/* Tiny85 encoder 
 *
 * pin I2C: SDA = 5 = PB0; SCL = 7 = PB2
 * pin Enc: A = PB3; B =  PB4; Switch = PB1 
 *
 */
 
#include <TinyWireM.h>
#include "avr/interrupt.h"; 
#include <Tiny4kOLED.h>
 
#define TARGET_ADDR   0x08
#define encA 3
#define encB 4
#define swtc 1
 
volatile byte currentValue = 0;
int Valore = 0;
volatile int  lastEncoded  = 0;
volatile byte lastValue    = 0;
volatile byte lastSwitch   = 0;
 
void setup() {
  TinyWireM.begin();
 

  oled.begin(128, 64, sizeof(tiny4koled_init_128x64br), tiny4koled_init_128x64br);

  // Two fonts are supplied with this library, FONT8X16 and FONT6X8
  oled.setFont(FONT6X8);

  // To clear all the memory
  oled.clear();
  oled.on();


  delay(3000);
  prepareDisplay();

  pinMode(encA, INPUT_PULLUP);
  pinMode(encB, INPUT_PULLUP);
  pinMode(swtc, INPUT_PULLUP);
  digitalWrite(encA, HIGH);
  digitalWrite(encB, HIGH);
  
  GIMSK = 0b00100000;       // Enable pin interrupts
  PCMSK = 0b00011010;       // Enable pin interrupt PB3,PB4,PB1
  sei();                    // Turn on interrupts
}
 
void loop() {
  byte currentSwitch = digitalRead(swtc);
 
  if ((lastValue != currentValue)||(lastSwitch != currentSwitch)) {
    TinyWireM.beginTransmission(TARGET_ADDR);
    TinyWireM.send(currentValue);
    TinyWireM.send(currentSwitch);
    TinyWireM.endTransmission();
    
    lastValue  = currentValue;
    lastSwitch = currentSwitch;

    if (lastSwitch == 0) Valore = 0;
      unsigned int i, k;
  unsigned char ch[5];
 oled.clear();
  oled.begin();

  oled.setCursor(20, 1);
  oled.print(F("ATtiny85+SSD1306"));
  oled.setCursor(20, 2);
  oled.print(F("Prova encoder "));

  
  oled.setCursor(57, 4);
  oled.print(Valore);
  oled.setCursor(57, 5);
  oled.print(currentSwitch);

  }
  delay(10);
}

void prepareDisplay() {
  unsigned int i, k;
  unsigned char ch[5];

  

  
}
 
ISR(PCINT0_vect) {
  byte MSB = digitalRead(encA); //MSB = most significant bit
  byte LSB = digitalRead(encB); //LSB = least significant bit
   
  int encoded = (MSB << 1) |LSB; //converting the 2 pin 
                                 //value to single number
  int sum  = (lastEncoded << 2) | encoded; //adding it to 
                                           //the previous
                                           //encoded value
  
  if(sum==0b1101||sum==0b0100||sum==0b0010||sum==0b1011) currentValue++;
  if(sum==0b1110||sum==0b0111||sum==0b0001||sum==0b1000) currentValue--;
  if(sum==0b1101||sum==0b0100||sum==0b0010||sum==0b1011) Valore++;
  if(sum==0b1110||sum==0b0111||sum==0b0001||sum==0b1000) Valore--;
  lastEncoded = encoded; //store this value for next time
}