r89m MPR121 Button

This library makes working with MPR121 buttons easy.

Easily handle button events such as onPress, onHold, onHoldRepeat and onRelease. The same callback functions can be used with multiple buttons, helping to keep your code cleaner and more manageable.

This library relies on you having both r89m Buttons and MPR121 libraries downloaded and available to the Arduino IDE.

Examples

Checkout the examples folder to show you how easy it is to use!

Constructor

###MPR121Button(Adafruit_MPR121& touch_ic, uint8_t electrode)

Methods

boolean update()

Update the button state - this will call any callbacks that are necessary. Returns true if the state changes.

###void update(uint16_t touch_status) Update the button state with the given touch_status. This allows several buttons to be updated whilst only communicating with the MPR121 chip once. See the FastRead example for more information.

boolean is(Button& btn)

Return whether or not the button is the same as the btn passed

boolean isPressed()

Return whether or not the button is currently pressed.

Callbacks

CallbackAttachedResponse onPress(onPressCallbackFunction)

onPressCallbackFunction is a function which will be called as soon as the button is pressed. It must be defined with the parameters shown below

void callThisFunctionOnPress(Button& btn){
  // btn is a reference to the button that was pressed.
}

CallbackAttachedResponse onRelease

There are 3 variations of onRelease:

CallbackAttachedResponse onRelease(onReleaseCallbackFunction)

onReleaseCallbackFunction is a function which is called when the button is released. It must be defined with the parameters shown below

void callThisFunctionOnRelease(Button& btn, uint_16t duration){
  // btn is a reference to the button that was pressed
  // duration is how long the button was pressed for
}

CallbackAttachedResponse onRelease(uint_16t wait, onReleaseCallbackFunction)

As above, plus:

wait if the button is held for at-least waitms onReleaseCallbackFunction will be called.

CallbackAttachedResponse onRelease(uint_16t wait, uint_16t max_wait, onReleaseCallbackFunction)

As above, plus:

max_wait if the button is held for more than max_waitms onReleaseCallbackFunction will not be called.

CallbackAttachedResponse onHold(uint_16t duration, onHoldCallbackFunction)

duration how long the button must be held before onHoldCallbackFunction is called. onHoldCallbackFunction is a function which is called when the button is held. It must be defined with the parameters shown below

void callThisFuntionOnHold(Button& btn, uint_16t duration){
  // btn is a reference to the button that was held
  // duration is how long the button was held for
}

CallbackAttachedResponse onHoldAndRepeat(uint_16t duration, uint_16t repeat_every, onHoldAndRepeatCallbackFunction)

duration how long the button must be held before onHoldAndRepeatCallbackFunction is called. repeat_every how long to wait before onHoldAndRepeatCallbackFunction is called repeatedly. onHoldAndRepeatCallbackFunction is a function which is called repeatedly when the button is held. It must be defined with the parameters shown below

void callThisFunctionOnHoldAndRepeat(Button& btn, uint16_t duration, uint8_t repeat_count){
  // btn is a reference to the button that was held
  // duration is how long the button has been held for
  // repeat_count is the number of times the callback has been called
}

Enums

CallbackAttachedResponse

attSuccessful returned when a callback has successfully been attached

attNoMoreRoom returned when a callback could not be attached because there is not enough room. Check MAX_CALLBACKS_PER_BUTTON.

Constants

MAX_CALLBACKS_PER_BUTTON (default=3)

Defines the maximum number of callbacks per button. Increasing this number will allow more callbacks but will use marginally more memory and processing power. This can be changed on a sketch by sketch basis, simply define #MAX_CALLBACKS_PER_BUTTON before your #includes.