Adding keypad (resistor ladder) support

Author: mikaelpatel

README.md

@@ -5,22 +5,24 @@ instruction and execute in 1-2 clock cycles. The library functions are
 more than 10 times faster than the Arduino digital pin functions. In
 some cases as much as 100 times faster.
 
-Additional support classes are available for Debounced Button, Shift
-Register Input/Output, and Software Serial. These also demonstrate how
-the GPIO template class may be used to construct additional libraries.
+Additional support classes are available for Debounced Button/Keypad,
+Shift Register Input/Output, and Software Serial. These also
+demonstrate how the GPIO template class may be used to construct
+additional libraries.
 
 This library supports boards based on SAM3X8E, ATmega168, ATmega328P,
 ATmega32U4, ATmega1280, ATmega2560, ATtinyX4 and ATtinyX5.
 
-Version: 1.10
+Version: 1.11
 
 ## Classes
 
 * [AVR Board Configuration, BOARD](./src/Hardware/AVR/Board.h)
 * [AVR General Purpose Input/Output, GPIO](./src/Hardware/AVR/GPIO.h)
 * [SAM Board Configuration, BOARD](./src/Hardware/SAM/Board.h)
 * [SAM General Purpose Input/Output, GPIO](./src/Hardware/SAM/GPIO.h)
-* [Debounced Input Pin, Button](./src/Button.h)
+* [Debounced Digital Pin, Button](./src/Button.h)
+* [Debounced Analog Pin, Keypad](./src/Keypad.h)
 * [Shift Register Parallel Input, SRPI](./src/SRPI.h)
 * [Shift Register Parallel Input/Output, SRPIO](./src/SRPIO.h)
 * [Shift Register Parallel Output, SRPO](./src/SRPO.h)
@@ -48,8 +50,9 @@ shiftOut | 103/160 | srpo << val | 8 | 13/20
 
 ## Usage
 
-* [Arduino-OWI](https://github.com/mikaelpatel/Arduino-OWI)
 * [Arduino-DHT](https://github.com/mikaelpatel/Arduino-DHT)
+* [Arduino-LCD](https://github.com/mikaelpatel/Arduino-LCD)
+* [Arduino-OWI](https://github.com/mikaelpatel/Arduino-OWI)
 * [Arduino-RTC](https://github.com/mikaelpatel/Arduino-RTC)
 * [Arduino-SPI](https://github.com/mikaelpatel/Arduino-SPI)
 * [Arduino-Storage](https://github.com/mikaelpatel/Arduino-Storage)

library.properties

@@ -1,9 +1,9 @@
 name=Arduino-GPIO
-version=1.10
+version=1.11
 author=Mikael Patel
 maintainer=Mikael Patel <[email protected]>
 sentence=General Purpose Input/Output (GPIO) library for Arduino.
-paragraph=The GPIO library has been developed to allow high performance digital pin access. Most access functions are compiled to a single instruction and execute in 1-2 clock cycles. The library functions are more than 10 times faster than the Arduino digital pin functions. In some cases as much as 100 times faster. Additional support classes are available for Debounced Button, Shift Register Parallel Input/Output and Software Serial. These also demonstrate how the GPIO template class may be used to construct additional libraries.
+paragraph=The GPIO library has been developed to allow high performance digital pin access. Most access functions are compiled to a single instruction and execute in 1-2 clock cycles. The library functions are more than 10 times faster than the Arduino digital pin functions. In some cases as much as 100 times faster. Additional support classes are available for Debounced Button/Keypad, Shift Register Parallel Input/Output and Software Serial. These also demonstrate how the GPIO template class may be used to construct additional libraries.
 category=Communication
 url=https://github.com/mikaelpatel/Arduino-GPIO
 architectures=avr,sam

mainpage.dox

@@ -6,15 +6,16 @@ instruction and execute in 1-2 clock cycles. The library functions are
 more than 10 times faster than the Arduino digital pin functions. In
 some cases as much as 100 times faster.
 
-Additional support classes are available for Debounced Button, Shift
-Register Parallel Input and Output (SRPI, SRPO and SRPIO), and Serial
-(Software::Serial). These also demonstrate how the GPIO template class
-may be used to construct additional classes and libraries.
+Additional support classes are available for Debounced Button/Keypad,
+Shift Register Parallel Input and Output (SRPI, SRPO and SRPIO), and
+Serial (Software::Serial). These also demonstrate how the GPIO
+template class may be used to construct additional classes and
+libraries.
 
 This library supports boards based on SAM3X8E, ATmega168, ATmega328P,
 ATmega32U4, ATmega1280, ATmega2560, ATtinyX4 and ATtinyX5.
 
-Version: 1.10
+Version: 1.11
 */
 
 /** @page License

src/Keypad.h

@@ -0,0 +1,92 @@
+/**
+ * @file Keypad.h
+ * @version 1.0
+ *
+ * @section License
+ * Copyright (C) 2017, Mikael Patel
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ */
+
+#ifndef KEYPAD_H
+#define KEYPAD_H
+
+/**
+ * Resistor ladder keypad read and debounce template class.
+ * @param[in] PIN analog pin.
+ * @param[in] DEBOUNCE time limit (default 50 ms).
+ */
+template<int PIN, uint16_t DEBOUNCE = 50>
+class Keypad {
+public:
+  /**
+   * Construct keypad with given template parameters.
+   */
+  Keypad(const uint16_t* map = NULL) :
+    m_timestamp(0),
+    m_key(0),
+    m_map(map)
+  {
+  }
+
+  /**
+   * Check if it is time to sample the keypad and check for
+   * key pressed/release.
+   * @return true(1) if a change was detected, otherwise false(0).
+   */
+  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);
+  }
+
+  /**
+   * Return latest key.
+   * @return key number.
+   */
+  uint8_t key()
+    __attribute__((always_inline))
+  {
+    return (m_key);
+  }
+
+  /**
+   * Return debounce timestamp.
+   * @return timestamp.
+   */
+  uint16_t timestamp()
+    __attribute__((always_inline))
+  {
+    return (m_timestamp);
+  }
+
+protected:
+  /** Timestamp for latest pin read. */
+  uint16_t m_timestamp;
+
+  /** Latest debounced key. */
+  uint8_t m_key;
+
+  /** Key map; program memory with values in descent order. */
+  const uint16_t* m_map;
+};
+
+#endif