SH1106_OLED_counter.cpp

/*
 * ESP32 Counter with OLED Display and Encoder
 *
 * Hardware required:
 * - ESP32 development board
 * - SH1106 128x64 OLED Display (I2C)
 * - Rotary Encoder with push button
 * - 2 additional buttons
 *
 * Wiring:
 * ESP32              Component
 * ------------------------------------
 * GPIO16 (RX2)       Encoder Push
 * GPIO17             Encoder A
 * GPIO18             Encoder B
 * GPIO25             BACK Button
 * GPIO26             CONFIRM Button
 * GPIO21 (SDA)       OLED SDA
 * GPIO22 (SCL)       OLED SCL
 * 3.3V               VCC (OLED, Encoder, Buttons)
 * GND                GND (All components)
 *
 * Functionality:
 * 1. Encoder rotation changes counter value
 * 2. Any button press (encoder push, BACK, or CONFIRM) resets counter to 0
 * 3. Display shows current value (divided by 2 for smoother counting)
 * 4. Serial monitor shows detailed counter updates
 */

#include <Arduino.h>
#include <Wire.h>
#include <U8g2lib.h>

// Pin definitions
const uint8_t ENC_PUSH = 16;    // Encoder push button
const uint8_t ENC_A = 17;       // Encoder signal A
const uint8_t ENC_B = 18;       // Encoder signal B
const uint8_t BTN_BACK = 25;    // Back button
const uint8_t BTN_CONFIRM = 26; // Confirm button

// Global variables
volatile int32_t encoderValue = 0;
volatile uint8_t lastEncA = HIGH;
volatile uint8_t lastEncB = HIGH;
int lastEncPush = HIGH;
int lastBackBtn = HIGH;
int lastConfirmBtn = HIGH;

// Initialize OLED display
U8G2_SH1106_128X64_NONAME_F_HW_I2C display(U8G2_R0, U8X8_PIN_NONE);

// Encoder interrupt service routine
void IRAM_ATTR encoderISR() {
  uint8_t a = digitalRead(ENC_A);
  uint8_t b = digitalRead(ENC_B);
  
  if (a != lastEncA) {
    lastEncA = a;
    if (a != b) {
      encoderValue++;
    } else {
      encoderValue--;
    }
  }
}

// Display update function
void updateDisplay(int32_t value) {
  display.clearBuffer();
  char str[10];
  sprintf(str, "%d", value / 2);
  display.drawStr(10, 35, str);
  display.sendBuffer();
}

void setup() {
  // Initialize serial communication
  Serial.begin(115200);
  Serial.println("ESP32 Counter Example Starting...");
  
  // Configure pins
  pinMode(ENC_PUSH, INPUT_PULLUP);
  pinMode(ENC_A, INPUT_PULLUP);
  pinMode(ENC_B, INPUT_PULLUP);
  pinMode(BTN_BACK, INPUT_PULLUP);
  pinMode(BTN_CONFIRM, INPUT_PULLUP);
  
  // Initialize display
  display.begin();
  display.setFont(u8g2_font_ncenB14_tr);
  updateDisplay(0);
  
  // Attach encoder interrupt
  attachInterrupt(digitalPinToInterrupt(ENC_A), encoderISR, CHANGE);
  
  Serial.println("Setup complete. Rotate encoder or press any button.");
}

void loop() {
  static int32_t lastDisplayedValue = 0;
  
  // Update display if value changed
  if (encoderValue != lastDisplayedValue) {
    Serial.printf("Encoder value: %d (displayed: %d)\n", encoderValue, encoderValue / 2);
    updateDisplay(encoderValue);
    lastDisplayedValue = encoderValue;
  }

  // Read all buttons
  int encPush = digitalRead(ENC_PUSH);
  int backBtn = digitalRead(BTN_BACK);
  int confirmBtn = digitalRead(BTN_CONFIRM);

  // Check for button presses and reset counter
  if ((encPush != lastEncPush && encPush == LOW) ||
      (backBtn != lastBackBtn && backBtn == LOW) ||
      (confirmBtn != lastConfirmBtn && confirmBtn == LOW)) {
    encoderValue = 0;
    updateDisplay(encoderValue);
    Serial.println("Counter reset by button press");
  }

  // Update button states
  lastEncPush = encPush;
  lastBackBtn = backBtn;
  lastConfirmBtn = confirmBtn;
}