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  2. Technische Fakultät
  3. Department Informatik
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            libspicboard-doc

            Files | Typedefs | Enumerations | Functions
            Button

            Enables event-driven and polling access to the buttons of the SPiCboard. More...

            Files

            file  button.h
             

            Typedefs

            typedef void(* BUTTONCALLBACK) (BUTTON, BUTTONEVENT)
             Type for button event callback functions. More...
             

            Enumerations

            enum  BUTTON { BUTTON0 , BUTTON1 }
             Identifiers for all available buttons. More...
             
            enum  BUTTONSTATE { UNKNOWN , PRESSED , RELEASED }
             States for buttons. More...
             
            enum  BUTTONEVENT { ONPRESS , ONRELEASE }
             Events for buttons. More...
             

            Functions

            int8_t sb_button_registerCallback (BUTTON btn, BUTTONEVENT eve, BUTTONCALLBACK callback)
             Register a callback function for a button event. More...
             
            int8_t sb_button_unregisterCallback (BUTTON btn, BUTTONEVENT eve, BUTTONCALLBACK callback)
             Unregister a callback function for a button event. More...
             
            BUTTONSTATE sb_button_getState (BUTTON btn)
             Query the current state of a button. More...
             

            Detailed Description

            Enables event-driven and polling access to the buttons of the SPiCboard.

            The SPiCboard is equipped with two buttons. Button 0 is debounced in hardware, whereas Button 1 needs to be debounced in software by the button module. Debouncing is transparent to the application, that can use both buttons through the provided interface without the need to care about debouncing.

            The debouncing code makes use of a timer. When no callbacks are registered for Button 1, the debouncing code is disabled and all alarms registered at the timer should be canceled.

            The button module uses dynamic memory management to maintain the callback queues.

            Typedef Documentation

            typedef void(* BUTTONCALLBACK) (BUTTON, BUTTONEVENT)

            Type for button event callback functions.

            A button callback function is called on the interrupt level whenever an event at a button occurs that the function was registered for. The callback function is passed the button id and the type of event that occurred. This way, the same callback function can be registered for different buttons and events.

            Enumeration Type Documentation

            enum BUTTON

            Identifiers for all available buttons.

            Enumerator
            BUTTON0 

            Button 0

            BUTTON1 

            Button 1

            enum BUTTONEVENT

            Events for buttons.

            Down (on press) and up (on release) events for buttons.

            Enumerator
            ONPRESS 

            Button is pressed

            ONRELEASE 

            Button is released

            enum BUTTONSTATE

            States for buttons.

            Pressed and released states for buttons.

            Enumerator
            UNKNOWN 

            Buttonstate is unknown (invalid button?)

            PRESSED 

            Button is pressed

            RELEASED 

            Button is released

            Function Documentation

            BUTTONSTATE sb_button_getState ( BUTTON  btn)

            Query the current state of a button.

            Parameters
            btnid of the button
            Returns
            the buttons current state (pressed or released - or unknown if invalid button) as a BUTTONSTATE
            int8_t sb_button_registerCallback ( BUTTON  btn,
            BUTTONEVENT  eve,
            BUTTONCALLBACK  callback 
            )

            Register a callback function for a button event.

            Interrupts must be enabled to receive the callbacks.

            Parameters
            btnthe id of the button
            evethe type of event that the callback function should be invoked for.
            callbackpointer to the callback function. This function is called from the interrupt handler.
            Return values
            0success,
            !0error
            See also
            sb_button_unregisterCallback
            int8_t sb_button_unregisterCallback ( BUTTON  btn,
            BUTTONEVENT  eve,
            BUTTONCALLBACK  callback 
            )

            Unregister a callback function for a button event.

            Parameters
            btnthe id of the button
            evethe type of event that the callback function should be invoked for.
            callbackpointer to the callback function
            Returns
            0 on success, negative value on error
            Return values
            0success
            -1the callback function was not registered with the given button/event combination
            See also
            sb_button_registerCallback
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