with the value of 5.

  pinMode(playPauseButton, INPUT_PULLUP);
  pinMode(shuffleButton, INPUT_PULLUP);




  Serial.println(F("Initializing DFPlayer ... (May take 3~5 seconds)"));

  if (!myDFPlayer.begin(mySoftwareSerial)) {  //Use softwareSerial to communicate with mp3.
    Serial.println(F("Unable to begin:"));
    Serial.println(F("1.Please recheck the connection!"));
    Serial.println(F("2.Please insert the SD card!"));
  }
  Serial.println(F("DFPlayer Mini online. Place card on reader to play a spesific song"));

  //myDFPlayer.volume(15);  //Set volume value. From 0 to 30
  //volumeLevel = map(analogRead(volumePot), 0, 1023, 0, 30);   //scale the pot value and volume level
  myDFPlayer.volume(5);
  //prevVolume = volumeLevel;

  //----Set different EQ----
  myDFPlayer.EQ(DFPLAYER_EQ_NORMAL);
  //  myDFPlayer.EQ(DFPLAYER_EQ_POP);
  //  myDFPlayer.EQ(DFPLAYER_EQ_ROCK);
  //  myDFPlayer.EQ(DFPLAYER_EQ_JAZZ);
  //  myDFPlayer.EQ(DFPLAYER_EQ_CLASSIC);
  //  myDFPlayer.EQ(DFPLAYER_EQ_BASS);

}



//*****************************************************************************************//
void loop() {
  encoder.tick();

  // get the current physical position and calc the logical position
  int newPos = encoder.getPosition() * ROTARYSTEPS;
 
  if (newPos < ROTARYMIN) {
    encoder.setPosition(ROTARYMIN / ROTARYSTEPS);
    newPos = ROTARYMIN;

  } else if (newPos > ROTARYMAX) {
    encoder.setPosition(ROTARYMAX / ROTARYSTEPS);
    newPos = ROTARYMAX;
  } // if

  if (lastPos != newPos) {
    Serial.println(newPos);
    myDFPlayer.volume(newPos);
    lastPos = newPos;
  } // if


  // Prepare key - all keys are set to FFFFFFFFFFFFh at chip delivery from the factory.
  MFRC522::MIFARE_Key key;
  for (byte i = 0; i < 6; i++) key.keyByte[i] = 0xFF;

  //some variables we need
  byte block;
  byte len;
  MFRC522::StatusCode status;



  if (digitalRead(playPauseButton) == LOW) {
    if (isPlaying) {
      myDFPlayer.pause();
      isPlaying = false;
      Serial.println("Paused..");
    }
    else {
      isPlaying = true;
      myDFPlayer.start();
      Serial.println("Playing..");
    }
    delay(500);
  }


  if (digitalRead(shuffleButton) == LOW) {
    myDFPlayer.randomAll();
    Serial.println("Shuffle Play");
    isPlaying = true;
    delay(1000);
  }


  //-------------------------------------------

  // Reset the loop if no new card present on the sensor/reader. This saves the entire process when idle.
  if ( mfrc522.PICC_IsNewCardPresent()) {



    // Select one of the cards
    if ( ! mfrc522.PICC_ReadCardSerial()) {
      return;
    }

    Serial.println(F("**Card Detected:**"));

    //-------------------------------------------

    mfrc522.PICC_DumpDetailsToSerial(&(mfrc522.uid)); //dump some details about the card

    //mfrc522.PICC_DumpToSerial(&(mfrc522.uid));      //uncomment this to see all blocks in hex

    //-------------------------------------------

    Serial.print(F("Number: "));


    //---------------------------------------- GET NUMBER AND PLAY THE SONG

    byte buffer2[18];
    block = 1;
    len = 18;

    status = mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, 1, &key, &(mfrc522.uid)); //line 834
    if (status != MFRC522::STATUS_OK) {
      Serial.print(F("Authentication failed: "));
      Serial.println(mfrc522.GetStatusCodeName(status));
      return;
    }

    status = mfrc522.MIFARE_Read(block, buffer2, &len);
    if (status != MFRC522::STATUS_OK) {
      Serial.print(F("Reading failed: "));
      Serial.println(mfrc522.GetStatusCodeName(status));
      return;
    }


    //PRINT NUMBER
    String number = "";

    for (uint8_t i = 0; i < 16; i++)
    {
      number += (char)buffer2[i];
    }
    number.trim();
    Serial.print(number);

    //PLAY SONG

    myDFPlayer.play(number.toInt());
    isPlaying = true;



    //----------------------------------------

    Serial.println(F("\n**End Reading**\n"));

    delay(1000); //change value if you want to read cards faster

    mfrc522.PICC_HaltA();
    mfrc522.PCD_StopCrypto1();
  }
}

Any ideas what is wrong?

Answer 1

You have a delay(1000) in your main loop, and since your RotaryEncoder object seems to need a tick() function, i am assuming that it is not interrupt driven. This means that it will check only once per second if it has moved to the next step.

If a rotary encoder is stepped twice, and the middle step is missed by the MCU, the latter has no way of knowing which way round the encoder has turned.

So in this case you can only turn it one step per second.

What you need is, either:

• a free running main loop, which goes round at least 100 times per second. (less nice)
• a rotary encoder driver that is interrupt driven. (very nice)

I don't know if such a library exists, because i tend not to use arduino libs, but it is a very good exercise to write your own using GPIO interrupts.