Complete Build Guide

/*
 * DIY Foot Pedal Water Tap Controller
 * Three modes:
 * - Hold pedal: Water flows while pressed
 * - Single tap: Continuous flow for 2 minutes (auto-shutoff)
 * - Double tap: Switch to manual hand control
 */

// Pin definitions
const int FOOT_PEDAL_PIN = 2;     // Foot pedal switch (interrupt capable)
const int HOT_VALVE_PIN = 9;       // Hot water solenoid valve
const int COLD_VALVE_PIN = 10;     // Cold water solenoid valve
const int STATUS_LED_PIN = 13;     // Status indicator LED

// Timing constants
const unsigned long DEBOUNCE_DELAY = 50;      // Debounce time in ms
const unsigned long DOUBLE_TAP_WINDOW = 400;  // Time window for double tap (ms)
const unsigned long TAP_THRESHOLD = 200;      // Max press time for "tap" vs "hold" (ms)
const unsigned long CONTINUOUS_TIMEOUT = 120000; // 2 minutes in ms

// State variables
enum Mode { HOLD_MODE, CONTINUOUS_MODE, MANUAL_MODE };
Mode currentMode = HOLD_MODE;

unsigned long buttonPressTime = 0;
unsigned long buttonReleaseTime = 0;
unsigned long lastTapTime = 0;
unsigned long continuousStartTime = 0;

bool buttonState = HIGH;
bool lastButtonState = HIGH;
bool valvesOpen = false;
int tapCount = 0;

void setup() {
  // Initialize pins
  pinMode(FOOT_PEDAL_PIN, INPUT_PULLUP);
  pinMode(HOT_VALVE_PIN, OUTPUT);
  pinMode(COLD_VALVE_PIN, OUTPUT);
  pinMode(STATUS_LED_PIN, OUTPUT);

  // Ensure valves are closed on startup
  closeValves();

  // Initialize serial for debugging
  Serial.begin(9600);
  Serial.println("Foot Pedal Water Tap Controller Started");
  Serial.println("Mode: HOLD");
}

void loop() {
  // Read button with debounce
  int reading = digitalRead(FOOT_PEDAL_PIN);

  // Button state changed
  if (reading != lastButtonState) {
    delay(DEBOUNCE_DELAY); // Simple debounce
    reading = digitalRead(FOOT_PEDAL_PIN);

    if (reading != buttonState) {
      buttonState = reading;

      // Button pressed (goes LOW due to pull-up)
      if (buttonState == LOW) {
        buttonPressTime = millis();
      }
      // Button released
      else {
        buttonReleaseTime = millis();
        handleButtonRelease();
      }
    }
  }

  lastButtonState = reading;

  // Handle current mode
  switch (currentMode) {
    case HOLD_MODE:
      handleHoldMode();
      break;

    case CONTINUOUS_MODE:
      handleContinuousMode();
      break;

    case MANUAL_MODE:
      handleManualMode();
      break;
  }

  // Update status LED (blink pattern indicates mode)
  updateStatusLED();
}

void handleButtonRelease() {
  unsigned long pressDuration = buttonReleaseTime - buttonPressTime;
  unsigned long timeSinceLastTap = buttonReleaseTime - lastTapTime;

  // Detect tap (quick press/release)
  if (pressDuration < TAP_THRESHOLD) {
    // Check if this is a second tap within the double-tap window
    if (timeSinceLastTap < DOUBLE_TAP_WINDOW && tapCount == 1) {
      // Double tap detected
      handleDoubleTap();
      tapCount = 0;
    } else {
      // Single tap (might become double tap)
      tapCount = 1;
      lastTapTime = buttonReleaseTime;

      // Wait to see if there's a second tap
      delay(DOUBLE_TAP_WINDOW);

      // If still just one tap, treat as single tap
      if (tapCount == 1) {
        handleSingleTap();
        tapCount = 0;
      }
    }
  } else {
    // Long press (hold mode handled in real-time)
    tapCount = 0;
  }
}

void handleSingleTap() {
  Serial.println("Single Tap - Entering CONTINUOUS mode");
  currentMode = CONTINUOUS_MODE;
  continuousStartTime = millis();
  openValves();
}

void handleDoubleTap() {
  Serial.println("Double Tap - Entering MANUAL mode");
  currentMode = MANUAL_MODE;
  closeValves();

  // Flash LED twice to indicate manual mode
  for (int i = 0; i < 2; i++) {
    digitalWrite(STATUS_LED_PIN, HIGH);
    delay(100);
    digitalWrite(STATUS_LED_PIN, LOW);
    delay(100);
  }
}

void handleHoldMode() {
  // Water flows while button is held down
  if (buttonState == LOW) {
    if (!valvesOpen) {
      openValves();
    }
  } else {
    if (valvesOpen) {
      closeValves();
    }
  }
}

void handleContinuousMode() {
  // Check for timeout (2 minutes)
  if (millis() - continuousStartTime >= CONTINUOUS_TIMEOUT) {
    Serial.println("Continuous timeout - Returning to HOLD mode");
    currentMode = HOLD_MODE;
    closeValves();
    return;
  }

  // Check if button pressed to stop
  if (buttonState == LOW && valvesOpen) {
    Serial.println("Button pressed - Stopping continuous flow");
    currentMode = HOLD_MODE;
    closeValves();
  }
}

void handleManualMode() {
  // In manual mode, foot pedal returns control to faucet
  // Pressing pedal exits manual mode
  if (buttonState == LOW) {
    Serial.println("Exiting MANUAL mode - Returning to HOLD mode");
    currentMode = HOLD_MODE;
  }
}

void openValves() {
  digitalWrite(HOT_VALVE_PIN, HIGH);
  digitalWrite(COLD_VALVE_PIN, HIGH);
  valvesOpen = true;
  Serial.println("Valves OPEN");
}

void closeValves() {
  digitalWrite(HOT_VALVE_PIN, LOW);
  digitalWrite(COLD_VALVE_PIN, LOW);
  valvesOpen = false;
  Serial.println("Valves CLOSED");
}

void updateStatusLED() {
  static unsigned long lastBlinkTime = 0;
  static bool ledState = false;
  unsigned long currentMillis = millis();

  switch (currentMode) {
    case HOLD_MODE:
      // Solid on when valves open, off when closed
      digitalWrite(STATUS_LED_PIN, valvesOpen ? HIGH : LOW);
      break;

    case CONTINUOUS_MODE:
      // Fast blink (500ms interval)
      if (currentMillis - lastBlinkTime >= 500) {
        ledState = !ledState;
        digitalWrite(STATUS_LED_PIN, ledState);
        lastBlinkTime = currentMillis;
      }
      break;

    case MANUAL_MODE:
      // Slow blink (1000ms interval)
      if (currentMillis - lastBlinkTime >= 1000) {
        ledState = !ledState;
        digitalWrite(STATUS_LED_PIN, ledState);
        lastBlinkTime = currentMillis;
      }
      break;
  }
}