FAQ

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