Button2

Arduino/ESP library to simplify working with buttons.

• Author: Lennart Hennigs (https://www.lennarthennigs.de)
• Copyright (C) 2017-2022 Lennart Hennigs.
• Released under the MIT license.

Description

This library allows you to use callback functions to track single, double, triple and long clicks. Alternatively, it provides function to use in your main loop(). The library also takes care of debouncing. Using this lib will reduce and simplify your source code significantly.

It has been tested with Arduino, ESP8266 and ESP32 devices.

To see the latest changes to the library please take a look at the Changelog.

If you find this library helpful please consider giving it a ⭐️ at GitHub and/or buy me a ☕️.

Thank you!

How To Use

This library allows you to define a button and uses callback functions to detect different types of button interactions. If you don't want to use callback there are also functions available for using it in your code's main loop().

Definition

• Define the button either using the constructor or the begin() function.

  void begin(byte attachTo, byte buttonMode = INPUT_PULLUP, boolean activeLow  = true);

• You can also reset() a button definition if needed.

Button Types

• You can use the class for "real" buttons (pullup, pulldown, and active low).
• Per default the button pins are defined as INPUT_PULLUP. You can override this upon creation.

   Button2 button;
   button.begin(BUTTON_PIN, INPUT, true);

• You can also the library with other types of buttons, e.g. capacitive touch or ones handled via I2C. See the section on defining custom handlers below.

Callback Handler

• Instead of frequently checking the button state in your main loop() this class allows you to assign callback functions.

• You can define callback functions to track various types of clicks:

  • setTapHandler() will be be called when any click occurs. This is the most basic handler. It ignores all timings built-in the library for double or triple click detection.
  • setChangedHandler(), setPressedHandler() and setReleasedHandler() allow to detect basic interactions.
  • setLongClickDetectedHandler() will be called as soon as the long click timeout has passed.
  • setLongClickHandler() will be called after the button has released.
  • setDoubleClickHandler() and setTripleClickHandler() detect complex interactions.

• All callback function need a Button2 reference parameter. There the reference to the triggered button is stored. This can used to call status fuctions, e.g. wasPressedFor().

• You can use handlers for single or for multiple buttons.

• You can track individual or multiple events with a single handler.

• Please take a look at the included examples (see below) to get an overview over the different callback handlers and their usage.

Longpress Handling

• There are two possible callback functions: setLongClickDetectedHandler() and setLongClickHandler().
• setLongClickDetectedHandler() will be called as soon as the defined timeout has passed.
• setLongClickHandler() will only be called after the button has been released.
• setLongClickDetectedRetriggerable(bool retriggerable) allows you to define whether want to get multiple notifications for a single long click depeding on the timeout.
• getLongClickCount() gets you the number of long clicks – this is useful when retriggerable is set.

The Loop

• For the class to work, you need to call the button's loop() member function in your sketch's loop() function.
• Please see the examples below for more details.

Using an timer interrupt instead

• Alternatively, you can call the button's loop() function via a timer interrupt.
• I haven't tried this extensively, so you are on your own here.
• You need make sure that the interval is quick enough that it can detect your timeouts (see below).
• There is an example for the ESP32 ESP32TimerInterrupt.ino that I tested.

Timeouts

• The default timeouts for events are (in ms):

  #define DEBOUNCE_MS 50
  #define LONGCLICK_MS 200
  #define DOUBLECLICK_MS 300

• You can define your own timeouts by using these setter functions:
  • void setDebounceTime(unsigned int ms)
  • void setLongClickTime(unsigned int ms)
  • void setDoubleClickTime(unsigned int ms)
• There are also getter functions available, if needed.

Using Button2 in the main loop()

• Even though I suggest to use handlers for tracking events, you can also use Button2 to check button's state in the main loop
• bool wasPressed() allows you to check whether the button was pressed
• clickType read(bool keepState = false) gives you the type of click that took place
• clickType wait(bool keepState = false) combines this and halts execution until a button click was detected
• The clickType is an enum defined as...

    enum clickType {
      single_click, 
      double_click, 
      triple_click, 
      long_click,
      empty
    };

• There are also dedicated waits (waitForClick(), waitForDouble(), waitForTriple() and waitForLong()) to detect a sepcific type
• The read() and the wait fuctions will reset the state of wasPressed() unless specified otherwise (via a bool parameter)
• Check out the ButtonLoop example to see it in action

IDs for Button Instances

• Each button instance gets a unique (auto incremented) ID upon creation.
• You can get a buttons' ID via getID().
• Alternatively, you can use setID(int newID) to set a new one. But then you need to make sure that they are unique.

