Keypad.h

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#ifndef KEYPAD_H
#define KEYPAD_H

template<int PIN, uint16_t DEBOUNCE = 50>
class Keypad {
public:
  Keypad(const uint16_t* map = NULL) :
    m_timestamp(0),
    m_key(0),
    m_map(map)
  {
  }

  bool ischanged()
  {
    // Check if debounce time limit has elapsed
    if (millis() - m_timestamp < DEBOUNCE) return (false);
    m_timestamp = millis();

    // Read the analog pin and map
    uint16_t value = analogRead(PIN);
    uint8_t key = 0;
    if (m_map == NULL) return (false);
    while (value < (uint16_t) pgm_read_word(&m_map[key])) key++;
    if (key == m_key) return (false);
    m_key = key;
    return (true);
  }

  uint8_t key()
    __attribute__((always_inline))
  {
    return (m_key);
  }

  uint16_t timestamp()
    __attribute__((always_inline))
  {
    return (m_timestamp);
  }

protected:
  uint16_t m_timestamp;

  uint8_t m_key;

  const uint16_t* m_map;
};

#endif