Editorial Solution

From the task, we will be using the two buttons for incrementing and decrementing the count.
We will also store the value in the EEPROM so that the value is retained over power off/reset.
We will also implement a proper debounce logic on both buttons to correctly read one press instead of dangling presses.
We will increase and decrease the count value based on the corresponding button press.

System Setup

Code

#include <EEPROM.h>

// Pin Definitions
#define INC_BUTTON_PIN 2  // Button to increment count
#define DEC_BUTTON_PIN 3  // Button to decrement count

// Variables
int humanCount;               // Current human count
const int eepromAddress = 0;  // EEPROM address to store the count

void setup() {
  Serial.begin(9600);
  initiateCount();

  // Configure button pins
  pinMode(INC_BUTTON_PIN, INPUT_PULLUP);
  pinMode(DEC_BUTTON_PIN, INPUT_PULLUP);

  Serial.println("Human Counter System Started!");
  Serial.print("Initial Count: ");
  Serial.println(humanCount);
}


void loop() {
  static bool incButtonState = HIGH;
  static bool decButtonState = HIGH;


  // Read button states with debounce
  bool incButtonPressed = debounceButton(INC_BUTTON_PIN, incButtonState);
  bool decButtonPressed = debounceButton(DEC_BUTTON_PIN, decButtonState);


  // Increment count
  if (incButtonPressed) {
    humanCount++;
    updateEEPROM();
    Serial.print("Count Incremented: ");
    Serial.println(humanCount);
  }

  // Decrement count
  if (decButtonPressed && humanCount > 0) {
    humanCount--;
    updateEEPROM();
    Serial.print("Count Decremented: ");
    Serial.println(humanCount);
  }
}


bool debounceButton(int pin, bool &lastState) {
  bool currentState = digitalRead(pin);
  if (lastState != currentState) {
    delay(50);  // Debounce delay
    if (digitalRead(pin) == currentState) {
      lastState = currentState;
      return currentState == LOW;  // Return true if button is pressed
    }
  }
  return false;
}


void updateEEPROM() {
  EEPROM.write(eepromAddress, humanCount);
}

void initiateCount() {
  humanCount = EEPROM.read(eepromAddress);
  if (humanCount == 255) {
    humanCount = 0;
    updateEEPROM();
  }
}

Code Explanation

Debouncing Logic:

Prevent multiple triggers by introducing a delay (50ms) after detecting a button state change:
- The condition if (lastState != currentState) checks whether the button's state has changed (e.g., from HIGH to LOW or vice versa). This ensures that further checks only occur when a button press or release is detected.
- The delay(50) introduces a 50ms delay to filter out noise and stabilize the input signal. Mechanical buttons often "bounce" rapidly between states when pressed, causing false triggers if read immediately.
- After the delay, the logic re-checks the pin state with if (digitalRead(pin) == currentState). If the state remains the same as currentState, it confirms that the button input is stable.
- lastState = currentState updates the last recorded state to the current stable state. The line return currentState == LOW checks if the button is pressed (LOW logic) and returns true if so.

if (lastState != currentState) {
  delay(50); // Debounce delay
  if (digitalRead(pin) == currentState) {
    lastState = currentState;
    return currentState == LOW;  // Return true if button is pressed
  }
}

Output Video

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