Creating A Custom Button State Handler

• Out of the box Button2 supports regular hardware buttons.
• If you want to add other button types you need to define your own function that tracks the state of the button.
• Use setButtonStateFunction() to assign it to your Button2 instance
• Make the button pin 'VIRTUAL', i.e. by calling button.begin(VIRTUAL_PIN);
• And don't forget to initalize the button as this cannot be handled by Button2
• See ESP32CapacitiveTouch.ino, M5StackCore2CustomHandler, and CustomButtonStateHandler.ino as examples.

Removing detection of click types for good

• If you don't want to track certain click types, just don't use the handlers.
• But if you really don't want it in your compiled code, there is the possibility to tell the compiler to leave it out.
• In Button2.h there are three definitions in the beginning of the file:

// #define _IGNORE_DOUBLE
// #define _IGNORE_TRIPLE
// #define _IGNORE_LONG

• Uncommenting one of them will remove parts of the click detection code.

Examples

• SingleButtonSimple – the most basic example, shows how to assign event handlers
• LongpressHandler – shows how determine the time of a button press
• SingleButton – shows the different event handlers
• MultipleButtons – how to use two buttons
• MultiHandler – how to use a single handler for multiple events
• MultiHandlerTwoButtons – a single handler for multiple buttons
• TrackDualButtonClick – how to detect when two buttons are clicked at the same time
• CustomButtonStateHandler.ino - how to assign your own button handler
• ESP32CapacitiveTouch.ino – how to access the ESP32s capacitive touch handlers
• M5StackCore2CustomHandler - example for the M5Stack Core2 touch buttons
• ESP32TimerInterrupt.ino - how to use a timer interrupt with the library.
• ButtonLoop – how to use the button class in the main loop (I recommend using handlers, but well...)

Class Definition

The button class offers a few additional functions, please take a look at the Class Definition below.

See below the constructors and member functions the library provides:

Button2();
Button2(byte attachTo, byte buttonMode = INPUT_PULLUP, boolean activeLow = true);

void begin(byte attachTo, byte buttonMode = INPUT_PULLUP, boolean activeLow  = true);

void setDebounceTime(unsigned int ms);
void setLongClickTime(unsigned int ms);
void setDoubleClickTime(unsigned int ms);

unsigned int getDebounceTime();
unsigned int getLongClickTime();
unsigned int getDoubleClickTime();
byte getPin();

void reset();

void setButtonStateFunction(StateCallbackFunction f);

void setChangedHandler(CallbackFunction f);
void setPressedHandler(CallbackFunction f);
void setReleasedHandler(CallbackFunction f);

void setTapHandler(CallbackFunction f);
void setClickHandler(CallbackFunction f);
void setDoubleClickHandler(CallbackFunction f);
void setTripleClickHandler(CallbackFunction f);

void setLongClickHandler(CallbackFunction f);
void setLongClickDetectedHandler(CallbackFunction f);
void setLongClickDetectedRetriggerable(bool retriggerable);
void byte getLongClickCount() const;

unsigned int wasPressedFor() const;
boolean isPressed() const;
boolean isPressedRaw() const;

bool wasPressed() const;
clickType read(bool keepState = false);
clickType wait(bool keepState = false);
void waitForClick(bool keepState = false);
void waitForDouble(bool keepState = false);
void waitForTriple(bool keepState = false);
void waitForLong(bool keepState = false);

byte getNumberOfClicks() const;
byte getType() const;
String clickToString(clickType type) const;

int getID() const;
void setID(int newID);

bool operator == (Button2 &rhs);

void loop();

Installation

Open the Arduino IDE choose "Sketch > Include Library" and search for "Button2". Or download the ZIP archive (https://github.com/lennarthennigs/Button2/zipball/master), and choose "Sketch > Include Library > Add .ZIP Library..." and select the downloaded file.

License

MIT License

Copyright (c) 2017-2022 Lennart Hennigs

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.